Management of Ventricular Arrhythmias and Sudden Cardiac Arrest: Part 2

167 question(s) with answers and explanations.

Question 1

A 65-year-old woman is admitted to the cardiac unit for symptomatic palpitations and lightheadedness. On continuous electrocardiogram (ECG) telemetry, she is noted to have a run of 15 consecutive broad QRS complex beats at a rate of 140 beats per minute without preceding P-waves. The QRS complexes continually change in morphology from beat to beat. The episode terminates spontaneously after 12 seconds without the need for medical intervention. Based on these findings, how is this specific arrhythmia episode best classified?

• ✓ Non-sustained polymorphic ventricular tachycardia
• ○ Sustained polymorphic ventricular tachycardia
• ○ Bidirectional ventricular tachycardia
• ○ Multifocal premature ventricular complexes

Explanation. A run of consecutive ventricular beats persisting for between 3 beats and 30 seconds at a rate greater than 100 beats per minute is defined as non-sustained ventricular tachycardia. The continual changing of the QRS morphology from beat to beat further characterizes the arrhythmia as polymorphic.

Question 2

A 62-year-old man with a history of an ischemic cardiomyopathy and an implantable cardioverter-defibrillator (ICD) presents to the emergency department. Interrogation of the device reveals that he has had four distinct episodes of sustained ventricular tachycardia over the last 12 hours. Each episode was separated by at least 30 minutes of normal sinus rhythm and was successfully terminated by an appropriate shock from the ICD. Which of the following terms best describes this clinical scenario?

• ✓ Electrical storm
• ○ Incessant ventricular tachycardia
• ○ Torsades de pointes ventricular tachycardia
• ○ Ventricular fibrillation

Explanation. Electrical storm is defined as a ventricular arrhythmia that occurs 3 or more times within a 24-hour period, with each episode separated by at least 5 minutes, and requiring termination by a therapeutic intervention (such as an ICD shock).

Question 3

A 22-year-old previously healthy female unexpectedly collapses and dies in her sleep. A thorough post-mortem evaluation is conducted to determine the cause. The detailed pathological assessment reveals no structural cardiac abnormalities or other anatomic anomalies, and a comprehensive toxicological screen is entirely negative. What is the most appropriate diagnostic term for this unexplained event in an individual older than 1 year?

• ✓ Sudden arrhythmic death syndrome (SADS)
• ○ Sudden infant death syndrome (SIDS)
• ○ Arrhythmic syncope
• ○ Idiopathic ventricular fibrillation (IVF)

Explanation. Sudden arrhythmic death syndrome (SADS) is defined as an unexplained sudden death occurring in an individual older than 1 year of age who has a completely negative pathological and toxicological assessment.

Question 4

A 48-year-old male with a non-ischemic dilated cardiomyopathy and an implantable cardioverter-defibrillator experiences multiple appropriate shocks for recurrent sustained ventricular tachycardia (VT) refractory to amiodarone. He is referred for catheter ablation. Given the high procedural complexity anticipated with a non-ischemic etiology, he is directed to a specialized center. Which of the following represents the necessary operator experience and institutional capabilities required for this specialized center?

• ✓ At least one operator experienced in percutaneous epicardial access, regular performance of VT ablation in structural heart disease, and the capacity for acute mechanical circulatory assist device placement along with cardiothoracic surgical back-up.
• ○ At least one operator experienced in transseptal puncture, regular performance of supraventricular tachycardia ablation, and the capacity for non-invasive stereotactic radioablation with genetic counseling availability.
• ○ At least two operators experienced in endocardial ablation, regular performance of VT ablation in structurally normal hearts, and an on-site advanced heart failure transplant program.
• ○ At least one operator with interventional cardiology expertise exclusively for coronary revascularization, regular performance of ischemic VT ablation, and continuous remote monitoring capabilities.

Explanation. A specialized center for complex catheter ablation of ventricular arrhythmias requires at least one operator with experience in advanced interventions that may be needed for a successful procedure, such as percutaneous epicardial access, which is particularly relevant for non-ischemic etiologies. Furthermore, the institution must regularly perform VT ablation in structural heart disease and possess comprehensive resources to manage severe comorbidities and potential complications, including interventional cardiology expertise, acute placement of mechanical circulatory assist devices, and cardiothoracic surgical back-up.

Question 5

A 42-year-old previously healthy man collapses while jogging and dies before the arrival of emergency medical services. He had no known medical history and had not seen a physician in years. His family is devastated and asks the attending physician about the likelihood of this being a sudden cardiac death (SCD) and whether an autopsy is necessary. Based on epidemiological data and recommended protocols for suspected SCD, which of the following is the most accurate statement regarding this presentation?

• ✓ Sudden cardiac death accounts for approximately 50% of all cardiovascular deaths, and up to 50% of the time, it is the first manifestation of cardiac disease; an autopsy is required to reliably exclude non-cardiac causes.
• ○ Sudden cardiac death accounts for approximately 25% of all cardiovascular deaths, and it is rarely the first manifestation of cardiac disease; an autopsy is only required if illicit drug use is suspected.
• ○ Since he was previously healthy, this is highly unlikely to be a cardiac event, as sudden cardiac death is the first manifestation of cardiac disease in less than 5% of cases.
• ○ An autopsy is not necessary because the clinical presentation of collapsing while jogging is definitively diagnostic of an arrhythmogenic cardiac event.

Explanation. Sudden cardiac death accounts for approximately 50% of all cardiovascular deaths, with up to 50% being the first manifestation of cardiac disease. In cases suspicious of SCD, an autopsy is required to reliably exclude non-cardiac causes of sudden death.

Question 6

A 75-year-old male with a history of hypertension, hyperlipidemia, and coronary artery disease (CAD) presents to the cardiology clinic for a routine follow-up. He expresses concern about his risk of sudden cardiac death (SCD) after a friend of the same age recently passed away from an out-of-hospital cardiac arrest. During a teaching discussion regarding the epidemiological characteristics of SCD in patients like this one, which of the following statements is accurate?

• ○ The overall incidence of SCD is increasing proportionally with the rising prevalence of CAD.
• ○ The incidence of SCD in this patient's age group is approximately 50 per 100,000 person-years.
• ✓ Although the absolute incidence of SCD is declining, it may represent an increasing proportion of overall cardiovascular deaths.
• ○ Males and females share an equal baseline risk of SCD once adjusted for traditional CAD risk factors.

Explanation. While there has been a significant decline in overall mortality due to coronary artery disease, resulting in a declining absolute incidence of sudden cardiac death (SCD), the risk of SCD as a proportion of overall cardiovascular deaths has increased.

Question 7

A 36-year-old male suddenly collapses and suffers sudden cardiac arrest while playing a recreational game of basketball. Resuscitative efforts are unsuccessful. Which of the following is the most likely underlying cause of sudden cardiac death in a patient in this decade of life?

• ✓ Coronary artery disease, particularly acute coronary syndrome
• ○ Arrhythmogenic right ventricular cardiomyopathy
• ○ Anomalous origin of a coronary artery
• ○ Primary electrical disease such as Long QT syndrome

Explanation. Half of sudden cardiac death cases during the fourth decade of life (ages 30-39) are related to coronary artery disease, especially acute coronary syndrome. Furthermore, the majority of sports-related sudden cardiac death occurs in a recreational setting among middle-aged males, with coronary artery disease being the most common underlying cause.

Question 8

A 45-year-old male with no known history of cardiovascular disease presents to his physician for a wellness exam. He expresses significant anxiety about sudden cardiac death (SCD) after a co-worker recently died unexpectedly. He has no exertional symptoms, palpitations, or family history of premature cardiovascular disease. He inquires about the best strategy to assess and mitigate his risk for SCD. Which of the following represents the most effective approach for preventing SCD in this patient?

• ✓ Calculation of his risk of developing coronary artery disease (CAD) using standard risk score charts.
• ○ Implementation of a mass population screening protocol utilizing resting 12-lead electrocardiograms (ECGs).
• ○ Empiric genetic testing to identify alleles predisposing to sudden death during acute ischemia.
• ○ Routine performance of an exercise treadmill stress test to identify silent myocardial ischemia.

Explanation. In individuals in the general population without known heart disease, the most effective approach for preventing sudden cardiac death resides in the quantification of the individual risk of developing coronary artery disease based on established risk score charts.

Question 9

An 82-year-old man with chronic coronary artery disease (CAD), severely reduced left ventricular ejection fraction (LVEF), and New York Heart Association (NYHA) class III heart failure is evaluated for an implantable cardioverter-defibrillator (ICD) for the primary prevention of sudden cardiac death (SCD). He also has advanced chronic obstructive pulmonary disease and metastatic prostate cancer, both of which confer a high near-term mortality risk. Which of the following concepts best describes why the placement of an ICD may be of limited benefit for this specific patient?

• ✓ Non-SCD deaths act as competing events that prevent the observation of SCD.
• ○ Heart rate variability and late potentials confound the estimation of SCD risk.
• ○ Risk stratification calculators for inherited cardiomyopathies lose predictive value in the elderly.
• ○ Baroreflex sensitivity is significantly diminished in the presence of metastatic disease.

Explanation. Non-sudden cardiac death (SCD) deaths serve as competing risks; their occurrence prevents the observation of SCD, which makes interventions specifically aimed at preventing SCD, such as an implantable cardioverter-defibrillator (ICD), of limited benefit in patients with a high risk of death from other causes.

Question 10

A clinical researcher is reviewing a newly published risk calculator for sudden cardiac death (SCD) to determine its suitability for identifying patients who may benefit from an implantable cardioverter-defibrillator (ICD). Which of the following methodological characteristics represents a typical shortcoming in the development and validation of such risk prediction models?

• ✓ The use of composite outcomes consisting of events with different clinical importance.
• ○ The evaluation of the model in contemporary patient cohorts instead of historic samples.
• ○ The inclusion of calibration measures, such as the calibration slope, to quantify absolute risk.
• ○ The application of varying 5-year risk cut-offs for ICD indication based on specific outcomes and competing risks.

Explanation. A recognized shortcoming in the development and validation of sudden cardiac death risk calculators is the use of composite outcomes that combine events of varying clinical importance, which can obscure the true prediction capability for the most critical events.

Question 11

A 55-year-old man suddenly collapses in a busy shopping centre. A bystander immediately begins cardiopulmonary resuscitation (CPR) while another person fetches an automated external defibrillator (AED) located nearby. The patient is successfully resuscitated before emergency medical services arrive. Which of the following community-level interventions is most critical to replicating this positive outcome and improving overall survival and neurological recovery in out-of-hospital cardiac arrest (OHCA) victims?

• ✓ Implementing networks that dispatch basic life support-trained volunteers via mobile apps and increasing public access to AEDs.
• ○ Restricting AED access to trained medical personnel within public venues to prevent device misuse.
• ○ Initiating community basic life support training exclusively in adulthood to ensure optimal skill retention.
• ○ Focusing resources primarily on reducing the response time of advanced life support emergency medical services rather than layperson interventions.

Explanation. Bystander cardiopulmonary resuscitation (CPR) and the use of public automated external defibrillators (AEDs) demonstrate marked improvements in neurological and functional outcomes and survival for out-of-hospital cardiac arrest. The dispatch of basic life support-trained volunteers via mobile app networks increases bystander-initiated CPR rates, significantly reducing the resuscitation-free interval and improving patient outcomes.

Question 12

A 28-year-old man is evaluated in the cardiology clinic after an episode of syncope that occurred without any vagal prodrome. His family history is notable for an uncle who died suddenly at age 35. On physical examination, his cardiovascular exam is unremarkable, but inspection of his skin reveals marked thickening and hyperkeratotic plaques on his palms and soles. Based on these findings, which of the following underlying conditions is most strongly suspected?

• ✓ Arrhythmogenic right ventricular cardiomyopathy
• ○ Fabry's disease
• ○ Cardiac sarcoidosis
• ○ Long QT syndrome

Explanation. Palmoplantar keratosis is a specific dermatological feature that serves as a clinical 'red flag' pointing toward an underlying diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) in patients presenting with features of arrhythmic syncope and a family history of premature sudden cardiac death.

Question 13

A 50-year-old male with a history of hypertension and frequent palpitations undergoes a two-dimensional echocardiogram. His left ventricular ejection fraction (LVEF) is 62%, and there is no overt valvular disease. The cardiologist wishes to assess for subtle left ventricular dysfunction and mechanical dispersion, which reflects inhomogeneous contraction and an increased risk of ventricular arrhythmias (VA). Which of the following imaging modalities or parameters is most appropriate for this specific evaluation?

• ✓ Global longitudinal strain imaging
• ○ Continuous-wave Doppler imaging
• ○ Three-dimensional volumetric echocardiography
• ○ Contrast-enhanced resting echocardiography

Explanation. Global longitudinal strain is a robust measure of left ventricular function that can detect subtle changes while the left ventricular ejection fraction is still preserved, and strain imaging can directly assess mechanical dispersion reflecting inhomogeneous contraction that is associated with an increased risk of ventricular arrhythmias.

Question 14

A 35-year-old male with newly diagnosed hypertrophic cardiomyopathy (HCM) undergoes cardiac magnetic resonance (CMR) imaging to further evaluate his condition. The CMR reveals prominent asymmetric septal hypertrophy along with the presence of myocardial fibrosis identified by late gadolinium enhancement (LGE). What is the primary clinical significance of identifying LGE in this specific patient?

• ○ It identifies the specific etiology of the left ventricular hypertrophy as amyloidosis.
• ✓ It contributes to the risk stratification for future ventricular arrhythmias.
• ○ It serves as the diagnostic criterion for left ventricular non-compaction.
• ○ It rules out the presence of obstructive coronary artery disease.

Explanation. The identification of myocardial fibrosis using late gadolinium enhancement (LGE) during cardiac magnetic resonance imaging is a key parameter that contributes directly to the risk stratification for ventricular arrhythmias in patients with hypertrophic cardiomyopathy.

Question 15

A 12-year-old girl is referred to the cardiology clinic after experiencing a syncopal episode while swimming. Her baseline electrocardiogram (ECG) shows a borderline prolonged QTc interval of 465 ms. The cardiologist suspects congenital long QT syndrome (LQTS). The patient has no physical limitations and is fully capable of exercising on a treadmill. When considering provocative testing to aid in the diagnosis, which of the following approaches is most appropriate?

• ○ Perform an epinephrine challenge as it is the most specific test for LQTS.
• ✓ Utilize exercise testing and avoid an epinephrine challenge due to its high false-positive rate.
• ○ Administer sodium channel blockers to unmask the underlying repolarization abnormality.
• ○ Proceed with an electrophysiological study using programmed electrical stimulation from two right ventricular sites.

Explanation. The epinephrine test is not recommended for the diagnosis of long QT syndrome (LQTS) due to its high false-positive rate and the well-established utility of exercise testing.

Question 16

A 58-year-old male with a history of a prior myocardial infarction 5 years ago presents to the emergency department after an episode of unexplained syncope. Echocardiography reveals a mildly reduced left ventricular ejection fraction (LVEF) of 45% with an area of inferior wall akinesis. He has no documented arrhythmias on initial telemetry or a 48-hour Holter monitor. His electrocardiogram (ECG) shows normal sinus rhythm with Q waves in the inferior leads. Which of the following statements regarding the use of programmed electrical stimulation (PES) in this patient is most accurate?

• ✓ Induction of sustained monomorphic ventricular tachycardia (SMVT) during PES can help identify the underlying cause of syncope and predict subsequent events.
• ○ PES is primarily indicated to evaluate for concurrent primary electrical diseases, as it has high prognostic value in these conditions.
• ○ PES is not necessary because the patient already has a primary prevention indication for an implantable cardioverter-defibrillator (ICD) based on his LVEF.
• ○ Induction of polymorphic ventricular tachycardia (PVT) or ventricular fibrillation (VF) during PES is a highly specific finding that predicts sudden cardiac death in structural heart disease.

Explanation. In patients with structural heart disease and mildly reduced or preserved left ventricular ejection fraction who present with unexplained syncope, the induction of sustained monomorphic ventricular tachycardia with programmed electrical stimulation is a helpful tool to identify the underlying arrhythmic cause of the syncope and to predict subsequent clinical events.

Question 17

A 34-year-old man presents to the cardiology clinic after his brother suffered a sudden cardiac arrest and was diagnosed with Brugada syndrome post-mortem. The patient wishes to undergo genetic testing. A next-generation sequencing panel is ordered for diagnostic evaluation. The laboratory provides a sequencing report that details several types of genetic alterations. Which of the following represents the most common type of genetic alteration affecting the coding frame expected to be found in such diagnostic evaluations?

• ○ Large insertions and deletions significantly altering the non-coding regions.
• ○ Common single nucleotide polymorphisms currently utilized as a definitive polygenic risk score for routine diagnosis.
• ✓ Single nucleotide variants causing simple amino acid substitutions, premature terminations, or splicing abnormalities.
• ○ Variants in historically identified candidate genes with questionable diagnostic utility that are routinely recommended for broad panels.

Explanation. In diagnostic cardiac genetic testing using next-generation sequencing, the most common findings affecting the coding frame of a gene are single nucleotide variants that cause simple amino acid substitutions (missense mutations), premature terminations, or splicing abnormalities.

Question 18

A 30-year-old male is clinically diagnosed with arrhythmogenic right ventricular cardiomyopathy. Genetic testing identifies a variant in the desmoplakin gene. The laboratory report categorizes this finding as a Class IV variant. He has a healthy 5-year-old daughter and is planning to have another child with his wife. He asks his cardiologist how this genetic finding should be utilized for his family's ongoing care and family planning. Which of the following is the most appropriate approach?

• ✓ The variant can be used immediately for the genetic testing of his daughter, its classification should undergo periodic reassessment, and information regarding pre-implantation genetic testing should be provided.
• ○ Genetic testing of his daughter must be deferred until the variant is definitively reclassified as a Class V mutation, though information about pre-implantation genetic testing should be provided immediately.
• ○ The variant establishes a definitive diagnosis and can be used for family screening immediately, but periodic reassessment of its pathogenicity is not indicated once cascade testing begins.
• ○ The variant is currently considered to be of uncertain significance, meaning cascade genetic screening of his daughter is contraindicated until periodic reassessment elevates its classification.

Explanation. A Class IV variant is defined as 'likely pathogenic' and can be utilized immediately for the initial diagnosis of relatives through cascade screening. Because the variant is Class IV rather than definitively pathogenic, periodic reassessment of its classification is indicated to integrate any newly available clinical, population, or functional data. Additionally, patients of child-bearing age with a monogenic heart disease should be provided with information regarding pre-implantation genetic testing, which allows for the biopsy of in vitro fertilized embryos and the subsequent transfer of genetically normal embryos.

Question 19

A 28-year-old male with a history of unexplained recurrent syncope during physical exertion is evaluated. His resting electrocardiogram (ECG) reveals a markedly prolonged QTc interval of 510 ms without any identifiable secondary causes such as QT-prolonging medications or electrolyte abnormalities. He undergoes genetic testing for primary electrical diseases, but the comprehensive panel returns negative for any known pathogenic variants. How should this genetic test result be interpreted in the context of this patient's diagnosis?

• ○ It excludes the diagnosis of a primary inherited electrical disease, requiring investigation solely into acquired etiologies.
• ○ It confirms the patient's presentation is an environmental phenocopy rather than a genetic syndrome.
• ✓ It does not exclude the diagnosis of a primary electrical disease, and the diagnosis remains supported by his clinical phenotype.
• ○ It requires immediate reflexive testing for structural heart disease mutations before a diagnosis can be made.

Explanation. In the evaluation of primary electrical diseases, a negative genetic test result does not exclude a diagnosis and should not be used to rule out the disease. The clinical phenotype, such as a markedly prolonged QTc interval with exertional syncope, remains central to establishing the diagnosis and guiding ongoing management despite the absence of an identifiable pathogenic genetic variant.

Question 20

A 50-year-old male with occasional palpitations undergoes a 3-lead Holter monitor, which shows several short runs of non-sustained ventricular tachycardia (NSVT). A resting 12-lead electrocardiogram (ECG) and transthoracic echocardiogram are both unremarkable. He mentions that his palpitations occur primarily when he plays tennis. An exercise stress test is performed to capture a full 12-lead ECG of the NSVT. During the test, there is an increasing frequency of multifocal ventricular arrhythmias with exercise, which do not appear to have an idiopathic origin. What is the most appropriate recommendation regarding his physical activity at this time?

• ✓ Advise the patient to refrain from physical exercise until a diagnosis is established and appropriate treatment is initiated.
• ○ Recommend that he only engage in low-intensity physical exercise while continuing the diagnostic evaluation.
• ○ Reassure him that exercise-induced arrhythmias without echocardiographic abnormalities are benign and encourage regular exercise.
• ○ Allow him to continue playing tennis provided he takes a dose of an oral beta-blocker prior to exertion.

Explanation. Increasing ventricular arrhythmias with exercise that are not suggestive of an idiopathic origin should raise the suspicion of underlying structural heart disease. This finding necessitates advising the patient to refrain from physical exercise until a definitive diagnosis is made and appropriate treatment is initiated.

Question 21

A 42-year-old male is evaluated after an incidental finding of non-sustained ventricular tachycardia (NSVT) on a 24-hour Holter monitor placed prior to the initiation of oncological treatment. Initial echocardiography reveals mild left ventricular dilation and an ejection fraction of 48%, raising suspicion for an underlying cardiomyopathy. The patient is referred for cardiovascular magnetic resonance (CMR) imaging. In this clinical context, what is a key pathophysiological feature that the CMR is specifically used to identify?

• ✓ Areas of fibrosis acting as substrates for the NSVT
• ○ The specific morphology of the NSVT to confirm an idiopathic origin
• ○ The cycle length of short-coupled premature ventricular complexes
• ○ Active triggers of typical monomorphic ventricular tachycardia

Explanation. Cardiovascular magnetic resonance (CMR) imaging is utilized when cardiomyopathies or inflammatory diseases are suspected on initial evaluation because it has the unique tissue-characterization capability to identify areas of myocardial fibrosis, which serve as the arrhythmogenic substrates for non-sustained ventricular tachycardia.

Question 22

A 68-year-old male with a history of a previous anterior myocardial infarction presents to the emergency department with palpitations and presyncope. A 12-lead electrocardiogram (ECG) reveals a wide QRS complex tachycardia at a rate of 160 beats per minute with uniform beat-to-beat morphology, establishing a diagnosis of a first episode of sustained monomorphic ventricular tachycardia (SMVT). Following successful cardioversion, further evaluation is initiated. What is the most likely underlying electrophysiological mechanism responsible for this patient's presentation?

• ✓ Scar-related re-entry associated with structural heart disease (SHD)
• ○ Re-entry involving a diseased His-Purkinje conduction system
• ○ Enhanced automaticity originating from a localized focal source
• ○ Triggered activity induced by a short-coupled premature ventricular contraction

Explanation. The majority of patients presenting with a first episode of sustained monomorphic ventricular tachycardia (SMVT) have underlying structural heart disease (SHD), such as a prior myocardial infarction. In patients with SHD, the arrhythmia is mainly driven by scar-related re-entry mechanisms within the diseased myocardium.

Question 23

A 35-year-old male presents with palpitations and lightheadedness. A 12-lead electrocardiogram (ECG) during the episode documents sustained ventricular tachycardia (VT) with an atypical morphology that does not fit a standard right ventricular outflow tract (RVOT) or fascicular pattern. His baseline resting ECG and a comprehensive transthoracic echocardiogram are entirely normal. He has no known family history of cardiomyopathy. What is the most appropriate next diagnostic step to evaluate this patient's condition?

• ✓ Perform cardiac magnetic resonance (CMR) imaging.
• ○ Reassure the patient that the VT is idiopathic based on the normal echocardiogram.
• ○ Schedule an endomyocardial biopsy to evaluate for subtle cardiomyopathies.
• ○ Perform a coronary angiogram to assess for an ischemic etiology.

Explanation. Atypical electrocardiogram morphologies and uncommon clinical presentations during ventricular tachycardia raise the suspicion for underlying structural heart disease, even in cases where the baseline resting ECG and transthoracic echocardiogram appear normal. In such scenarios, further evaluation with cardiac magnetic resonance imaging is indicated to identify subtle structural abnormalities that are not visible on standard echocardiography.

Question 24

A 28-year-old previously healthy woman presents to the emergency department complaining of sudden onset palpitations and lightheadedness. Her vitals are stable, but her heart rate is 175 beats per minute. A 12-lead electrocardiogram (ECG) demonstrates a sustained monomorphic wide-complex tachycardia. The QRS complex exhibits a left bundle branch block (LBBB)-like morphology, an inferior axis, and a precordial transition at lead V4. What is the most likely etiology of this patient's arrhythmia?

• ✓ Right ventricular outflow tract (RVOT) ventricular tachycardia
• ○ Left ventricular (LV) fascicular ventricular tachycardia
• ○ Arrhythmogenic right ventricular cardiomyopathy (ARVC) with focal scar
• ○ Cardiac sarcoidosis with focal right ventricular involvement

Explanation. The electrocardiographic features of a left bundle branch block (LBBB)-like morphology combined with an inferior axis and a precordial transition at lead V4 are the characteristic diagnostic findings of right ventricular outflow tract (RVOT) ventricular tachycardia.

Question 25

A 65-year-old man has an out-of-hospital cardiac arrest (ventricular fibrillation) and is successfully resuscitated by paramedics. Upon arrival at the emergency department, he is intubated and comatose. A 12-lead electrocardiogram (ECG) reveals sinus tachycardia without ST-segment elevation. Over the next 30 minutes, he develops recurrent episodes of polymorphic ventricular tachycardia requiring repeated defibrillation and amiodarone administration. His blood pressure drops significantly during these episodes, and there is a high clinical suspicion for ongoing ischemia. Based on the patient's presentation, what is the most appropriate management regarding coronary angiography (CAG)?

• ✓ Immediate coronary angiography is indicated due to the presence of electrical instability suspicious for ongoing ischemia.
• ○ Early coronary angiography is not beneficial in patients without ST-segment elevation and should be deferred until he regains consciousness.
• ○ Coronary angiography should be performed only after a brain and chest computed tomography (CT) scan definitively exclude non-cardiac causes of arrest.
• ○ Coronary angiography should be deferred until toxicological analysis and DNA testing from retained blood samples are completed.

Explanation. Although early coronary angiography generally has not shown significant benefit in patients with cardiac arrest without ST-segment elevation, it is indicated in cases where there is electrical instability after the cardiac arrest that raises suspicion for ongoing ischemia.

Question 26

A 22-year-old male experiences an aborted sudden cardiac arrest. Serial resting 12-lead electrocardiograms (ECGs), including high precordial leads, are normal. Echocardiography, coronary angiography, and cardiac magnetic resonance (CMR) imaging show no structural abnormalities or ischemic heart disease. Which of the following provocative tests is a recognized maneuver to uncover a primary electrical disease in such a patient?

• ✓ Sodium channel blocker challenge
• ○ Dobutamine challenge
• ○ Phenylephrine challenge
• ○ Cold pressor test

Explanation. In cases where structural and ischemic causes of cardiac arrest have been excluded, primary electrical diseases may be uncovered by specific provocative maneuvers. Recognized maneuvers include the sodium channel blocker challenge, lying to standing ECGs, adenosine challenge, epinephrine challenge, ergonovine or acetylcholine administration, mental stress, and exercise testing.

Question 27

A 42-year-old previously healthy man collapses while jogging and cannot be resuscitated. He is pronounced dead at the scene. His 38-year-old sister presents to the cardiology clinic for counseling regarding her own cardiovascular risk and the utility of post-mortem evaluation of her brother. When counseling this patient regarding the likelihood of identifying a potential genetic cardiac disease as the cause of her brother's sudden cardiac death (SCD), which of the following represents the anticipated diagnostic yield in victims in this age group?

• ○ Less than 10%
• ○ 10% to 20%
• ✓ 25% to 49%
• ○ 65% to 80%

Explanation. Potential genetic cardiac disease can be identified in 25% to 49% of cases of sudden cardiac death in the young, which is defined as individuals under 50 years of age.

Question 28

A 28-year-old male with no prior medical history dies suddenly during his sleep. An autopsy reveals no gross or microscopic structural heart abnormalities, and a comprehensive toxicology screen is negative. The cause of death is classified as sudden arrhythmic death syndrome (SADS). Which of the following statements is most accurate regarding the subsequent evaluation of this case and his family?

• ✓ Clinical evaluation of his first-degree relatives may identify an underlying genetic heart disease in approximately 18% to 53% of cases.
• ○ Post-mortem genetic analysis is generally deferred as the diagnostic yield in autopsy-negative sudden death cases is negligible.
• ○ Re-evaluation of the heart by an expert cardiac pathologist is unnecessary as initial negative autopsies are rarely altered.
• ○ Routine toxicology screens reveal drug overdose or polypharmacy as the cause of sudden death in less than 5% of young individuals.

Explanation. In cases of sudden arrhythmic death syndrome (SADS) where an autopsy and toxicology screen are negative, clinical evaluation of first-degree relatives is critical to uncover primary electrical diseases or underlying genetic heart conditions. Evaluating the families of SADS decedents identifies an underlying genetic heart disease that is presumed to be the cause of death in approximately 18% to 53% of cases.

Question 29

A 25-year-old female is evaluated in the inherited arrhythmia clinic following the sudden death of her 23-year-old brother. The brother's autopsy was ambiguous, but his prior medical records indicated a history of recurrent syncope triggered by intense emotional stress and startling noises, raising high clinical suspicion for catecholaminergic polymorphic ventricular tachycardia (CPVT). The patient is scheduled for clinical screening but is currently unable to undergo treadmill or bicycle exercise testing due to a recent complex knee fracture. Which of the following alternative provocative testing strategies is most appropriate to evaluate for the suspected condition in this patient?

• ○ Sodium channel blocker drug challenge
• ✓ Epinephrine challenge
• ○ Signal-averaged electrocardiogram (ECG)
• ○ Adenosine challenge

Explanation. Epinephrine challenge may be of utility to unmask arrhythmias in patients suspected of having catecholaminergic polymorphic ventricular tachycardia (CPVT) who are physically unable to perform standard exercise stress testing.

Question 30

A 35-year-old woman is admitted to the intensive care unit after surviving a sudden cardiac arrest (SCA) initially presenting as ventricular fibrillation. Her family reports that she had recently started an extreme fasting diet for rapid weight loss and had been experiencing a low-grade fever over the past 48 hours. In assessing and managing reversible triggers for her ventricular arrhythmia (VA), which of the following electrolyte derangements is most recognized as a direct trigger for this specific dysrhythmia?

• ✓ Hypokalemia
• ○ A rapid rise in extracellular potassium
• ○ Hypermagnesemia
• ○ Hypercalcemia

Explanation. Electrolyte imbalances such as hypokalemia are established reversible causes that can directly trigger ventricular arrhythmias. Additional physiological stressors including acute starvation, restrictive dieting, and fever are also recognized factors that contribute to the occurrence of ventricular arrhythmias and require acute correction.

Question 31

A 68-year-old female is brought to the emergency department after a syncopal episode. She was recently started on sotalol for atrial fibrillation and takes a thiazide diuretic for hypertension. Continuous telemetric monitoring reveals an episode of polymorphic ventricular tachycardia with QRS complexes twisting around the isoelectric line. Offending medications are immediately withdrawn, and she is treated with an initial bolus of intravenous magnesium sulfate. Despite these measures and having normal serum potassium and magnesium levels, she continues to experience recurrent, refractory episodes of this arrhythmia. Which of the following is the most appropriate next step to suppress the recurrent arrhythmia?

• ○ Administer intravenous amiodarone to stabilize the myocardial membrane.
• ✓ Initiate an infusion of isoproterenol or perform temporary transvenous pacing.
• ○ Administer intravenous metoprolol to reduce sympathetic drive.
• ○ Refer the patient for immediate placement of an implantable cardioverter-defibrillator (ICD).

Explanation. In refractory cases of recurrent Torsades de pointes (TdP) occurring in the setting of acquired long QT syndrome, the arrhythmia can be effectively suppressed by increasing the underlying heart rate. This acceleration of the heart rate shortens the repolarization time and the QT interval, which can be achieved pharmacologically with chronotropic agents such as isoproterenol, or electrically through temporary transvenous pacing.

Question 32

A 30-year-old healthy female presents for a cardiac evaluation. Her 35-year-old brother recently suffered an unexplained sudden cardiac death (SCD) during sleep, and complete autopsy results revealed no toxicological or structural cause of death. The patient is currently asymptomatic, and her baseline electrocardiogram (ECG) and physical examination are unremarkable. Which of the following interventions is most strongly indicated for this patient?

• ✓ Comprehensive familial evaluation, genetic counseling, and cascade testing
• ○ Ambulatory cardiac rhythm monitoring and cardiac magnetic resonance (CMR) imaging
• ○ Provocation testing with an intravenous sodium channel blocker
• ○ Routine clinical follow-up in 5 years given the normal baseline electrocardiogram

Explanation. For first-degree relatives of an unexplained sudden death decedent of young age (under 50 years) or with circumstances suggestive of heritable heart disease, familial evaluation, genetic counseling, and cascade testing are highly indicated interventions to identify potential obligate carriers or relatives at risk for arrhythmogenic conditions.

Question 33

A 32-year-old man presents to the emergency department complaining of sudden-onset severe palpitations and mild lightheadedness. He is awake and alert, with a blood pressure of 115/75 mmHg and a respiratory rate of 18 breaths per minute. A 12-lead electrocardiogram (ECG) is obtained, revealing a wide-complex tachycardia with an average rate of 210 beats per minute. The rhythm is notably irregular, and the QRS complexes vary in morphology and width from beat to beat, demonstrating a "fast, broad, irregular" pattern. Which of the following pharmacological interventions should be strictly avoided in the acute management of this patient?

• ○ Intravenous procainamide
• ✓ Intravenous adenosine
• ○ Intravenous ibutilide
• ○ Intravenous flecainide

Explanation. The patient's electrocardiogram showing a "fast, broad, irregular" pattern is characteristic of pre-excited atrial fibrillation, which can easily mimic ventricular tachycardia. In this condition, atrial impulses conduct rapidly down an accessory pathway, bypassing the atrioventricular (AV) node. Administering intravenous drugs that slow AV nodal conduction, such as adenosine, beta-blockers, or amiodarone, is strictly contraindicated because these agents can selectively enhance anterograde conduction over the accessory pathway, potentially leading to a dangerously rapid ventricular response and immediate degeneration into ventricular fibrillation.

Question 34

A 55-year-old woman presents to the emergency department with a 1-hour history of rapid heart palpitations. She is awake, alert, and her blood pressure is 130/80 mmHg. A 12-lead electrocardiogram (ECG) demonstrates a wide complex tachycardia consistent with ventricular tachycardia (VT) of unknown aetiology. She has no significant past medical history, and a rapid bedside echocardiogram is unremarkable. The physician opts for pharmacological termination. Based on clinical trial data comparing intravenous amiodarone and procainamide in this setting, which of the following describes the expected comparative outcome if intravenous procainamide is administered?

• ✓ A higher proportion of tachycardia termination and fewer major cardiac adverse events compared to amiodarone.
• ○ A similar rate of tachycardia termination but a significantly higher rate of major cardiac adverse events compared to amiodarone.
• ○ A lower proportion of tachycardia termination but fewer major cardiac adverse events compared to amiodarone.
• ○ A higher proportion of tachycardia termination but a significantly higher risk of profound hypotension compared to amiodarone.

Explanation. Intravenous procainamide is an effective option for the pharmacological termination of a haemodynamically tolerated ventricular tachycardia of unknown aetiology. Clinical trial evidence demonstrates that procainamide therapy is associated with a higher proportion of tachycardia termination and fewer major cardiac adverse events when compared directly to amiodarone.

Question 35

A 28-year-old previously healthy male presents to the emergency department with sudden-onset palpitations. He is hemodynamically stable with a blood pressure of 125/80 mmHg. A 12-lead electrocardiogram (ECG) reveals a sustained monomorphic ventricular tachycardia (SMVT) with a right bundle branch block pattern and left-axis deviation, which is diagnosed as an idiopathic fascicular ventricular tachycardia (VT). Which of the following is the most appropriate pharmacological therapy for acute conversion in this specific clinical scenario?

• ✓ Intravenous verapamil
• ○ Intravenous beta-blocker
• ○ Intravenous amiodarone
• ○ Intravenous lidocaine

Explanation. Intravenous verapamil is the recommended pharmacological treatment for the acute conversion of a known idiopathic fascicular ventricular tachycardia (VT).

Question 36

A 62-year-old male with a history of ischemic cardiomyopathy and an implantable cardioverter-defibrillator (ICD) presents to the emergency department after receiving five painful shocks from his device over the last hour. He is awake, alert, and hemodynamically stable with a blood pressure of 130/80 mmHg. A 12-lead electrocardiogram (ECG) reveals atrial fibrillation with a rapid ventricular response of 160 beats per minute. Telemetry indicates that the ICD is inappropriately interpreting the rapid atrial fibrillation as a ventricular arrhythmia, triggering the shocks. The hospital's electrophysiology specialist is unavailable and an ICD programmer cannot be immediately located. What is the most appropriate immediate intervention to halt the inappropriate therapies?

• ✓ Place a magnet over the ICD generator
• ○ Perform immediate synchronized external cardioversion
• ○ Administer intravenous amiodarone to chemically cardiovert the patient
• ○ Initiate advanced life support (ALS) protocols

Explanation. In cases where a patient is receiving inappropriate implantable cardioverter-defibrillator (ICD) shocks due to supraventricular tachycardias such as atrial fibrillation, the recommended action is to disable the ICD therapies. When an electrophysiology specialist or device programmer is not available to reprogram the device, the ICD therapies must be disabled by placing a magnet directly over the device.

Question 37

A 58-year-old woman with a history of non-ischemic cardiomyopathy and an implantable cardioverter-defibrillator (ICD) is admitted to the cardiac intensive care unit with an electrical storm. Over the last three hours, she has received 12 appropriate ICD shocks for recurrent ventricular tachycardia (VT). Despite treatment with intravenous amiodarone and propranolol, the ventricular arrhythmias and recurrent shocks persist. She is highly anxious and in severe psychological distress. What is the most appropriate next step to manage her intractable electrical storm?

• ✓ Deep sedation and intubation with mechanical ventilation
• ○ Discontinuation of propranolol and initiation of intravenous metoprolol
• ○ Immediate explantation of the ICD system
• ○ Administration of oral flecainide

Explanation. When an electrical storm remains intractable with multiple shocks occurring in a few hours despite available anti-arrhythmic therapies, deep sedation and intubation with mechanical ventilation should be utilized to alleviate psychological distress and abruptly decrease the pro-arrhythmogenic sympathetic tone that drives recurrent arrhythmias.

Question 38

A 68-year-old man with a history of ischemic cardiomyopathy (left ventricular ejection fraction 35%) and a dual-chamber implantable cardioverter-defibrillator (ICD) presents to the emergency department after receiving multiple device shocks over the past 24 hours. Interrogation of the ICD reveals incessant slow sustained monomorphic ventricular tachycardia (MVT) at a rate of 120 beats per minute, which is intermittently terminated by antitachycardia pacing but rapidly recurs. The patient remains hemodynamically stable during the episodes. What is the preferred primary management strategy for this patient's arrhythmia?

• ○ Initiation of intravenous amiodarone infusion
• ○ Administration of intravenous magnesium and potassium
• ✓ Catheter ablation
• ○ Initiation of an isoproterenol infusion

Explanation. In patients presenting with incessant slow monomorphic ventricular tachycardia, catheter ablation is the preferred treatment strategy over antiarrhythmic drug therapy. Sustained monomorphic ventricular tachycardia associated with structural heart disease is highly amenable to catheter ablation, and successful ablation is associated with a significant reduction in arrhythmia recurrence and improved long-term survival.

Question 39

A 65-year-old male with a history of ischemic cardiomyopathy presents with an electrical storm characterized by recurrent episodes of sustained ventricular tachycardia. Despite aggressive medical therapy with intravenous amiodarone and beta-blockers, the episodes are refractory. Catheter ablation is planned. A pre-procedural assessment reveals a high-risk PAINESD score. Which of the following is the most appropriate strategy regarding mechanical circulatory support for this procedure?

• ✓ Initiate prophylactic mechanical circulatory support prior to the ablation procedure.
• ○ Reserve mechanical circulatory support strictly for rescue use if hemodynamic collapse occurs during the ablation.
• ○ Withhold mechanical circulatory support entirely, as its application during ablation for electrical storm universally increases overall mortality.
• ○ Proceed directly to autonomic modulation, avoiding mechanical circulatory support and catheter ablation entirely.

Explanation. In patients suffering from electrical storm or who possess a high-risk PAINESD score, the use of prophylactic mechanical circulatory support treatment is associated with a substantially lower mortality rate. Providing this support prophylactically allows for hemodynamic stabilization and provides necessary circulatory support during the catheter ablation procedure.

Question 40

A 62-year-old man presents for a follow-up of newly diagnosed heart failure with reduced ejection fraction (HFrEF). His echocardiogram shows a left ventricular ejection fraction of 28%. He currently experiences New York Heart Association (NYHA) Class II symptoms. His home medications include carvedilol (a beta-blocker) and lisinopril (an angiotensin-converting enzyme inhibitor ). To optimally reduce his risk of mortality due to heart failure and sudden cardiac death (SCD), which of the following medication classes should be added to his current regimen?

• ✓ A mineralocorticoid receptor antagonist (MRA) and a sodium-glucose co-transporter 2 (SGLT2) inhibitor
• ○ A non-dihydropyridine calcium channel blocker and an anti-arrhythmic drug
• ○ An angiotensin receptor blocker (ARB) and a loop diuretic
• ○ Digoxin and a funny channel (If) inhibitor

Explanation. Optimal medical treatment of the underlying cardiac disease is mandatory in patients with HFrEF to reduce mortality due to heart failure and sudden cardiac death. The recommended foundational therapies include the combination of an angiotensin-converting enzyme inhibitor (ACE-I), angiotensin receptor blocker (ARB), or angiotensin receptor neprilysin inhibitor (ARNI); a beta-blocker; a mineralocorticoid receptor antagonist (MRA); and a sodium-glucose co-transporter 2 (SGLT2) inhibitor.

Question 41

A 65-year-old male with a history of coronary artery disease and left ventricular systolic dysfunction presents with highly symptomatic ventricular arrhythmias (VA). The cardiology team plans to initiate an antiarrhythmic drug (AAD) as adjunctive therapy to manage his symptoms. When considering the impact of various AADs on long-term prognosis, which of the following therapies is the only one that has demonstrated a reduction in all-cause mortality?

• ○ Amiodarone
• ✓ Beta-blockers
• ○ Sotalol
• ○ Flecainide

Explanation. Beta-blockers are the only class of antiarrhythmic drugs that have demonstrated a reduction in all-cause mortality in the management of ventricular arrhythmias.

Question 42

A 64-year-old woman with a history of recurrent symptomatic atrial fibrillation is started on quinidine (a sodium channel blocking agent) to maintain sinus rhythm. Her baseline electrocardiogram (ECG) demonstrates a normal sinus rhythm with a heart rate of 70 beats per minute, a QRS duration of 90 ms, and a corrected QT (QTc) interval of 440 ms. Two weeks later, she returns to the clinic for a routine follow-up ECG. The new ECG reveals a QTc interval of 515 ms, a QRS duration of 95 ms, and a normal PR interval. She currently feels well and reports no palpitations, dizziness, or syncope. Which of the following is the most appropriate next step in management?

• ○ Continue quinidine at the current dose and repeat the ECG in 4 weeks
• ✓ Discontinue the quinidine
• ○ Add an oral magnesium supplement and continue quinidine at the current dose
• ○ Switch therapy from quinidine to disopyramide

Explanation. Medications that prolong the QT interval require close electrocardiographic monitoring, particularly 1 to 2 weeks after initiation or an increase in dosage. The offending drug should be discontinued if the corrected QT (QTc) interval exceeds 500 ms, as this threshold places the patient at a significantly elevated risk for severe proarrhythmic side effects, such as torsades de pointes, regardless of whether the patient is currently asymptomatic.

Question 43

A 58-year-old male is recovering in the intensive care unit after surviving a sudden cardiac arrest due to ventricular fibrillation without an identifiable reversible cause. He is being counseled regarding the placement of an implantable cardioverter-defibrillator (ICD) for secondary prevention of sudden cardiac death. When discussing the expected benefits of an ICD compared to medical therapy alone, which of the following statements accurately reflects the expected mortality benefit?

• ✓ It provides an approximately 28% reduction in overall mortality, which is almost entirely due to a reduction in arrhythmic death.
• ○ It provides an approximately 50% reduction in overall mortality, primarily driven by a decrease in death from progressive heart failure.
• ○ It reduces overall mortality by 15%, with equal reductions seen in both arrhythmic and non-arrhythmic causes of death.
• ○ It reduces arrhythmic death by 72%, though it does not significantly decrease all-cause mortality due to competing risks.

Explanation. In patients surviving a cardiac arrest due to a ventricular arrhythmia, secondary prevention with an implantable cardioverter-defibrillator (ICD) compared to medical therapy yields a 28% mortality reduction, which is almost entirely attributable to the reduction of arrhythmic death.

Question 44

A 62-year-old female with a history of recurrent symptomatic atrial fibrillation is being evaluated for the initiation of an antiarrhythmic drug known to be associated with QT prolongation. Her medical history includes hypertension and diet-controlled type 2 diabetes mellitus. A baseline 12-lead electrocardiogram (ECG) demonstrates normal sinus rhythm, a heart rate of 68 beats per minute, and a corrected QT (QTc) interval of 518 ms. Her serum electrolytes, including potassium and magnesium, are within normal limits. Which of the following is the most appropriate course of action regarding the initiation of this drug?

• ○ Initiate the drug and perform a follow-up ECG after 1 day and again after 1 to 2 weeks.
• ✓ Do not initiate the drug.
• ○ Initiate the drug at a reduced dosage while providing continuous inpatient telemetry monitoring.
• ○ Initiate the drug because her baseline QTc is below the critical threshold of 550 ms.

Explanation. Initiating a medication associated with QT prolongation is strictly contraindicated when a patient has a baseline QTc interval greater than 500 ms.

Question 45

A 68-year-old woman with ischemic cardiomyopathy and a left ventricular ejection fraction of 28% despite optimal guideline-directed medical therapy is being evaluated for an implantable cardioverter-defibrillator (ICD) for the primary prevention of sudden cardiac death (SCD). When considering the evidence base for this intervention, which of the following is true regarding primary prevention ICDs in this demographic?

• ✓ Women have been underrepresented in primary prevention trials, and data suggest they may benefit less from the intervention.
• ○ Women have been equally represented in primary prevention trials, demonstrating identical survival benefits to men.
• ○ Women have been underrepresented in primary prevention trials, but data suggest they derive a significantly greater benefit from the intervention.
• ○ Women have been extensively studied in female-only primary prevention trials, confirming a superior reduction in non-arrhythmic death.

Explanation. Women have been historically underrepresented in all primary prevention implantable cardioverter-defibrillator (ICD) trials, and the available data suggest that they may derive less benefit from the device compared to their male counterparts.

Question 46

A 62-year-old woman with a history of non-ischemic dilated cardiomyopathy and a left ventricular ejection fraction (LVEF) of 28% is being evaluated for a primary prevention implantable cardioverter-defibrillator (ICD). She has a history of recurrent monomorphic ventricular tachycardia (VT) that occasionally causes mild palpitations but no severe hemodynamic compromise. During a shared decision-making discussion, she expresses a strong desire to avoid transvenous leads due to a friend's experience with a lead fracture. She asks if a subcutaneous ICD (S-ICD) would be an appropriate alternative. Based on her clinical presentation, what is the most significant limitation of choosing an S-ICD for this patient?

• ○ The S-ICD has a significantly higher rate of inappropriate shocks compared to transvenous systems.
• ✓ The S-ICD cannot deliver anti-tachycardia pacing (ATP).
• ○ The S-ICD is not indicated for primary prevention of sudden cardiac death.
• ○ The S-ICD cannot be utilized unless the patient has a low MADIT-ICD benefit score.

Explanation. The subcutaneous implantable cardioverter-defibrillator (S-ICD) lacks an intravascular lead and is therefore unable to deliver anti-tachycardia pacing (ATP), which is a crucial consideration for a patient with known recurrent monomorphic ventricular tachycardia who could benefit from painless termination of the arrhythmia.

Question 47

A 50-year-old woman with a history of non-ischemic dilated cardiomyopathy (left ventricular ejection fraction 25%) and New York Heart Association (NYHA) class II heart failure symptoms is evaluated for a primary prevention implantable cardioverter-defibrillator (ICD). She has no indication for antibradycardia pacing or cardiac resynchronization therapy. During shared decision-making, the cardiologist discusses the choice between a subcutaneous ICD (S-ICD) and a conventional transvenous ICD. Based on recent randomized trial data with a mean follow-up of 49 months in a similar demographic, what should the patient be told regarding the relative rates of device-related complications and inappropriate shocks between the two devices?

• ✓ The S-ICD is associated with a lower rate of device-related complications but a higher rate of inappropriate shocks compared to the transvenous ICD.
• ○ The S-ICD is associated with a higher rate of device-related complications but a lower rate of inappropriate shocks compared to the transvenous ICD.
• ○ The S-ICD is associated with higher rates of both device-related complications and inappropriate shocks compared to the transvenous ICD.
• ○ The S-ICD is associated with lower rates of both device-related complications and inappropriate shocks compared to the transvenous ICD.

Explanation. In a randomized trial comparing subcutaneous to transvenous ICDs, non-inferiority was shown for the primary composite endpoint of device-related complications and inappropriate shocks. However, looking at the individual components of that endpoint, the S-ICD group experienced a lower rate of device-related complications (5.9% vs 9.8%) but a higher rate of inappropriate shocks (9.7% vs 7.3%) when compared to the transvenous ICD group.

Question 48

A 50-year-old male with a history of myocardial infarction and a left ventricular ejection fraction of 30% presents with recurrent episodes of sustained monomorphic ventricular tachycardia (SMVT). Device interrogation from a previous wearable monitor indicates that his episodes are hemodynamically tolerated for brief periods. Electrophysiological evaluation suggests that his SMVT can be reliably terminated with anti-tachycardia pacing (ATP). The team is discussing the choice of device for secondary prevention of sudden cardiac death. Which of the following represents a major limitation of choosing a subcutaneous implantable cardioverter defibrillator (S-ICD) for this patient?

• ✓ It is incapable of delivering anti-tachycardia pacing (ATP) to terminate the SMVT.
• ○ It cannot effectively recognize and defibrillate sustained polymorphic VT (SPVT) or VF.
• ○ It is only approved for primary prevention of sudden cardiac death.
• ○ It requires concurrent cardiac resynchronization therapy (CRT) to function effectively.

Explanation. Subcutaneous implantable cardioverter defibrillators lack the capability to deliver anti-tachycardia pacing (ATP). For a patient with recurrent sustained monomorphic ventricular tachycardia that can be successfully pace-terminated, a transvenous system capable of ATP is preferred to prevent painful shocks.

Question 49

A 68-year-old male with a history of ischemic cardiomyopathy and a severely reduced left ventricular ejection fraction (LVEF) of 25% presents with fever, chills, and erythema over his implantable cardioverter-defibrillator (ICD) pocket. Blood cultures are positive for Staphylococcus aureus, and transesophageal echocardiography reveals a vegetation on the right ventricular lead. The patient undergoes complete transvenous extraction of the ICD system and is started on a 6-week course of intravenous antibiotics. Which of the following is the most appropriate management strategy for sudden cardiac death (SCD) prevention during his antibiotic therapy?

• ✓ Prescription of a wearable cardioverter defibrillator (WCD)
• ○ Routine monitoring with a 30-day external loop recorder
• ○ Immediate reimplantation of an epicardial ICD system
• ○ Initiation of prophylactic high-dose oral amiodarone therapy

Explanation. The wearable cardioverter defibrillator (WCD) is an external device that successfully detects and treats ventricular tachycardia and ventricular fibrillation. It provides necessary protection for patients who are at high risk for sudden cardiac death but are temporarily not candidates for an internal device implantation, such as those undergoing an extended course of antibiotic treatment following the extraction of an infected implantable cardioverter-defibrillator.

Question 50

A 62-year-old male with ischemic cardiomyopathy and a left ventricular ejection fraction of 28% undergoes implantation of a single-chamber implantable cardioverter defibrillator (ICD) for primary prevention. You are optimizing the device programming before the patient's discharge to minimize the burden of ICD therapy and improve patient outcomes. Which of the following programming strategies is most appropriate?

• ✓ A tachycardia detection strategy incorporating prolonged settings and high rate thresholds (e.g., ≥188 to >200 b.p.m.).
• ○ A tachycardia detection strategy incorporating short detection settings and low rate thresholds (e.g., >150 b.p.m.) to prevent syncope.
• ○ Customization of the bradycardia mode to ensure consistent right ventricular pacing for heart rate support.
• ○ A tachycardia detection strategy utilizing short detection durations combined with high rate thresholds.

Explanation. A tachycardia detection programming strategy incorporating prolonged settings and high rate thresholds reduces ICD therapies and all-cause mortality without increasing the risk of syncope. This benefit is particularly strong for primary prevention indications.

Question 51

A 58-year-old female with a history of anterior myocardial infarction and a left ventricular ejection fraction of 28% undergoes implantation of a dual-chamber implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death. She is in normal sinus rhythm and has intact atrioventricular conduction. The electrophysiologist is configuring the tachycardia detection and therapy zones to minimize inappropriate therapies and optimize painless termination of arrhythmias. Which of the following is the most appropriate programming strategy for this device?

• ○ Prioritization of ramp anti-tachycardia pacing (ATP) over burst ATP for the first attempt at tachycardia termination.
• ○ Utilization of a single-zone detection configuration to standardize therapy settings regardless of the tachycardia rate.
• ○ Avoidance of anti-tachycardia pacing (ATP) for very fast ventricular tachyarrhythmias to prevent an increase in arrhythmic syncope.
• ✓ Systematic use of burst anti-tachycardia pacing (ATP) prior to shock delivery, even for very fast ventricular tachyarrhythmias.

Explanation. Systematic use of anti-tachycardia pacing (ATP) before shock delivery for ventricular tachyarrhythmias, including those at very fast rates, effectively reduces the need for shock therapy without increasing the risk of arrhythmic syncope. Furthermore, burst ATP is the preferred modality for this purpose because it demonstrates greater efficacy in achieving initial tachycardia termination.

Question 52

A 54-year-old female with a non-ischemic cardiomyopathy and a single-chamber implantable cardioverter-defibrillator (ICD) presents to the emergency department after receiving three ICD shocks. Interrogation of the device shows the shocks were triggered by recurrent supraventricular tachycardia (SVT) exceeding the programmed therapy threshold. She is already on maximally tolerated doses of carvedilol. What is the most appropriate next step to prevent further inappropriate ICD therapies?

• ✓ Refer the patient for catheter ablation of the SVT.
• ○ Perform atrioventricular (AV) node ablation.
• ○ Initiate oral amiodarone to suppress the SVT.
• ○ Switch her beta-blocker from carvedilol to metoprolol.

Explanation. In patients experiencing inappropriate implantable cardioverter-defibrillator therapies due to recurrent supraventricular tachycardia, catheter ablation is the recommended first-line treatment because of its high success rate and low complication rate.

Question 53

A 62-year-old man with a history of non-ischemic cardiomyopathy and a left ventricular ejection fraction of 25% receives an implantable cardioverter defibrillator (ICD) for primary prevention. He presents for his first routine follow-up one month post-implantation. Device interrogation reveals normal function with no ventricular arrhythmias detected and no therapies delivered. During the visit, the patient notes he feels constantly "on edge" but assumes it is normal and will pass since the device has not actually fired yet. What is the most appropriate approach to his psychosocial management at this visit?

• ○ Reassure him that significant psychological distress primarily develops only after the first shock is delivered, so formal assessment can be deferred.
• ○ Defer psychological assessment until he develops clinically overt symptoms of severe depression, as early screening requires specialized psychiatric personnel.
• ○ Inform him that if he develops severe anxiety, cognitive behavioral therapy interventions are strictly contraindicated due to the risk of triggering arrhythmias.
• ✓ Perform an assessment of his ICD-related concerns now, as psychological distress is predominantly driven by the anticipation of potential shocks rather than having experienced one.

Explanation. Assessment of implantable cardioverter defibrillator (ICD) concerns is recommended in all ICD patients before shocks occur because psychological distress is mainly caused by the concern and anticipation of potentially receiving shocks rather than by having actually experienced one.

Question 54

A 58-year-old man with advanced ischemic cardiomyopathy recently underwent implantation of a continuous-flow left ventricular assist device (LVAD). His medical team is discussing whether he should undergo placement of an implantable cardioverter-defibrillator (ICD) for primary prevention. He has had occasional premature ventricular complexes but no sustained ventricular arrhythmias. When considering the survival benefits and risks of ICD placement in this specific patient population, which of the following statements is most accurate?

• ○ Routine ICD implantation is recommended for all continuous-flow LVAD recipients because it provides a documented survival benefit.
• ✓ ICD presence is not associated with prolonged survival in continuous-flow LVAD recipients, and the decision to implant should be individualized.
• ○ ICD placement is strictly contraindicated in continuous-flow LVAD carriers due to a prohibitive risk of device-device interaction.
• ○ ICD implantation significantly reduces mortality in this cohort, provided the device is programmed with high-rate cutoffs.

Explanation. Recent large registries have demonstrated that the presence of an implantable cardioverter-defibrillator (ICD) is not associated with prolonged survival in patients with continuous-flow left ventricular assist devices (LVADs). Because of the lack of a documented survival benefit, combined with the fact that these patients often tolerate ventricular arrhythmias and face associated risks from ICD placement such as infection and device interaction, an individualized approach is favored.

Question 55

A 60-year-old male with a prior anterior myocardial infarction and ischemic cardiomyopathy (left ventricular ejection fraction 25%) presents for primary prevention implantable cardioverter-defibrillator (ICD) implantation. He is in normal sinus rhythm, has no history of syncope, and does not require atrial or atrioventricular sequential pacing. The device will be implanted on the left side. In planning the procedure to minimize both short- and long-term complications, which of the following choices is most appropriate?

• ○ Obtaining venous access via the subclavian vein to minimize lead failure
• ○ Implanting a dual-chamber ICD to enhance supraventricular tachycardia discrimination
• ✓ Using a single-coil defibrillator lead
• ○ Using a dual-coil defibrillator lead to ensure adequate shock efficacy

Explanation. Routine use of single-coil defibrillator leads is favored due to a reduced risk of complications during future lead removal, without any associated differences in overall shock efficacy compared to dual-coil leads.

Question 56

An 82-year-old man with end-stage ischemic cardiomyopathy and metastatic lung cancer is transitioned to hospice care. He has an implantable cardioverter defibrillator (ICD) that was placed 5 years ago. He is pacemaker-dependent due to complete atrioventricular (AV) block. The patient and his family are asking about how to manage his ICD to ensure his comfort in his final days, as they are concerned about the potential for painful shocks. What is the most appropriate recommendation regarding his ICD management?

• ○ Deactivate both the shock therapies and the anti-bradycardia pacing therapy.
• ✓ Deactivate the shock therapies but continue the anti-bradycardia pacing therapy.
• ○ Maintain all current ICD therapies to prevent sudden arrhythmias from causing distress.
• ○ Surgically explant the device to completely eliminate the risk of therapies.

Explanation. In terminally ill patients, deactivating the shock therapies of an implantable cardioverter defibrillator is appropriate to prevent painful shocks at the end of life. However, deactivation of anti-bradycardia therapy is generally discouraged because it can lead to quality-of-life impairment from symptomatic bradycardia, and in some regions, it may be prohibited by law in pacemaker-dependent patients.

Question 57

A 62-year-old man with a history of non-ischemic dilated cardiomyopathy presents to the emergency department with palpitations and near-syncope. His 12-lead electrocardiogram (ECG) demonstrates a wide-complex tachycardia. He subsequently undergoes an electrophysiology study, which confirms the diagnosis of bundle branch reentrant ventricular tachycardia (BBR-VT). Which of the following is the most appropriate first-line therapy for managing this patient's arrhythmia?

• ○ Initiation of oral amiodarone
• ○ Optimization of beta-blocker therapy
• ✓ Catheter ablation
• ○ Initiation of oral sotalol

Explanation. Catheter ablation of bundle branch reentrant ventricular tachycardia (BBR-VT) is highly successful and is established as the definitive first-line therapy for managing this specific arrhythmia.

Question 58

A 58-year-old male with a history of a large anterior myocardial infarction 5 years ago due to Coronary Artery Disease (CAD) presents with recurrent episodes of sustained monomorphic Ventricular Tachycardia (VT) refractory to antiarrhythmic therapy. He is referred for catheter ablation. Based on the underlying structural heart disease, what are the expected electrophysiological characteristics of his VT circuit and the anticipated clinical outcome compared to a patient with a non-ischemic cardiomyopathy undergoing a similar procedure?

• ✓ The VT circuit is predominantly endocardial, and the clinical outcome of ablation is generally better than in patients with non-ischemic etiologies.
• ○ The VT circuit is predominantly epicardial or intramural, and the clinical outcome of ablation is generally worse than in patients with non-ischemic etiologies.
• ○ The VT circuit is predominantly endocardial, but the clinical outcome of ablation is generally worse than in patients with non-ischemic etiologies.
• ○ The VT circuit is predominantly epicardial or intramural, but the clinical outcome of ablation is generally better than in patients with non-ischemic etiologies.

Explanation. Post-infarct ventricular tachycardias are mainly related to an endocardial circuit, which makes them highly amenable to targeted endocardial ablation. This predictable endocardial location contributes significantly to better clinical outcomes following ablation in patients with ischemic structural heart disease compared to those with non-ischemic etiologies, where the circuits are more frequently intramural or epicardial and thus more challenging to ablate.

Question 59

A 62-year-old man with non-ischemic cardiomyopathy and recurrent ventricular tachycardia (VT) despite amiodarone therapy is referred for radiofrequency catheter ablation. He has a history of multiple implantable cardioverter-defibrillator (ICD) shocks. To optimize the procedure and guide mapping, the electrophysiology team is formulating a pre-procedural plan. Which of the following combinations of diagnostic data is most crucial for characterizing the arrhythmogenic substrate and determining the exit site of the arrhythmia prior to the procedure?

• ✓ 12-lead ECG documentation of the clinical VT and identification of myocardial scar using cardiac magnetic resonance (CMR) imaging or CT scan
• ○ Intraprocedural epicardial voltage mapping and coronary angiography to map the venous system
• ○ Transthoracic echocardiography to assess ejection fraction and routine Holter monitoring to quantify premature ventricular complexes (PVCs)
• ○ Empiric evaluation with bipolar/needle ablation or radiotherapy ablation during the initial mapping phase

Explanation. Optimizing the success of ventricular tachycardia ablation requires detailed pre-procedural planning to collect information about the arrhythmogenic substrate. Identifying myocardial scars using imaging modalities such as cardiac magnetic resonance (CMR) imaging or computed tomography (CT) scans, and determining the exit site of the ventricular arrhythmias using 12-lead ECG documentation of the clinical VTs or premature ventricular complexes (PVCs), are essential steps in this process.

Question 60

A 32-year-old woman with no past medical history presents with recurrent episodes of sustained palpitations. An electrocardiogram during an episode demonstrates a wide-complex tachycardia with a right bundle branch block morphology and left axis deviation. Echocardiography and cardiac magnetic resonance imaging reveal no structural heart disease. She is diagnosed with a verapamil-sensitive left fascicular ventricular tachycardia and undergoes an electrophysiology study for catheter ablation. Which of the following is the primary target for ablation in this patient's arrhythmia?

• ○ The earliest site of myocardial activation during the ventricular tachycardia
• ✓ Abnormal Purkinje tissue with diastolic activity during the ventricular tachycardia
• ○ Areas of low voltage indicating myocardial scar in the left ventricle
• ○ Cardiac autonomic ganglia associated with the left ventricular myocardium

Explanation. Verapamil-sensitive left fascicular ventricular tachycardias operate via a re-entrant mechanism involving the left ventricular Purkinje network. The appropriate target for catheter ablation in these specific arrhythmias is the abnormal Purkinje tissue demonstrating diastolic activity during the ventricular tachycardia.

Question 61

A 65-year-old woman is admitted to the cardiac intensive care unit with an acute anterior ST-segment elevation myocardial infarction (STEMI). She undergoes successful primary percutaneous coronary intervention (PCI) with a door-to-balloon time of 75 minutes. During the first 48 hours of her admission, the critical care team discusses her risk for developing ventricular arrhythmias (VA) and sudden cardiac death (SCD). Based on clinical and electrocardiographic (ECG) parameters, which of the following is an established independent predictor of VA in this setting?

• ✓ The sum of ST-segment deviations in all leads
• ○ A left ventricular ejection fraction (LVEF) greater than 40%
• ○ Hemodynamic stability prior to intervention
• ○ The presence of a late repolarization pattern on the ECG

Explanation. In patients presenting with acute coronary syndromes (both STEMI and non-STEMI), the sum of ST-segment deviations in all leads, hemodynamic instability, cardiogenic shock, and a left ventricular ejection fraction (LVEF) <40% are recognized as independent predictors of ventricular arrhythmias.

Question 62

A 62-year-old man arrives at the emergency department reporting severe, crushing substernal chest pain that began 45 minutes ago. His electrocardiogram (ECG) reveals an anterior ST-segment elevation myocardial infarction (STEMI). His blood pressure is 135/85 mmHg, and his heart rate is 92 beats per minute. He is immediately prepped for primary percutaneous coronary intervention (PCI). To specifically reduce the incidence of ventricular arrhythmias (VA) in the acute phase of his presentation, which of the following pharmacological strategies is most appropriate prior to PCI?

• ✓ Administration of early intravenous metoprolol.
• ○ Initiation of a prophylactic intravenous amiodarone infusion.
• ○ Administration of a prophylactic intravenous lidocaine bolus.
• ○ Withholding all beta-blocker therapy until after successful reperfusion.

Explanation. Early intravenous metoprolol administered before percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction reduces the incidence of arrhythmias in the acute phase and is safely tolerated without an increase in adverse events.

Question 63

A 65-year-old woman is admitted to the coronary care unit following primary percutaneous coronary intervention (PCI) for an inferior ST-segment elevation myocardial infarction (STEMI). Six hours post-procedure, she experiences multiple episodes of recurrent sustained polymorphic ventricular tachycardia (VT) accompanied by hypotension, which requires repeated electrical cardioversions to terminate. Which of the following is the most appropriate next step in management to assess the underlying cause of her recurrent arrhythmias?

• ✓ Immediate coronary angiography
• ○ Initiation of mechanical circulatory support
• ○ Intravenous procainamide infusion
• ○ Transvenous overdrive pacing

Explanation. Recurrent sustained ventricular tachycardia, particularly when polymorphic, or recurrent ventricular fibrillation in the setting of acute coronary syndrome indicates possible incomplete reperfusion or the recurrence of acute ischemia, for which immediate coronary angiography is indicated.

Question 64

A 62-year-old male presents with an acute ST-segment elevation myocardial infarction (STEMI) and undergoes successful primary percutaneous coronary intervention (PCI). Within 18 hours of the procedure, he experiences a sustained episode of monomorphic ventricular tachycardia (VT) that is successfully cardioverted. Another patient of the same age with a similar STEMI undergoes PCI but experiences an episode of ventricular fibrillation (VF) 18 hours post-procedure, which is successfully defibrillated. Both patients survive to hospital discharge. How does the long-term prognosis of the patient with early monomorphic VT compare to the patient with early VF?

• ✓ The patient with early monomorphic VT has a significantly higher risk of long-term mortality and a higher incidence of appropriate device interventions.
• ○ Both patients share an equally high risk of late sudden cardiac death, as all early ventricular arrhythmias heavily impact long-term prognosis.
• ○ The patient with early VF has a worse long-term prognosis because early VF is an independent predictor of 5-year all-cause mortality.
• ○ Neither early monomorphic VT nor early VF affects in-hospital mortality, but both predict equally poor long-term outcomes.

Explanation. Early monomorphic ventricular tachycardia (VT) occurring within the first 48 hours of an ST-segment elevation myocardial infarction (STEMI) is an independent predictor of death during long-term follow-up and is associated with a significantly higher incidence of adequate implantable cardioverter-defibrillator (ICD) interventions compared to early ventricular fibrillation (VF). While early VF increases in-hospital mortality, it is associated with a very low incidence of late sudden cardiac death, similar to that of VF-free patients, meaning the long-term prognosis is not significantly affected.

Question 65

A 62-year-old male presents with an anterior ST-segment elevation myocardial infarction (STEMI) and undergoes successful primary percutaneous coronary intervention (PCI). Prior to discharge, his left ventricular ejection fraction (LVEF) is estimated at 35% by echocardiography. He is initiated on optimal medical therapy. To determine the long-term need for prophylactic implantable cardioverter-defibrillator (ICD) implantation, when is the most appropriate time to repeat echocardiography to reassess his LVEF?

• ○ Within the first 2 weeks following the myocardial infarction (MI) to ensure early protection from sudden cardiac arrest.
• ○ At 4 weeks post-MI, as this is the standard timeframe to discriminate myocardial stunning from permanent damage.
• ✓ After the first 6 weeks post-MI, allowing for assessment in the post-remodelling phase.
• ○ Immediately prior to discharge, utilizing programmed electrical stimulation (PES) to guide immediate ICD placement.

Explanation. Assessment of the indication for prophylactic implantable cardioverter-defibrillator (ICD) implantation relies on accurate evaluation of left ventricular ejection fraction (LVEF) in the post-remodelling phase of a myocardial infarction (MI). Reassessing LVEF after the first 6 weeks in patients with a pre-discharge LVEF of 40% or less ensures that the evaluation effectively discriminates between transient myocardial stunning and true reverse remodelling, which correlates with significantly lower rates of sudden cardiac arrest and death.

Question 66

A 62-year-old male is admitted to the coronary care unit following an acute anterior ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). On day 3 post-MI, he develops an electrical storm with recurrent episodes of polymorphic ventricular tachycardia (PVT) requiring multiple electrical cardioversions. Repeat coronary angiography reveals no evidence of recurrent ischemia. Despite treatment with optimal doses of a beta-blocker and intravenous amiodarone, the episodes of PVT continue to recur. Which of the following is the most appropriate next pharmacological step to suppress the recurrent arrhythmias?

• ○ Add sotalol
• ✓ Add quinidine
• ○ Add lidocaine
• ○ Add flecainide

Explanation. In the early post-myocardial infarction phase, if polymorphic ventricular tachycardia recurs despite treatment with a beta-blocker and amiodarone, suppression of the arrhythmia can be achieved with quinidine therapy.

Question 67

A 48-year-old woman is brought to the emergency department after experiencing a sudden cardiac arrest while resting. She was successfully resuscitated from ventricular fibrillation. Coronary angiography reveals no obstructive atherosclerotic disease, but provocation testing demonstrates severe focal coronary vasospasm accompanied by ST-segment elevation, confirming the diagnosis of variant angina. She is initiated on a high-dose calcium channel blocker. Which of the following is the most appropriate additional step for long-term prevention of sudden cardiac death in this patient?

• ○ Initiate therapy with a beta-blocker to suppress further ventricular arrhythmias
• ✓ Proceed with the implantation of an implantable cardioverter-defibrillator (ICD)
• ○ Perform an electrophysiology study to stratify risk before further intervention
• ○ Prescribe prophylactic oral amiodarone to prevent recurrent ventricular fibrillation

Explanation. In patients who survive sudden cardiac arrest secondary to coronary vasospasm (variant angina), medical therapy with calcium channel blockers and other vasodilators may not provide sufficient protection against recurrent life-threatening ventricular arrhythmias. Therefore, placement of an implantable cardioverter-defibrillator should still be considered to reduce the risk of sudden cardiac death.

Question 68

A 62-year-old male with ischemic cardiomyopathy and a left ventricular ejection fraction of 28% is evaluated in the clinic. He is currently on optimal medical therapy including beta-blockers, sodium-glucose cotransporter-2 inhibitors, and an angiotensin receptor-neprilysin inhibitor. You are discussing the potential placement of an implantable cardioverter-defibrillator (ICD) for the primary prevention of sudden cardiac death. He asks about the actual benefit of the device, noting that his medications already lower his risk of dying. Based on recent large prospective registry data, what is the consistent relative reduction in mortality provided by an ICD in heart failure patients, despite the use of modern medical therapy and early revascularization?

• ○ A relative reduction of 12%
• ✓ A relative reduction of 27%
• ○ A relative reduction of 42%
• ○ A relative reduction of 55%

Explanation. Although early revascularization strategies and modern heart failure medications have reduced the overall risk of sudden cardiac death and total mortality in heart failure patients, the relative reduction in mortality provided by an implantable cardioverter-defibrillator remains a consistent 27%.

Question 69

A 62-year-old man presents to the clinic for evaluation of a single episode of syncope that occurred without warning while he was sitting on the couch. He has a history of a myocardial infarction 4 months ago. His current medications include aspirin, atorvastatin, bisoprolol, and ramipril. Echocardiography shows a left ventricular ejection fraction of 46%. A thorough non-invasive evaluation, including a 14-day continuous ambulatory electrocardiogram monitor and an exercise stress test, fails to reveal an etiology for his syncope. Which of the following is the most appropriate next step in the management of this patient?

• ○ Proceed to empirical implantation of an implantable cardioverter-defibrillator (ICD).
• ○ Initiate prophylactic amiodarone therapy to prevent sudden cardiac death.
• ✓ Perform programmed electrical stimulation (PES).
• ○ Implant an implantable loop recorder (ILR) for long-term monitoring.

Explanation. In post-myocardial infarction patients with preserved or mildly reduced left ventricular ejection fraction in whom syncope remains unexplained after non-invasive evaluation, programmed electrical stimulation (PES) is recommended to identify an arrhythmic substrate and guide subsequent management.

Question 70

A 65-year-old male with a history of coronary artery disease and a prior myocardial infarction presents to the emergency department experiencing palpitations. The electrocardiogram reveals a sustained monomorphic ventricular tachycardia. During the episode, his blood pressure is 125/80 mmHg, and he remains fully conscious and conversational. A recent echocardiogram documents a left ventricular ejection fraction of 45%. Which of the following is an appropriate management strategy for this patient's arrhythmia?

• ✓ Catheter ablation as first-line therapy without implantable cardioverter-defibrillator back-up
• ○ Mandatory implantable cardioverter-defibrillator implantation prior to considering any catheter-based interventions
• ○ Immediate surgical left ventricular aneurysmectomy
• ○ Strict avoidance of catheter ablation due to the hemodynamically well-tolerated nature of the arrhythmia

Explanation. Catheter ablation is an established treatment option for hemodynamically well-tolerated ventricular tachycardia in selected post-myocardial infarction patients with preserved or mildly reduced ejection fraction (ejection fraction > 40%). Due to improvements in ablation and imaging technologies, this procedure can be utilized as a first-line therapy for these specific patients, even without implantable cardioverter-defibrillator back-up.

Question 71

A 62-year-old man presents to the emergency department with palpitations and mild lightheadedness. An electrocardiogram (ECG) shows sustained monomorphic ventricular tachycardia (SMVT) at 155 bpm. His blood pressure is 118/76 mmHg, and he remains hemodynamically stable. Following successful cardioversion, an echocardiogram demonstrates a mildly reduced left ventricular ejection fraction (LVEF) of 48%. Coronary angiography reveals no obstructive coronary artery disease. Which of the following statements regarding his long-term management is most accurate?

• ✓ Either implantable cardioverter-defibrillator (ICD) implantation or catheter ablation at an experienced center should be considered.
• ○ ICD implantation is the definitive therapy, as secondary prevention trials have shown a significant survival benefit in patients with an LVEF ≥35%.
• ○ Catheter ablation is strictly superior to ICD implantation, as it has been shown to significantly reduce overall mortality in this specific patient population.
• ○ Revascularization alone, if coronary artery disease had been found, would be sufficient to prevent future VT recurrences.

Explanation. In patients with a preserved or mildly reduced left ventricular ejection fraction presenting with hemodynamically tolerated sustained monomorphic ventricular tachycardia, data indicate that either ICD implantation or catheter ablation performed in experienced centers should be considered. Retrospective studies comparing catheter ablation to ICD implantation in this population have demonstrated that overall mortality does not differ significantly between the two strategies.

Question 72

A 68-year-old male with a history of coronary artery disease and prior myocardial infarction has an implantable cardioverter-defibrillator (ICD) in place. He is currently maintained on amiodarone for the suppression of sustained monomorphic ventricular tachycardia (SMVT). He presents to the cardiology clinic after receiving two appropriate ICD shocks over the past week for recurrent SMVT. Device interrogation confirms the arrhythmias. What is the most appropriate next step in the management of this patient's recurrent ventricular arrhythmia?

• ✓ Refer the patient for catheter ablation of the ventricular tachycardia.
• ○ Escalate antiarrhythmic drug therapy by increasing the amiodarone dose.
• ○ Add sotalol to his current antiarrhythmic medical regimen.
• ○ Defer further intervention until the patient experiences at least three appropriate ICD shocks.

Explanation. In patients with coronary artery disease who experience recurrent sustained monomorphic ventricular tachycardia while on amiodarone treatment, catheter ablation is recommended over the escalation of antiarrhythmic drug therapy. Catheter ablation significantly reduces the composite endpoint of death, ventricular tachycardia storm, and appropriate implantable cardioverter-defibrillator therapy in this specific clinical scenario.

Question 73

A 28-year-old asymptomatic male marathon runner is evaluated following an incidental murmur heard during a routine physical examination. A computed tomography angiography (CTA) reveals an anomalous aortic origin of the left coronary artery arising from the right sinus of Valsalva. The anomalous vessel demonstrates an interarterial course between the aorta and the pulmonary artery. To definitively determine the indication for surgical intervention in this asymptomatic patient, what is the most appropriate next step in evaluation?

• ○ Immediate surgical correction based solely on the high-risk anatomic findings.
• ✓ Assessment of exercise-induced ischemia using advanced cardiac stress imaging.
• ○ Implantation of an implantable cardioverter-defibrillator (ICD) for primary prevention.
• ○ Serial monitoring with a resting 12-lead electrocardiogram (ECG) and a 24-hour Holter monitor.

Explanation. Indications for surgical intervention in an asymptomatic patient with an anomalous aortic origin of a coronary artery require both the evaluation of high-risk anatomic features (such as an interarterial course, slit-like orifice, or acute-angle take-off) and the assessment of exercise-induced ischemia utilizing advanced cardiac stress imaging modalities.

Question 74

A 38-year-old male patient presents with recurrent palpitations. He has no significant past medical history, and his physical examination is unremarkable. A 12-lead electrocardiogram (ECG) shows sinus rhythm with multiform premature ventricular complexes (PVCs) and subtle T-wave changes. A transthoracic echocardiogram demonstrates normal left ventricular systolic function, but the study is technically difficult due to poor acoustic windows, and the evaluation of the right ventricle is inconclusive. A 24-hour Holter monitor reveals a PVC burden of 18%. Which of the following is the most appropriate next step to evaluate for underlying structural heart disease?

• ✓ Cardiac magnetic resonance imaging
• ○ Signal-averaged electrocardiogram
• ○ Invasive coronary angiography
• ○ Exercise stress echocardiography

Explanation. Cardiac magnetic resonance imaging is recommended to rule out underlying structural heart disease whenever electrocardiography and echocardiography are inconclusive, or if the clinical presentation raises suspicion for structural heart disease.

Question 75

A 28-year-old man presents with bothersome palpitations that primarily occur when he is jogging or playing tennis. A 24-hour Holter monitor reveals a high burden of monomorphic premature ventricular complexes (PVCs) that markedly increase in frequency during periods of elevated heart rate and physical exertion. A transthoracic echocardiogram shows normal biventricular size and function with no evidence of structural heart disease. Which of the following is the most appropriate initial pharmacological therapy to suppress this patient's arrhythmia?

• ✓ Metoprolol
• ○ Verapamil
• ○ Flecainide
• ○ Amiodarone

Explanation. Beta-blockers are the preferred initial pharmacological therapy for suppressing idiopathic premature ventricular complexes when there is a correlation demonstrating a higher burden of the arrhythmia associated with elevated heart rates or during physical exercise.

Question 76

A 32-year-old woman presents with frequent, symptomatic palpitations. A 24-hour Holter monitor reveals a 25% burden of premature ventricular complexes (PVCs). A 12-lead electrocardiogram (ECG) captures the PVCs, demonstrating a left bundle branch block morphology with an inferior axis, which is indicative of a right ventricular outflow tract (RVOT) origin. Her echocardiogram shows normal ventricular function and no structural abnormalities. What is the most appropriate first-line therapy for this patient's arrhythmia?

• ✓ Catheter ablation
• ○ Oral amiodarone therapy
• ○ Oral flecainide therapy
• ○ Implantable cardioverter-defibrillator (ICD) placement

Explanation. Catheter ablation is the recommended first-line therapy for idiopathic right ventricular outflow tract (RVOT) premature ventricular complexes (PVCs). Clinical evidence demonstrates that catheter ablation is superior to antiarrhythmic drug therapy for arrhythmia suppression in patients with RVOT PVCs, achieving high success rates with rare procedural complications.

Question 77

A 34-year-old male is evaluated in the cardiology clinic for incidentally noted premature ventricular complexes (PVCs) on an electrocardiogram (ECG) performed for life insurance purposes. He is completely asymptomatic, exercises regularly, and denies palpitations, presyncope, or dyspnea. A 24-hour Holter monitor demonstrates a monomorphic PVC burden of 15%. A transthoracic echocardiogram reveals a structurally normal heart with a left ventricular ejection fraction (LVEF) of 62%. What is the most appropriate management plan for this patient?

• ✓ Reassurance and regular assessment of the left ventricular ejection fraction.
• ○ Referral for radiofrequency catheter ablation of the PVC focus.
• ○ Initiation of a beta-blocker to reduce the PVC burden and prevent cardiomyopathy.
• ○ Initiation of a class IC antiarrhythmic drug to suppress the ectopic ventricular activity.

Explanation. For asymptomatic patients with a premature ventricular complex (PVC) burden greater than 10% and preserved ventricular function, there is no established benefit to initiating antiarrhythmic medication or catheter ablation. Because a PVC burden of 10% or greater represents the minimal threshold associated with the potential future development of left ventricular dysfunction, the appropriate management is regular assessment of the left ventricular ejection fraction.

Question 78

A 52-year-old female presents with palpitations and progressive fatigue. An electrocardiogram (ECG) reveals a high burden of premature ventricular complexes (PVCs) originating from the right ventricular outflow tract (RVOT). Echocardiography demonstrates a left ventricular ejection fraction (LVEF) of 42%, consistent with moderate left ventricular (LV) dysfunction, suspected to be PVC-induced cardiomyopathy. She has not tolerated beta-blockers or calcium channel blockers (CCBs) due to symptomatic hypotension. Which of the following anti-arrhythmic medications is an appropriate pharmacological option to consider next in this specific clinical scenario?

• ✓ Flecainide
• ○ Amiodarone
• ○ Dofetilide
• ○ Dronedarone

Explanation. Flecainide is an appropriate pharmacological therapy that can be considered for the management of premature ventricular complex (PVC)-induced cardiomyopathy in selected patients who have only moderate left ventricular (LV) dysfunction.

Question 79

A 48-year-old male with no prior cardiac history is evaluated for an asymptomatic reduction in left ventricular ejection fraction (LVEF) to 42% discovered on a routine echocardiogram. Coronary angiography reveals normal coronary arteries. A 24-hour Holter monitor demonstrates a premature ventricular complex (PVC) burden of 6%. Which of the following is the most appropriate next step in the evaluation of this patient's cardiomyopathy?

• ✓ Suspect an alternative etiology for the cardiomyopathy, pursue further diagnostic work-up, and repeat the Holter monitor.
• ○ Diagnose PVC-induced cardiomyopathy and refer the patient for immediate PVC catheter ablation.
• ○ Attribute the LVEF reduction definitively to the PVCs and initiate therapy with a class IC antiarrhythmic agent.
• ○ Reassure the patient that his LV dysfunction will resolve spontaneously without intervention since his PVC burden is below 20%.

Explanation. A PVC burden of at least 10% is generally considered the minimal threshold for the development of PVC-induced cardiomyopathy. In patients with left ventricular dysfunction and a PVC burden of less than 10%, other etiologies for the cardiomyopathy should be strongly suspected and further diagnostic work-up undertaken. Additionally, because day-to-day fluctuations in PVC burden can occur, repeating the Holter monitor is indicated to accurately assess these variations.

Question 80

A 45-year-old male is evaluated for recent-onset exertional dyspnea. Echocardiography demonstrates a left ventricular ejection fraction (LVEF) of 38%. A 24-hour Holter monitor reveals a 22% burden of monomorphic premature ventricular complexes (PVCs). The cardiologist is evaluating whether the patient has pure PVC-induced cardiomyopathy or underlying structural heart disease (SHD) aggravated by frequent PVCs. Which of the following baseline characteristics would most strongly favor a diagnosis of pure PVC-induced cardiomyopathy rather than PVC-aggravated cardiomyopathy?

• ✓ A smaller left ventricular end-diastolic diameter and a shorter intrinsic QRS duration.
• ○ The presence of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging.
• ○ PVCs exhibiting a predominant right bundle branch block (RBBB) morphology on electrocardiogram.
• ○ A severely dilated left ventricle with an intrinsic QRS duration of 150 milliseconds.

Explanation. Parameters such as a smaller left ventricular end-diastolic diameter and a shorter intrinsic QRS duration are key clinical features that indicate less underlying baseline structural derangement, thereby pointing toward pure premature ventricular complex (PVC)-induced cardiomyopathy.

Question 81

A 42-year-old male presents with palpitations and progressively decreasing exercise tolerance. A 24-hour Holter monitor demonstrates a monomorphic premature ventricular complex (PVC) burden of 22%. Echocardiography reveals a newly reduced left ventricular ejection fraction (LVEF) of 44%. Cardiac magnetic resonance (CMR) imaging shows no late gadolinium enhancement (LGE). He is scheduled for catheter ablation for presumed PVC-induced cardiomyopathy. Which of the following features is associated with the highest rate of acute ablation success and favorable clinical outcome in such patients?

• ✓ Origin of the premature ventricular complexes from the ventricular outflow tract
• ○ Origin of the premature ventricular complexes from the left ventricular epicardium
• ○ Presence of multiple varying premature ventricular complex morphologies
• ○ Presence of late gadolinium enhancement on cardiac magnetic resonance imaging

Explanation. Factors that positively influence both the acute success of catheter ablation and long-term clinical outcomes for premature ventricular complexes (PVCs) include an outflow tract site of origin, a lower number of PVC morphologies, and the absence of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging.

Question 82

A 28-year-old man presents with palpitations and progressive shortness of breath. Echocardiography shows a dilated cardiomyopathy phenotype with a reduced left ventricular ejection fraction of 38%. A 24-hour Holter monitor reveals a premature ventricular complex (PVC) burden of 18%, featuring numerous PVCs with both right bundle branch block (RBBB) and left bundle branch block (LBBB) morphologies. Genetic testing reveals a pathogenic gain-of-function mutation in the SCN5A gene. Based on this patient's presentation, which of the following describes the underlying pathophysiologic mechanism and an appropriate pharmacological therapy?

• ✓ Hyperexcitability of the fascicular Purkinje system; therapy with flecainide
• ○ Hypoexcitability of the fascicular Purkinje system; therapy with isoproterenol
• ○ Abnormal calcium handling in the ventricular myocardium; therapy with verapamil
• ○ Sympathetic overdrive of the sinoatrial node; therapy with metoprolol

Explanation. The patient's presentation of a dilated cardiomyopathy phenotype, high premature ventricular complex (PVC) burden with right bundle branch block (RBBB) and left bundle branch block (LBBB) morphologies, and an SCN5A gain-of-function mutation is characteristic of multifocal ectopic Purkinje-related premature contractions. This condition is driven by a gain of function of the sodium channel, leading to hyperexcitability of the fascicular Purkinje system. These patients generally do not respond to beta-blockers but may benefit from therapy with flecainide, quinidine, or amiodarone.

Question 83

A 48-year-old man presents with progressive dyspnea on exertion and fatigue over the past 6 months. An echocardiogram reveals a left ventricular ejection fraction of 35% with global hypokinesis and left ventricular dilatation. Coronary angiography shows no obstructive coronary artery disease. A 24-hour Holter monitor demonstrates a 28% premature ventricular complex (PVC) burden, and the PVCs are predominantly monomorphic. The patient is suspected to have a cardiomyopathy caused by the frequent PVCs. Which of the following is the most appropriate next step in the management of his arrhythmia?

• ✓ Catheter ablation
• ○ Initiation of flecainide
• ○ Initiation of amiodarone
• ○ Implantation of a cardiac resynchronization therapy (CRT) device

Explanation. In patients with a cardiomyopathy suspected to be caused by frequent and predominately monomorphic premature ventricular complexes, catheter ablation is recommended.

Question 84

A 38-year-old man presents with progressive dyspnea and fatigue. Echocardiography reveals a dilated left ventricle with a reduced ejection fraction of 38%. His 12-lead electrocardiogram (ECG) shows a first-degree atrioventricular (AV) block. His family history is significant for a father who died suddenly of an unknown cardiac issue at age 45. Genetic testing is planned. Based on his clinical presentation, a mutation in which of the following genes is highly suspected, and what are its prognostic implications regarding ventricular arrhythmias (VA) and sudden cardiac death (SCD)?

• ✓ LMNA; associated with a high rate of VA and SCD that can be independent of left ventricular ejection fraction.
• ○ TTN; associated with the highest overall frequency of mutations and the highest rate of VA and SCD.
• ○ FLNC; associated with prolonged AV conduction and a low risk of VA and SCD.
• ○ PLN; associated with the highest rate of VA and SCD, strongly dependent on left ventricular ejection fraction.

Explanation. The clinical presentation of dilated cardiomyopathy at a young age, particularly with signs such as prolonged AV conduction and a family history of premature sudden cardiac death, is highly suspicious for an inherited etiology involving a mutation in the LMNA gene. LMNA mutations are known to be associated with a high rate of ventricular arrhythmias and sudden cardiac death, and this elevated risk is observed to be independent of the patient's left ventricular ejection fraction.

Question 85

A 48-year-old woman with a diagnosis of non-ischemic dilated cardiomyopathy (DCM) undergoes a cardiac magnetic resonance (CMR) scan for further risk stratification. She is currently asymptomatic on optimal medical therapy, and her most recent echocardiogram shows a left ventricular ejection fraction (LVEF) of 42%. Which of the following findings on her CMR would be most strongly and specifically associated with an increased risk for sudden cardiac death (SCD) and arrhythmic endpoints?

• ✓ Presence of late gadolinium enhancement (LGE)
• ○ Left ventricular end-diastolic volume index > 100 mL/m2
• ○ Impaired right ventricular ejection fraction
• ○ Transmural myocardial edema on T2-weighted imaging

Explanation. In patients with dilated cardiomyopathy, the presence of late gadolinium enhancement on cardiac magnetic resonance imaging is a strong predictor of arrhythmic endpoints and sudden cardiac death risk. This association remains highly significant even in patients who have a mildly reduced left ventricular ejection fraction greater than 35%.

Question 86

A 35-year-old male presents for a routine clinical evaluation. He was recently diagnosed with a dilated cardiomyopathy (DCM) phenotype secondary to an LMNA (Lamin A/C) non-missense mutation. An echocardiogram reveals a left ventricular ejection fraction (LVEF) of 42%. A 24-hour Holter monitor demonstrates several runs of non-sustained ventricular tachycardia (NSVT) and first-degree atrioventricular (AV) block. Using a validated clinical calculator, his 5-year estimated risk of life-threatening ventricular arrhythmias is determined to be 14%. The patient is an amateur endurance athlete and asks if he can safely resume training for an upcoming marathon. Which of the following is the most appropriate recommendation regarding his management?

• ○ Consider primary prevention implantable cardioverter-defibrillator (ICD) implantation and clear him for high-intensity exercise once the device is implanted.
• ✓ Consider primary prevention implantable cardioverter-defibrillator (ICD) implantation and advise against high-intensity exercise.
• ○ Defer implantable cardioverter-defibrillator (ICD) implantation as he has no history of sustained ventricular arrhythmias, but advise against high-intensity exercise.
• ○ Defer implantable cardioverter-defibrillator (ICD) implantation and clear him to resume high-intensity marathon training.

Explanation. In patients with an LMNA mutation, primary prevention implantable cardioverter-defibrillator (ICD) implantation should be considered when the estimated 5-year risk of life-threatening ventricular arrhythmias is 10% or greater and there is a manifest cardiac phenotype, such as non-sustained ventricular tachycardia (NSVT), a left ventricular ejection fraction (LVEF) of less than 50%, or atrioventricular (AV) conduction delay. This patient meets these criteria for device implantation due to his 14% 5-year calculated risk combined with an LVEF of 42%, the presence of NSVT, and AV block. Furthermore, high-intensity exercise is associated with a high risk of sudden cardiac death and impaired LVEF in LMNA mutation carriers with a dilated cardiomyopathy phenotype, and is therefore not recommended.

Question 87

A 48-year-old male with known dilated cardiomyopathy (DCM) and a left ventricular ejection fraction (LVEF) of 44% on optimal medical therapy presents after an episode of unexplained syncope. His 12-lead electrocardiogram reveals normal sinus rhythm without conduction abnormalities, and initial workup is unremarkable. Which of the following approaches is most appropriate for assessing his risk of sudden cardiac death (SCD) and guiding the decision for an implantable cardioverter-defibrillator (ICD)?

• ○ Proceed directly to ICD implantation because unexplained syncope confers a high SCD risk regardless of LVEF.
• ✓ Perform programmed electrical stimulation (PES).
• ○ Recommend placement of an implantable loop recorder, as patients with LVEF ≥40% do not benefit from ICDs.
• ○ Rely solely on a 24-hour Holter monitor to detect non-sustained ventricular tachycardia before considering an ICD.

Explanation. In patients with dilated cardiomyopathy and a mildly reduced ejection fraction (≥40%) who experience unexplained syncope, programmed electrical stimulation (PES) provides significant incremental prognostic value. Those who are inducible during PES have a high likelihood of experiencing ventricular arrhythmias requiring appropriate ICD therapy, whereas non-inducible patients have a very low risk of sudden cardiac death or symptomatic ventricular arrhythmias.

Question 88

A 72-year-old male with non-ischemic dilated cardiomyopathy (left ventricular ejection fraction 28%) and New York Heart Association (NYHA) class II heart failure presents for a follow-up. He is treated with an angiotensin-converting enzyme inhibitor, a beta-blocker, and a mineralocorticoid receptor antagonist at target doses. The patient and his family are asking about the potential benefits of an implantable cardioverter-defibrillator (ICD) for primary prevention. What is the most accurate information to provide regarding his expected outcome with an ICD?

• ○ An ICD is associated with a significant reduction in all-cause mortality in patients of his age group.
• ✓ An ICD significantly reduces the risk of sudden cardiac death, but is not associated with a reduction in all-cause mortality in patients older than 70 years of age.
• ○ An ICD does not reduce the risk of sudden cardiac death in patients who are adequately treated with optimal medical therapy including a mineralocorticoid receptor antagonist.
• ○ An ICD decreases all-cause mortality in older patients specifically because of their higher baseline risk of sudden cardiac death.

Explanation. In patients with non-ischemic dilated cardiomyopathy on optimal medical therapy, data demonstrates that while an implantable cardioverter-defibrillator (ICD) significantly reduces the rate of sudden cardiac death, it does not translate to a reduction in all-cause mortality for patients over 70 years of age. A significant reduction in all-cause mortality with ICD therapy is specifically observed in younger patients (≤70 years of age).

Question 89

A 45-year-old man with hypokinetic non-dilated cardiomyopathy (HNDCM) presents for a routine follow-up. His left ventricular ejection fraction (LVEF) is 42% despite optimal medical therapy. He reports a recent episode of unexplained syncope while walking his dog. Cardiac magnetic resonance (CMR) imaging reveals the presence of late gadolinium enhancement (LGE), and genetic testing identifies a pathogenic mutation in the FLNC gene. What is the most appropriate next step in the management of this patient's sudden cardiac death risk?

• ✓ Implant an implantable cardioverter-defibrillator (ICD)
• ○ Reassure the patient and continue current medical therapy as his LVEF is >35%
• ○ Initiate amiodarone therapy for primary prevention of ventricular arrhythmias
• ○ Perform an electrophysiology study and only implant an ICD if sustained monomorphic ventricular tachycardia (SMVT) is induced

Explanation. In patients with dilated cardiomyopathy or hypokinetic non-dilated cardiomyopathy who have intermediate left ventricular dysfunction, relying solely on left ventricular ejection fraction is limited for accurate risk stratification. The presence of a combination of risk markers strongly associated with ventricular arrhythmias and sudden cardiac death—such as late gadolinium enhancement on cardiac magnetic resonance, specific pathogenic mutations (e.g., FLNC, PLN, RBM20), and unexplained syncope—indicates that an implantable cardioverter-defibrillator should be considered.

Question 90

A 54-year-old male with a known history of non-ischaemic dilated cardiomyopathy (DCM) and a left ventricular ejection fraction of 40% presents to the emergency department complaining of palpitations. His electrocardiogram (ECG) shows a sustained monomorphic ventricular tachycardia (VT) at a rate of 150 bpm. His blood pressure is 120/80 mmHg, and he is alert, comfortable, and without chest pain or dyspnoea. After successful cardioversion to sinus rhythm, which of the following is the most appropriate recommendation regarding long-term arrhythmic management for this patient?

• ✓ Placement of an implantable cardioverter-defibrillator (ICD).
• ○ Long-term administration of amiodarone to suppress further VT.
• ○ Immediate catheter ablation of the VT without ICD placement.
• ○ Observation and optimization of guideline-directed medical therapy for heart failure alone.

Explanation. In patients with non-ischaemic dilated cardiomyopathy who present with haemodynamically tolerated sustained ventricular tachycardia, an implantable cardioverter-defibrillator (ICD) should be considered. The arrhythmogenic substrate in dilated cardiomyopathy is typically less well-defined, and the ongoing potential for disease progression warrants ICD placement to reduce the risk of arrhythmic death.

Question 91

A 34-year-old man presents with palpitations and presyncope during exertion. His 12-lead electrocardiogram (ECG) reveals T-wave inversions in leads V1-V3 and frequent premature ventricular complexes. He is referred for cardiac magnetic resonance (CMR) imaging for suspected arrhythmogenic right ventricular cardiomyopathy (ARVC). Which of the following statements best describes the CMR findings and their relation to the diagnostic criteria for this condition?

• ○ Tissue characterization demonstrating right ventricular fatty infiltration is a mandatory major criterion in the 2010 revised diagnostic task force criteria.
• ○ The presence of biventricular involvement rules out the diagnosis, as the disease strictly isolates to the right ventricle.
• ✓ Right ventricular fatty infiltration and left ventricular late gadolinium enhancement may be present before patients meet major task force imaging criteria.
• ○ Left ventricular late gadolinium enhancement only occurs in the end-stage phase of the disease and is not seen in early evaluations.

Explanation. Right ventricular fatty infiltration and left ventricular late gadolinium enhancement are frequently observed in patients with arrhythmogenic right ventricular cardiomyopathy and may be present even before they meet the major task force imaging criteria.

Question 92

A 24-year-old male presents for a cardiovascular evaluation. His brother was recently diagnosed with arrhythmogenic right ventricular cardiomyopathy (ARVC). Genetic testing revealed that the patient carries the same pathogenic mutation as his brother. Currently, the patient is completely asymptomatic. Comprehensive testing, including an electrocardiogram (ECG), Holter monitor, and cardiac magnetic resonance imaging, reveals no structural or electrical abnormalities, indicating no clinical disease expression. The patient is an avid athlete and asks for advice regarding his participation in competitive sports. Based on the current understanding of ARVC, which of the following is the most appropriate recommendation?

• ○ He can continue unrestricted competitive sports because he currently lacks phenotypic disease expression.
• ✓ Avoidance of competitive, high-intensity exercise is reasonable despite the absence of clinical disease expression.
• ○ He should be restricted from all physical activity, including low-intensity recreational sports, to prevent disease penetrance.
• ○ He can participate in competitive, high-intensity exercise only if he is initiated on prophylactic therapy with atenolol.

Explanation. Restriction from high-intensity exercise is a recognized preventive tool to reduce the risk of ventricular arrhythmias and disease progression in ARVC. For mutation carriers who do not yet exhibit clinical disease expression, the avoidance of competitive, high-intensity exercise is considered a reasonable approach, as sympathetic stimulation and high-intensity physical activity play a significant role in arrhythmogenesis and can provoke disease progression.

Question 93

A 23-year-old male presents after being resuscitated from sudden cardiac arrest due to ventricular fibrillation (VF) during a sporting event. Cardiac magnetic resonance imaging reveals fibrofatty myocardial replacement, confirming a diagnosis of arrhythmogenic right ventricular cardiomyopathy. Family screening identifies the condition in his 36-year-old previously asymptomatic male cousin. The cousin now presents to the emergency department reporting hemodynamically stable but persistent palpitations and lightheadedness. Based on the typical age distribution for initial arrhythmic presentations in this disease, what is the most likely etiology of the 36-year-old cousin's symptoms?

• ✓ Sustained monomorphic ventricular tachycardia
• ○ Recurrent ventricular fibrillation
• ○ Complete atrioventricular block
• ○ Atrial fibrillation with rapid ventricular response

Explanation. In arrhythmogenic right ventricular cardiomyopathy, a condition characterized by fibrofatty myocardial replacement, the clinical presentation varies by age. Individuals who present initially with sustained monomorphic ventricular tachycardia are typically older, with a median age of 36 years, whereas those whose first presentation is sudden cardiac death or ventricular fibrillation tend to be younger, with a median age of 23 years.

Question 94

A 19-year-old male is evaluated for recurrent palpitations and presyncope during exertion. An electrocardiogram shows T-wave inversions in leads V1-V3, and a cardiac magnetic resonance imaging study reveals right ventricular akinesia with fibrofatty replacement. He is diagnosed with arrhythmogenic right ventricular cardiomyopathy. Genetic testing reveals compound/digenic mutations in desmosomal genes. What is the clinical implication of this specific genetic finding?

• ✓ It is associated with an increased risk of ventricular arrhythmias at a younger age.
• ○ It is the most common genetic finding, present in up to 73% of probands.
• ○ It indicates a 100% disease penetrance in his first-degree relatives.
• ○ It suggests a more benign clinical course with a significantly lower rate of syncope.

Explanation. Compound or digenic mutations in arrhythmogenic right ventricular cardiomyopathy are associated with an increased risk of ventricular arrhythmias at a younger age.

Question 95

A 22-year-old male recently diagnosed with definite arrhythmogenic right ventricular cardiomyopathy (ARVC) is considered at high risk for ventricular arrhythmias (VA) and is discussing the placement of an implantable cardioverter-defibrillator (ICD). He is concerned about the lifetime risk of device-related complications and asks about the actual life-saving potential of the device. How should the cardiologist counsel the patient regarding the expected nature of appropriate ICD interventions in high-risk ARVC patients?

• ○ Almost all appropriate ICD interventions are triggered by fast ventricular tachycardia (>= 250 beats per minute) or ventricular fibrillation.
• ✓ In approximately 3 out of 4 cases, appropriate ICD therapy treats an arrhythmia that may not be considered acutely life-saving.
• ○ Appropriate ICD interventions in this population are rare, occurring in less than 5% of high-risk patients over a 5-year period.
• ○ Risk prediction models for ARVC are exclusively based on life-threatening arrhythmic endpoints, ensuring every appropriate shock is life-saving.

Explanation. In high-risk ARVC patients, while appropriate ICD therapy is frequently delivered for ventricular arrhythmias, roughly 3 out of 4 of these appropriate interventions treat arrhythmias that are not considered acutely life-saving, as only a minority (16-19%) of cases are triggered by potentially lethal events like fast ventricular tachycardia (>= 250 beats per minute) or ventricular fibrillation.

Question 96

A 28-year-old male presents after a sudden, unprovoked syncopal episode. He had no prodromal symptoms and recovered completely within seconds. His baseline electrocardiogram (ECG) in sinus rhythm shows negative T waves in leads V1-V4 and a terminal QRS duration of 60 ms. Cardiac magnetic resonance imaging confirms right ventricular dysfunction with regional akinesia, consistent with definitive arrhythmogenic right ventricular cardiomyopathy (ARVC). Which of the following is the most appropriate intervention to reduce his risk of sudden cardiac death?

• ✓ Implantation of an implantable cardioverter-defibrillator (ICD)
• ○ Implantation of an implantable loop recorder (ILR)
• ○ Initiation of oral flecainide therapy
• ○ Radiofrequency catheter ablation of the right ventricle

Explanation. Arrhythmic syncope is a strong predictor for subsequent life-threatening arrhythmic events in patients with definitive arrhythmogenic right ventricular cardiomyopathy. Because of this elevated risk, an implantable cardioverter-defibrillator should be considered to provide life-saving therapy for potential fast ventricular tachycardia or ventricular fibrillation episodes.

Question 97

A 45-year-old male with a confirmed diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) is evaluated in the cardiology clinic. He reports feeling well and denies any history of syncope, palpitations, or sustained arrhythmias. An echocardiogram and cardiac magnetic resonance (CMR) imaging are performed for risk stratification. Which of the following findings provides the strongest indication to consider an implantable cardioverter-defibrillator (ICD) in this patient?

• ✓ A right ventricular fractional area change of 14%
• ○ A right ventricular ejection fraction of 38%
• ○ A left ventricular ejection fraction of 42%
• ○ Frequent non-sustained ventricular tachycardia on Holter monitoring

Explanation. An implantable cardioverter-defibrillator (ICD) should be considered in patients with arrhythmogenic right ventricular cardiomyopathy who demonstrate severe right ventricular dysfunction, which is objectively defined as a right ventricular fractional area change of less than 17% or a right ventricular ejection fraction of less than 35%. A fractional area change of 14% clearly falls below this threshold and represents severe dysfunction warranting consideration for device therapy.

Question 98

A 42-year-old male is recently diagnosed with definite arrhythmogenic right ventricular cardiomyopathy (ARVC). He is symptomatic with palpitations, has a right ventricular ejection fraction of 38%, and frequent episodes of non-sustained ventricular tachycardia (NSVT) on ambulatory monitoring. He is referred for placement of an implantable cardioverter-defibrillator (ICD). In planning the device characteristics and programming, which of the following is the most appropriate consideration based on the typical nature of ventricular arrhythmias in this disease?

• ✓ The device should have anti-tachycardia pacing (ATP) capabilities because the vast majority of ventricular arrhythmia episodes are sustained monomorphic ventricular tachycardia that terminate effectively with ATP.
• ○ A subcutaneous ICD (S-ICD) should be avoided because it cannot deliver the high-energy shocks required for the typical polymorphic ventricular tachycardia seen in ARVC.
• ○ The device should be programmed with shock-only therapy because anti-tachycardia pacing is generally ineffective in terminating arrhythmias in ARVC patients.
• ○ A dual-chamber ICD is strictly mandated due to the high incidence of concurrent atrial fibrillation that initiates the ventricular arrhythmias in ARVC.

Explanation. In patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) who receive an implantable cardioverter-defibrillator (ICD), up to 97.4% of all ventricular arrhythmia episodes are sustained monomorphic ventricular tachycardia (SMVT). These episodes have a very high termination rate by anti-tachycardia pacing (ATP), terminating approximately 92% of all episodes independent of the VT cycle length. Therefore, devices with ATP capabilities are strongly supported to painlessly and effectively terminate the arrhythmias in this patient population.

Question 99

A 34-year-old male with a known diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) presents to the clinic with frequent, bothersome palpitations. A 24-hour Holter monitor reveals a high burden of premature ventricular complexes and multiple episodes of non-sustained ventricular tachycardia. He is currently not on any antiarrhythmic therapy. Which of the following is the most appropriate first-line pharmacological therapy to suppress his symptomatic arrhythmias?

• ○ Sotalol
• ○ Amiodarone
• ✓ Metoprolol
• ○ Flecainide

Explanation. Beta-blockers are recommended as the first-line therapy for the suppression of symptomatic ventricular arrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy.

Question 100

A 24-year-old male presents with presyncope and palpitations. Echocardiography demonstrates a maximum left ventricular (LV) wall thickness of 18 mm with no evidence of abnormal loading conditions such as hypertension or valvular disease. Cardiac magnetic resonance (CMR) confirms the diagnosis of hypertrophic cardiomyopathy (HCM). You are counseling the patient regarding the etiology of his disease and the need for familial screening. Which of the following is the most accurate information to provide?

• ✓ The condition typically has an autosomal dominant inheritance, and a sarcomeric gene mutation is identified in 30% to 60% of patients.
• ○ The condition typically has an autosomal recessive inheritance, meaning screening is primarily focused on his siblings.
• ○ Genetic testing should be exclusively performed on his first-degree relatives to establish familial risk, rather than testing him.
• ○ The estimated prevalence of this condition in the adult population is 1 in 10,000, making a genetic mutation highly unlikely.

Explanation. Hypertrophic cardiomyopathy is usually caused by a mutation with an autosomal dominant inheritance pattern. This genetic basis supports cardiac screening in first-degree relatives alongside genetic testing in the index patient. Furthermore, a sarcomeric gene mutation is successfully identified in 30% to 60% of cases, occurring most frequently in patients who are younger at the time of diagnosis or who have a family history of the condition.

Question 101

A 68-year-old woman with a long-standing diagnosis of hypertrophic cardiomyopathy (HCM) presents to the cardiology clinic for a routine evaluation. She reports a recent decline in her exercise tolerance but denies chest pain, palpitations, or syncope. During a discussion about her long-term prognosis, she asks about the most common causes of mortality for patients with her condition at her age. Which of the following is the most likely cause of HCM-related mortality for this patient?

• ○ Sudden cardiac death from a primary ventricular arrhythmia
• ○ Acute myocardial infarction secondary to left ventricular outflow tract (LVOT) obstruction
• ✓ Stroke or heart failure
• ○ Complications related to inappropriate implantable cardioverter-defibrillator therapies

Explanation. In older patients with hypertrophic cardiomyopathy (typically those over the age of 60), mortality is more often related to progressive disease manifestations such as stroke or heart failure.

Question 102

A 27-year-old female with a recent diagnosis of hypertrophic cardiomyopathy (HCM) undergoes risk stratification for primary prevention of sudden cardiac death (SCD). A 48-hour ambulatory electrocardiogram (ECG) reveals three asymptomatic episodes of non-sustained ventricular tachycardia (NSVT), the longest being 8 beats at 160 beats per minute. Which of the following is most accurate regarding the prognostic significance of NSVT in this patient?

• ○ The duration and rate of the NSVT episodes are the most important predictors of her sudden cardiac death risk.
• ✓ The prognostic value of NSVT for sudden cardiac death is more important in this patient because she is under 30 years old.
• ○ The presence of NSVT inversely correlates with her left ventricular wall thickness on echocardiography.
• ○ NSVT is an exceptionally rare finding, occurring in less than 5% of patients with hypertrophic cardiomyopathy on continuous monitoring.

Explanation. In patients with hypertrophic cardiomyopathy, the prognostic value of non-sustained ventricular tachycardia for sudden cardiac death is particularly important in young patients, specifically those under 30 years of age.

Question 103

A 32-year-old male with a recent diagnosis of hypertrophic cardiomyopathy (HCM) comes to the clinic to discuss his risk of sudden cardiac death (SCD). He reports one episode of unexplained syncope 6 months ago. His echocardiogram demonstrates a maximum left ventricular wall thickness of 24 mm and a left atrial diameter of 46 mm. A recent 48-hour Holter monitor showed a brief run of non-sustained ventricular tachycardia. The physician plans to utilize the externally validated HCM Risk-SCD calculator to estimate his 5-year SCD risk. Which of the following variables is directly incorporated into this specific risk stratification model?

• ○ Presence of an apical aneurysm
• ✓ Left atrial size
• ○ Presence of sarcomeric mutations
• ○ Extensive late gadolinium enhancement (>= 15% of left ventricular mass) on cardiac magnetic resonance imaging

Explanation. The 5-year sudden cardiac death (SCD) risk stratification score (HCM Risk-SCD) is based on seven factors: age, left ventricular wall thickness, left atrial size, left ventricular outflow tract gradient, non-sustained ventricular tachycardia, unexplained syncope, and family history of SCD. Apical aneurysm, extensive late gadolinium enhancement, and the presence of sarcomeric mutations are additional risk markers not captured by the model, which should be considered in patients with intermediate or low calculated risk.

Question 104

A 14-year-old boy with hypertrophic cardiomyopathy (HCM) presents for a routine evaluation. His parents are concerned about his risk of sudden cardiac death (SCD), especially given that his paternal uncle died suddenly at age 30 due to HCM. His echocardiogram reveals a maximal left ventricular wall thickness of 25 mm, an enlarged left atrium, and a peak left ventricular outflow tract (LVOT) gradient of 20 mmHg. A 48-hour Holter monitor shows a run of non-sustained ventricular tachycardia (NSVT). The cardiologist calculates his risk of SCD using the validated pediatric risk calculator (HCM Risk-Kids). Which of the following clinical features, despite being a traditional risk factor in adults, is NOT included in this pediatric risk model?

• ✓ Family history of sudden cardiac death
• ○ Maximal left ventricular wall thickness
• ○ Unexplained syncope
• ○ Non-sustained ventricular tachycardia

Explanation. In contrast to adult risk stratification models for hypertrophic cardiomyopathy, the inclusion of age and a family history of sudden cardiac death did not improve the performance of the pediatric risk model (HCM Risk-Kids). Therefore, family history of sudden cardiac death is not included in the calculator, which instead incorporates parameters such as unexplained syncope, maximal left ventricular wall thickness, large left atrial diameter, low LVOT gradient, and non-sustained ventricular tachycardia.

Question 105

A 24-year-old male is referred to the cardiology clinic after cardiac magnetic resonance (CMR) imaging, performed for atypical chest pain, revealed features suggestive of left ventricular non-compaction (LVNC). He is asymptomatic, has a normal left ventricular ejection fraction (LVEF), and has no family history of cardiomyopathy. When counseling this patient regarding his imaging findings and further evaluation, which of the following statements is most accurate?

• ○ Genetic testing should be prioritized because the yield in index patients with LVNC is exceptionally high.
• ✓ The morphological phenotype of non-compaction based on imaging parameters may also appear in an otherwise healthy population.
• ○ LVNC comprises a homogeneous group of diseases, allowing for universally standardized and definitive diagnostic criteria.
• ○ An abnormal blood pressure response to exercise is required to definitively diagnose LVNC.

Explanation. The morphological phenotype of left ventricular non-compaction based on imaging parameters can be seen in a healthy population, which is a crucial consideration when interpreting isolated imaging findings in asymptomatic individuals.

Question 106

A 28-year-old asymptomatic man is evaluated for a family history of cardiomyopathy. Echocardiography and subsequent cardiac magnetic resonance (CMR) imaging confirm the diagnosis of left ventricular non-compaction (LVNC). His left ventricular ejection fraction is preserved at 58%. In assessing this patient's risk for serious cardiac events, including aborted sudden death or the need for advanced heart failure therapies, which of the following findings is most predictive?

• ✓ Detection of focal fibrosis using late gadolinium enhancement (LGE)
• ○ The specific number and extent of prominent trabeculations
• ○ A high ratio of non-compacted to compacted myocardial thickness
• ○ The presence of left ventricular cavity dilatation

Explanation. In patients with left ventricular non-compaction and a preserved ejection fraction, the detection of focal fibrosis using late gadolinium enhancement on cardiac magnetic resonance imaging is strongly associated with an increased risk of serious cardiac events, including aborted death, the need for implantable cardioverter defibrillator therapy, and heart transplantation.

Question 107

A 62-year-old male with a confirmed diagnosis of Fabry disease presents for a comprehensive cardiovascular evaluation. A recent cardiovascular magnetic resonance (CMR) imaging study demonstrates significant left ventricular hypertrophy (LVH) and the presence of late gadolinium enhancement (LGE). Additionally, a 48-hour Holter monitor records multiple asymptomatic runs of non-sustained ventricular tachycardia (NSVT). He has no history of syncope or sustained ventricular arrhythmias. Based on current understanding of sudden cardiac death risk in this condition, which of the following is the most appropriate strategy regarding primary prevention implantable cardioverter-defibrillator (ICD) placement?

• ○ Proceed with primary prevention ICD implantation as the combination of male gender, LVH, LGE, and NSVT constitutes a formal indication.
• ✓ Defer primary prevention ICD implantation as the current data do not provide guidance for primary prevention in this specific patient population.
• ○ Perform an invasive electrophysiology study (EPS) to definitively establish the indication for primary prevention ICD.
• ○ Initiate chronic amiodarone therapy as an alternative to ICD implantation for primary prevention of sudden cardiac death.

Explanation. While higher age, male gender, left ventricular hypertrophy (LVH), late gadolinium enhancement (LGE), and non-sustained ventricular tachycardia (NSVT) have been identified as potential risk factors associated with sudden cardiac death in Fabry disease, the retrospective, observational nature of the available studies and the low absolute number of sudden cardiac death events do not currently allow for specific guidance or routine indication for primary prevention implantable cardioverter-defibrillator (ICD) implantation.

Question 108

A 72-year-old man with known cardiac wild-type transthyretin amyloidosis (ATTRwt) presents to the emergency department after an episode of syncope. Telemetry shows a run of sustained monomorphic ventricular tachycardia (VT) at 190 bpm causing a drop in blood pressure to 70/40 mmHg. He is successfully cardioverted. After stabilization, what is the most appropriate management regarding device therapy for this patient?

• ○ Routine implantation of a primary prevention implantable cardioverter defibrillator (ICD) regardless of symptoms.
• ✓ Implantation of an ICD should be considered after careful discussion of the competing risks of non-arrhythmic and non-cardiac death.
• ○ Implantation of a pacemaker is the only indicated device therapy because electromechanical dissociation is the primary mechanism of death.
• ○ Catheter ablation of the VT substrate is recommended as first-line therapy over ICD implantation.

Explanation. In patients with cardiac amyloidosis who experience haemodynamically not-tolerated ventricular tachycardia, an implantable cardioverter defibrillator (ICD) should be considered. This decision requires a careful discussion of the competing risks of non-arrhythmic death, such as progressive heart failure, electromechanical dissociation, or autonomic dysfunction, and non-cardiac death.

Question 109

A 38-year-old male presents to the clinic with complaints of palpitations and lightheadedness. On physical examination, he demonstrates delayed muscle relaxation after a firm handshake, distal muscle weakness, and early bilateral cataracts. An electrocardiogram (ECG) reveals a PR interval of 250 ms and a QRS duration of 130 ms. He is diagnosed with the most common muscular dystrophy in the adult population. Which of the following best describes the molecular mechanism responsible for this patient's cardiac conduction delays?

• ○ Direct mutation of the SCN5A gene causing a loss of function of the cardiac sodium channel.
• ✓ Mis-splicing of the SCN5A gene due to a trinucleotide repeat expansion in the DMPK gene.
• ○ Frameshift mutation in the dystrophin gene leading to early-onset conduction block.
• ○ Trinucleotide repeat expansion in the SCN5A gene resulting in mis-splicing of the DMPK gene.

Explanation. Myotonic dystrophy is the consequence of a trinucleotide repeat expansion at the end of the DMPK gene. This genetic alteration results in the mis-splicing of the SCN5A transcript, which subsequently causes the characteristic cardiac conduction system delays and arrhythmias seen in this condition.

Question 110

A 38-year-old male with a confirmed diagnosis of myotonic dystrophy presents for a routine cardiac follow-up. He is completely asymptomatic, denying any history of syncope, presyncope, or palpitations. A 12-lead electrocardiogram (ECG) reveals a PR interval of 250 ms and a QRS duration of 140 ms, which represents a sudden and significant prolongation compared to his prior ECG recorded eight months ago. An invasive electrophysiological study is subsequently performed. Which of the following findings during the study necessitates permanent pacemaker implantation in this asymptomatic patient?

• ✓ An HV interval of 74 ms
• ○ An AH interval of 130 ms
• ○ A Wenckebach cycle length of 400 ms
• ○ A corrected sinus node recovery time of 450 ms

Explanation. In patients with myotonic dystrophy who exhibit a sudden increase in PR interval and QRS duration, an invasive electrophysiological evaluation is indicated due to the high association with atrioventricular block and sudden cardiac death. During this evaluation, finding an HV interval of 70 ms or greater should prompt permanent pacemaker implantation, regardless of the absence of clinical symptoms.

Question 111

A 34-year-old male with a genetically confirmed diagnosis of Emery-Dreifuss muscular dystrophy presents for a routine cardiac evaluation. He is asymptomatic and denies any history of syncope, palpitations, or dyspnea. An electrocardiogram (ECG) shows normal sinus rhythm with a PR interval of 160 ms and a QRS duration of 95 ms. Cardiac magnetic resonance (CMR) imaging demonstrates normal left ventricular size and systolic function, but reveals significant late gadolinium enhancement (LGE) in the left ventricular myocardium. Based on these findings, which of the following is the most appropriate next step in management?

• ✓ Implantation of an implantable cardioverter-defibrillator (ICD)
• ○ Implantation of a permanent pacemaker (PPM)
• ○ Insertion of an implantable loop recorder (ILR)
• ○ Observation with repeat cardiac magnetic resonance (CMR) imaging in 12 months

Explanation. In patients with Emery-Dreifuss muscular dystrophy who have significant late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging, implantation of an implantable cardioverter-defibrillator (ICD) should be considered to mitigate the risk of adverse ventricular arrhythmias and sudden cardiac death.

Question 112

A 45-year-old male with a confirmed diagnosis of myotonic dystrophy is evaluated after a sudden, unheralded syncopal episode while sitting at his desk. Cardiac monitoring reveals no acute arrhythmias. Due to the high clinical suspicion that the syncope was caused by a ventricular arrhythmia, an electrophysiological study is performed. During the study, no ventricular arrhythmias are inducible. Which of the following is the most appropriate next step in the management of this patient?

• ✓ Implantation of an implantable cardioverter-defibrillator
• ○ Implantation of a permanent dual-chamber pacemaker
• ○ Discharge with an implantable loop recorder and annual 12-lead electrocardiogram follow-up
• ○ Serial electrophysiological studies every 12 months to reassess inducibility

Explanation. Myotonic dystrophy patients who present with syncope that is clinically suspected to be driven by a ventricular arrhythmia remain at an elevated risk for arrhythmic sudden cardiac death, and placement of an implantable cardioverter-defibrillator is the appropriate intervention to mitigate this risk, even if ventricular arrhythmias cannot be induced during an electrophysiological study.

Question 113

A 68-year-old man with a history of recent surgical aortic valve replacement presents to the emergency department with sustained palpitations and presyncope. His 12-lead electrocardiogram (ECG) reveals a sustained monomorphic wide complex tachycardia. Subsequent electrophysiology study establishes a diagnosis of bundle branch re-entrant ventricular tachycardia (BBR-VT). Which of the following is a recommended intervention for managing this specific arrhythmia?

• ✓ Catheter ablation
• ○ Implantable cardioverter defibrillator alone
• ○ Chronic sotalol therapy
• ○ Atrioventricular node ablation

Explanation. In cardiac conditions such as following an aortic valve replacement, when complicated by bundle branch re-entrant ventricular tachycardia (BBR-VT), catheter ablation is recommended as an effective and targeted therapeutic intervention.

Question 114

A 22-year-old male presents to the emergency department with progressive dyspnea, orthopnea, and chest discomfort over the past 4 days. He reports a severe flu-like illness two weeks prior. Vital signs show a heart rate of 120 bpm and blood pressure of 85/55 mmHg. Laboratory tests show elevated troponin levels. Echocardiography reveals global left ventricular (LV) hypokinesis with an ejection fraction of 30%, and coronary angiography shows no obstructive lesions. Cardiac magnetic resonance (CMR) imaging reveals late gadolinium enhancement and myocardial edema. While non-invasive imaging is highly suggestive of myocarditis, which of the following represents the diagnostic gold standard to definitively confirm the diagnosis?

• ○ Cardiac magnetic resonance (CMR) imaging
• ✓ Endomyocardial biopsy
• ○ Positron emission tomography-computed tomography (PET-CT)
• ○ Peripheral blood viral polymerase chain reaction (PCR)

Explanation. Endomyocardial biopsy is the diagnostic gold standard for myocarditis, allowing for diagnosis through established histological, immunological, and immunohistochemical criteria, as well as polymerase chain reaction (PCR) testing of the tissue to detect viral genomes.

Question 115

A 28-year-old male presents to a rural community hospital with a 3-day history of flu-like symptoms, pleuritic chest pain, and severe dyspnea. His initial electrocardiogram (ECG) shows complete atrioventricular (AV) block with a wide-complex escape rhythm of 35 beats per minute. Echocardiography demonstrates acute biventricular dysfunction with a left ventricular ejection fraction of 30%. High-sensitivity troponin is markedly elevated. Acute myocarditis is highly suspected. What is the most appropriate next step in the management of this patient?

• ✓ Transfer immediately to a specialized center equipped for endomyocardial biopsy and mechanical circulatory support.
• ○ Admit to the local telemetry unit for continuous monitoring and initiate oral beta-blockers and angiotensin-converting enzyme (ACE) inhibitors.
• ○ Insert a permanent dual-chamber pacemaker before considering any further diagnostic workup.
• ○ Discharge with a wearable cardioverter-defibrillator and arrange for outpatient viral polymerase chain reaction (PCR) testing.

Explanation. Patients with suspected or confirmed acute myocarditis who present with life-threatening features, such as complete atrioventricular block, require referral to a specialized center that has the capacity to perform endomyocardial biopsies, utilize mechanical circulatory support devices, perform cardiac catheterization, and manage complex arrhythmias.

Question 116

A 35-year-old male presents to the emergency department with palpitations and lightheadedness. An electrocardiogram (ECG) reveals sustained monomorphic ventricular tachycardia (SMVT) which is successfully cardioverted. He has no significant past medical history. Echocardiography demonstrates a structurally normal heart with a left ventricular ejection fraction of 55%. Coronary angiography is unremarkable. A cardiac magnetic resonance (CMR) imaging study is ordered to evaluate the unclear etiology of his SMVT. Which of the following CMR findings would most strongly raise the suspicion of underlying myocarditis?

• ✓ Subepicardial and/or intramural late gadolinium enhancement
• ○ Transmural late gadolinium enhancement matching a specific coronary artery territory
• ○ Extensive fibrofatty replacement of the right ventricular free wall
• ○ Asymmetrical septal hypertrophy with focal mid-wall late gadolinium enhancement

Explanation. In patients presenting with sustained monomorphic ventricular tachycardia of unclear etiology, underlying myocarditis should be strongly suspected when cardiac magnetic resonance imaging reveals subepicardial and/or intramural abnormal fibrotic myocardial tissue, which is typically visualized as late gadolinium enhancement.

Question 117

A 45-year-old male with a history of chronic myocarditis presents to the emergency department with palpitations and lightheadedness. An electrocardiogram reveals sustained monomorphic ventricular tachycardia (SMVT). He is hemodynamically stable, and the arrhythmia is successfully terminated with an intravenous anti-arrhythmic drug. He is referred to the electrophysiology laboratory for catheter ablation. During mapping, where is the arrhythmogenic substrate for this patient's arrhythmia most likely to be located?

• ✓ Epicardium of the lateral and basal left ventricle
• ○ Endocardium of the apical right ventricle
• ○ Epicardium of the right ventricular outflow tract
• ○ Endocardium of the basal interventricular septum

Explanation. In patients with chronic myocarditis, catheter ablation can be an effective treatment for sustained monomorphic ventricular tachycardia (SMVT), as the arrhythmogenic substrate for these arrhythmias is typically found on the epicardium of the lateral and basal left ventricle.

Question 118

A 38-year-old male presents with recurrent episodes of sustained ventricular tachycardia. Cardiac magnetic resonance imaging reveals predominant right ventricular (RV) involvement with regional wall motion abnormalities and late gadolinium enhancement. The clinical presentation strongly mimics the phenotype of arrhythmogenic right ventricular cardiomyopathy (ARVC). However, given the lack of family history, the clinical team suspects that the patient may actually have isolated cardiac sarcoidosis. Which of the following modalities is specifically useful in aiding the differential diagnosis between isolated cardiac sarcoidosis and ARVC?

• ✓ Cardiac electroanatomical voltage mapping
• ○ Transthoracic echocardiography with global longitudinal strain
• ○ Endomyocardial biopsy of the left ventricular apex
• ○ High-resolution computed tomography of the chest

Explanation. Cardiac electroanatomical voltage mapping is a useful tool that helps in the differential diagnosis between isolated cardiac sarcoidosis and arrhythmogenic right ventricular cardiomyopathy (ARVC) when the disease predominantly affects the right ventricle and mimics the ARVC phenotype.

Question 119

A 48-year-old man with a known history of biopsy-proven pulmonary sarcoidosis presents for cardiovascular risk stratification. He is currently asymptomatic, with no history of syncope or palpitations. An echocardiogram shows a left ventricular ejection fraction (LVEF) of 40%. You are assessing his risk for adverse outcomes, specifically ventricular arrhythmias (VAs). Which of the following is an established independent risk factor for an adverse outcome and an increased risk of VAs in this condition?

• ✓ Presence of right ventricular or left ventricular scarring on cardiac magnetic resonance (CMR) imaging
• ○ Left ventricular ejection fraction of less than 45%
• ○ Development of sustained ventricular tachycardia during the acute inflammatory phase
• ○ Documentation of intermittent first-degree atrioventricular (AV) block

Explanation. In patients with cardiac sarcoidosis, three specific independent factors are associated with an adverse outcome and an increased risk of ventricular arrhythmias: an LVEF <35%, documentation of high-degree AV block, and the presence of right ventricular or left ventricular scarring on cardiac magnetic resonance (CMR) imaging.

Question 120

A 52-year-old male presents with recurrent syncope. His electrocardiogram (ECG) demonstrates complete atrioventricular (AV) block, establishing a clear indication for permanent cardiac pacing. Transthoracic echocardiography reveals a left ventricular ejection fraction (LVEF) of 45%. Cardiac magnetic resonance (CMR) imaging is performed and does not show any significant late gadolinium enhancement (LGE). Regarding the choice of implantable device, which of the following is the most appropriate management strategy?

• ○ Implantation of a standard permanent pacemaker, as an implantable cardioverter-defibrillator (ICD) is contraindicated when LVEF is >35%.
• ✓ Consideration for an implantable cardioverter-defibrillator (ICD) despite the LVEF being >35%.
• ○ Deferral of permanent device implantation until the LVEF falls to ≤35% or significant scar develops on CMR.
• ○ Placement of a temporary pacemaker followed by reassessment of LVEF in 3 months before deciding on permanent device type.

Explanation. The occurrence of ventricular arrhythmias is significantly higher in patients with complete AV block. Therefore, regardless of the left ventricular ejection fraction (LVEF), an implantable cardioverter-defibrillator (ICD) should be considered in patients who have an indication for permanent cardiac pacing.

Question 121

A 48-year-old man with a history of pulmonary and cardiac sarcoidosis presents with recurrent episodes of sustained monomorphic ventricular tachycardia (VT) despite optimal treatment with oral corticosteroids and an antiarrhythmic drug. He is referred for an electrophysiology study and possible catheter ablation. Pre-procedural imaging with cardiac magnetic resonance (CMR) and positron emission tomography (PET) is obtained to characterize his myocardial tissue. Which of the following best describes the most likely imaging characteristics of the arrhythmogenic substrate responsible for his VT?

• ○ A segment demonstrating active, high-grade inflammation on PET with minimal late gadolinium enhancement on CMR.
• ✓ A segment demonstrating scar transmurality on CMR and a lower degree of inflammation on PET.
• ○ An endocardial segment isolated to the apical region showing both dense scar on CMR and intense focal inflammation on PET.
• ○ A myocardial segment showing normal tissue on CMR but diffuse, high-grade inflammation on PET.

Explanation. Most ventricular tachycardias in cardiac sarcoidosis are explained by a scar-related intramural or epicardial substrate, with no evidence that the arrhythmias are directly triggered by active inflammation itself. Consequently, the arrhythmogenic substrate is predominantly located in segments exhibiting scar transmurality on cardiac magnetic resonance imaging and a correspondingly lower degree of active inflammation on positron emission tomography scans.

Question 122

A 48-year-old man from rural Brazil presents to the cardiology clinic with palpitations and mild dyspnea on exertion. An echocardiogram reveals a left ventricular ejection fraction of 42% and an apical aneurysm. Serologic testing confirms infection with Trypanosoma cruzi. Cardiac magnetic resonance imaging with late gadolinium enhancement demonstrates significant myocardial fibrosis. When discussing the patient's prognosis, what should the physician identify as the most common cause of death in patients with this specific cardiomyopathy?

• ○ Refractory cardiogenic shock
• ✓ Sudden cardiac death, primarily due to ventricular fibrillation
• ○ Bradyarrhythmia progressing to asystole
• ○ Thromboembolic stroke

Explanation. Sudden cardiac death, particularly due to ventricular fibrillation, is the most common cause of death in patients with Chagas' cardiomyopathy. The presence of myocardial fibrosis on imaging and clinical risk scores help identify patients at higher risk for this outcome.

Question 123

A 48-year-old male with a history of Chagas' cardiomyopathy presents with recurrent sustained ventricular tachycardia. Medical management with amiodarone has been optimized, but he continues to experience symptomatic episodes. He is referred for catheter ablation. During the procedure, the electrophysiologist should be prepared to target which of the following areas where the arrhythmogenic substrate is most often located in this condition?

• ○ The subendocardial layer of the left ventricle
• ✓ The epicardium
• ○ The endocardial surface of the right ventricular outflow tract
• ○ The mid-myocardial layer of the interventricular septum

Explanation. In patients with Chagas' cardiomyopathy, the arrhythmogenic substrate responsible for ventricular arrhythmias is characteristically located at the epicardium, which is the primary target for successful catheter ablation.

Question 124

A 68-year-old male is evaluated in the cardiology clinic six months after undergoing surgical aortic valve replacement for severe symptomatic aortic stenosis. He has been compliant with optimal guideline-directed medical therapy. A follow-up transthoracic echocardiogram today demonstrates residual severe left ventricular (LV) dysfunction with an ejection fraction of 30%. The patient is currently in New York Heart Association (NYHA) class II and inquiries about his long-term risk for arrhythmias and the potential need for a defibrillator. What is the most appropriate approach to evaluating this patient for an implantable cardioverter defibrillator (ICD)?

• ✓ Proceed with ICD evaluation strictly following the established recommendations for dilated cardiomyopathy (DCM) and hypokinetic non-dilated cardiomyopathy (HNDCM).
• ○ Reassure the patient that surgical valve replacement essentially eliminates the remaining sudden cardiac death risk, requiring only routine clinical monitoring.
• ○ Withhold ICD evaluation, as patients with residual LV dysfunction post-valvular surgery have significantly lower appropriate device therapy rates compared to those with ischaemic cardiomyopathy.
• ○ Defer ICD implantation because the annual risk of sudden cardiac death in patients with prosthetic valves and residual LV dysfunction is negligibly low.

Explanation. Patients with residual left ventricular (LV) dysfunction after valvular surgery who undergo implantable cardioverter defibrillator (ICD) implantation experience appropriate therapy and mortality rates similar to patients with ischaemic or dilated cardiomyopathy. Because of this comparable risk and therapeutic benefit, the evaluation and decision-making for ICD implantation in these post-surgical patients should follow the standard recommendations established for dilated cardiomyopathy (DCM) and hypokinetic non-dilated cardiomyopathy (HNDCM).

Question 125

A 74-year-old male presents to the emergency department with palpitations, presyncope, and a wide complex tachycardia. He has a history of severe aortic stenosis, for which he underwent surgical aortic valve replacement three years ago. An electrocardiogram confirms the diagnosis of sustained monomorphic ventricular tachycardia (SMVT). Following successful direct-current cardioversion to sinus rhythm, the patient is admitted for further management. Based on his history of aortic valve replacement, which of the following is the most appropriate next step in management and the most likely underlying mechanism for his arrhythmia?

• ✓ Programmed electrical stimulation (PES) is indicated due to a high probability of bundle branch re-entry ventricular tachycardia (BBR-VT), which can be cured with catheter ablation.
• ○ Immediate placement of an implantable cardioverter-defibrillator (ICD) is indicated without further electrophysiologic testing due to the high mortality risk.
• ○ Empirical initiation of oral amiodarone is indicated because bundle branch re-entry ventricular tachycardia (BBR-VT) in this setting is usually refractory to catheter ablation.
• ○ Catheter ablation of the right ventricular outflow tract is indicated as it is the most common source of SMVT in patients following aortic valve replacement.

Explanation. In patients who present with sustained monomorphic ventricular tachycardia (SMVT) after undergoing aortic valve replacement, programmed electrical stimulation (PES) is indicated. This is because there is a high probability that the underlying mechanism of the arrhythmia is bundle branch re-entry ventricular tachycardia (BBR-VT), which is a condition that is potentially curable with catheter ablation.

Question 126

A 28-year-old female with a history of recurrent palpitations and a known diagnosis of myxomatous mitral valve prolapse (MVP) is referred for further evaluation. Holter monitoring shows frequent premature ventricular complexes. Given the association between MVP and sudden cardiac death, a late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging is ordered to evaluate for potential arrhythmic substrate. During the review of the LGE-CMR images, which specific anatomical areas should be most carefully scrutinized for myocardial fibrosis, as they are classically affected by mechanical stretch from excessive mitral valve mobility and systolic curling in this condition?

• ○ Antero-septal left ventricular wall and right ventricular apex
• ✓ Infero-basal left ventricular (LV) free wall and papillary muscles
• ○ Subendocardial layers of the apical left ventricular segments
• ○ Right ventricular free wall and the tricuspid annulus

Explanation. The potential arrhythmic substrate in mitral valve prolapse involves myocardial fibrosis affecting both the infero-basal left ventricular free wall and the papillary muscles. This scarring process is related to mechanical stretch secondary to the excessive mobility of the mitral valve apparatus due to mitral valvular disjunction and posterior systolic curling.

Question 127

A 32-year-old woman presents to the cardiology clinic complaining of intermittent palpitations. Echocardiography demonstrates mitral valve prolapse (MVP) with bi-leaflet involvement and mitral annular disjunction. A 24-hour Holter monitor shows frequent premature ventricular complexes (PVCs) and a brief episode of non-sustained polymorphic ventricular tachycardia. You suspect 'arrhythmic MVP syndrome', which is associated with an increased risk for sudden cardiac death (SCD). Which of the following additional electrocardiographic (ECG) findings is an established proposed criterion for this high-risk phenotype?

• ✓ Negative T-waves in the inferior leads
• ○ T-wave inversions in leads V1 to V3
• ○ Shortened QTc interval
• ○ J-point elevation in leads I and aVL

Explanation. Proposed criteria for an 'arrhythmic MVP syndrome' that are associated with an increased risk for sudden cardiac death include QTc prolongation and/or negative T-waves in the inferior ECG leads, along with features such as young female demographic, mitral annular disjunction, bi-leaflet involvement, and frequent PVCs or non-sustained ventricular tachycardia.

Question 128

A 32-year-old female with a history of surgically repaired congenital heart disease (CHD) in infancy presents to the adult cardiology clinic for a routine evaluation. She is currently asymptomatic and has a normal exercise tolerance. While discussing her long-term prognosis, she inquires about the most significant risks to her survival. With advancements in early management reducing mortality from peri-operative events and early heart failure, sudden cardiac death (SCD) has emerged as a leading cause of mortality in adults with repaired CHD. Which of the following best describes the primary pathophysiological substrate for the ventricular arrhythmias (VAs) that lead to SCD in this population?

• ✓ The combination of surgical incisions, myocardial scar, and residual or new anatomical abnormalities.
• ○ Accelerated coronary atherosclerosis secondary to abnormal pediatric hemodynamics.
• ○ Age-related fibrotic degeneration of the atrioventricular node and bundle branches.
• ○ Chronic hypoxic damage to the His-Purkinje system occurring prior to surgical correction.

Explanation. In adults who have survived into adulthood following surgical repair of congenital heart disease, the substrate for ventricular arrhythmias is primarily formed by the combination of surgical incisions, myocardial scar tissue, and any residual or newly developed anatomical abnormalities. This structural remodeling and scarring create the necessary pathophysiological conditions for arrhythmogenesis, which directly contributes to sudden cardiac death becoming a leading cause of mortality in this demographic.

Question 129

A 30-year-old female with a history of surgically repaired congenital heart disease (CHD) presents to the cardiology clinic reporting recent episodes of unexplained syncope and severe palpitations. A 24-hour Holter monitor demonstrates multiple runs of non-sustained ventricular tachycardia (NSVT). A transthoracic echocardiogram reveals biventricular physiology with a systemic left ventricle and an ejection fraction of 48%. Which of the following is the most appropriate next step in the evaluation and risk stratification of this patient?

• ○ Immediate implantable cardioverter-defibrillator (ICD) implantation
• ✓ Programmed electrical stimulation (PES)
• ○ Transesophageal echocardiography (TEE)
• ○ Pre-operative catheter mapping and ablation

Explanation. In patients with congenital heart disease who present with unexplained syncope, severe arrhythmia symptoms (such as palpitations or pre-syncope), and non-sustained ventricular tachycardia (NSVT), programmed electrical stimulation (PES) should be considered to aid in further risk stratification for sudden cardiac death.

Question 130

A 32-year-old woman with congenital heart disease (CHD) and an unrepaired intracardiac shunt is resuscitated from an out-of-hospital cardiac arrest due to sustained ventricular fibrillation. Comprehensive evaluation, including cardiac magnetic resonance and hemodynamic assessment, reveals no identifiable reversible factors or new anatomical abnormalities requiring surgical intervention. She has normal sinus node function and does not require anti-tachycardia pacing. Which of the following devices is the most appropriate choice for secondary prevention of sudden cardiac death (SCD) in this patient?

• ✓ Subcutaneous implantable cardioverter-defibrillator (ICD)
• ○ Transvenous single-chamber ICD
• ○ Transvenous dual-chamber ICD
• ○ Cardiac resynchronization therapy defibrillator (CRT-D)

Explanation. In patients with congenital heart disease and an intracardiac shunt who lack identifiable reversible factors for their arrhythmia, a subcutaneous implantable cardioverter-defibrillator is an indicated alternative for secondary prevention of sudden cardiac death, particularly when anti-tachycardia and anti-bradycardia pacing are not required.

Question 131

A 31-year-old female with a history of surgically repaired transposition of the great arteries presents to the adult congenital heart disease clinic for a routine evaluation. She reports being able to perform her daily activities without difficulty and denies any recent palpitations or syncope. Her echocardiogram shows preserved ventricular function and mild atrioventricular valve regurgitation. An electrocardiogram (ECG) reveals sinus rhythm. Which of the following ECG findings is considered a lesion-specific risk factor for sudden cardiac death in this patient?

• ✓ QRS duration of 145 ms
• ○ Incomplete right bundle branch block with a QRS duration of 110 ms
• ○ Heart rate of 95 beats per minute
• ○ PR interval of 210 ms

Explanation. In patients with transposition of the great arteries, a wide QRS duration of 140 ms or greater is specifically recognized as a lesion-specific risk factor for sudden cardiac death.

Question 132

A 42-year-old male with a history of idiopathic ventricular fibrillation (VF) and an implantable cardioverter-defibrillator (ICD) presents to the emergency department after receiving 6 ICD shocks in the past 24 hours. Telemetry shows recurrent VF episodes triggered by identical premature ventricular complexes (PVCs). Despite initiation of intravenous antiarrhythmic therapy, the patient continues to experience frequent PVCs and recurrent VF. He is referred for catheter ablation. During the electrophysiology study, mapping is performed to identify the source of the triggering PVCs. Which of the following is the most likely anatomic origin of the PVCs triggering the recurrent VF episodes in this patient?

• ✓ Purkinje system
• ○ Right ventricular outflow tract
• ○ Left ventricular summit
• ○ Aortic sinus of Valsalva

Explanation. In patients with recurrent episodes of ventricular fibrillation triggered by a similar premature ventricular complex unresponsive to medical treatment, the triggering premature ventricular complexes most commonly originate from the Purkinje system and can be targeted for catheter ablation with a high acute success rate.

Question 133

A 32-year-old male presents after surviving a sudden cardiac arrest (SCA). Rhythm strips from emergency medical services show ventricular fibrillation (VF). Extensive workup, including blood chemistry, high-lead electrocardiogram (ECG), echocardiogram, coronary angiography, exercise stress testing, sodium-channel blocker testing, and cardiovascular magnetic resonance (CMR) imaging, reveals no structural, channelopathic, metabolic, or toxicological etiology. A diagnosis of idiopathic ventricular fibrillation (IVF) is established. The patient's 30-year-old brother inquires about clinical evaluation for himself and other first-degree relatives. Which of the following is the most accurate statement regarding the evaluation of this patient's family?

• ○ Genetic testing of the proband has a diagnostic yield of greater than 50% and is the definitive method to guide family screening.
• ○ Clinical evaluation of first-degree family members has a high diagnostic yield for identifying occult structural heart disease.
• ✓ The clinical significance of detecting an early repolarization pattern (ERP) in asymptomatic relatives is uncertain.
• ○ First-degree relatives should be primarily screened using sodium-channel blocker testing to confirm a shared channelopathy.

Explanation. In cases of idiopathic ventricular fibrillation, clinical evaluation of first-degree family members may be considered, but the overall diagnostic yield is low. Furthermore, when an early repolarization pattern is incidentally detected in these asymptomatic relatives, its significance and associated clinical risk remain uncertain.

Question 134

A 14-year-old female is evaluated in the cardiology clinic after a screening electrocardiogram (ECG) reveals a markedly prolonged QT interval. She is diagnosed with Long QT syndrome (LQTS) and is currently completely asymptomatic. Her 16-year-old brother, who also has LQTS, recently experienced an episode of syncope during a soccer game. Neither sibling is currently receiving treatment. What is the estimated annual rate of sudden cardiac death (SCD) in the untreated asymptomatic female compared to her untreated sibling with a history of syncope?

• ✓ Asymptomatic: less than 0.5%; Syncope: approximately 5%
• ○ Asymptomatic: approximately 2%; Syncope: approximately 10%
• ○ Asymptomatic: less than 1%; Syncope: approximately 15%
• ○ Asymptomatic: approximately 5%; Syncope: approximately 20%

Explanation. In patients with Long QT Syndrome (LQTS), the annual rate of sudden cardiac death in asymptomatic, untreated individuals is estimated to be less than 0.5%, whereas this rate increases to around 5% in those who have a history of syncope.

Question 135

A 4-year-old boy is brought to the pediatric cardiology clinic for evaluation of recurrent syncope. His 12-lead electrocardiogram (ECG) shows a markedly prolonged QT interval. Physical examination reveals syndactyly and facial dysmorphism. His parents mention he has recently been diagnosed with autism spectrum disorder. Based on this clinical presentation, what is the expected inheritance pattern and specific subtype of this patient's syndrome?

• ✓ Autosomal-dominant inheritance; Timothy Syndrome (LQT8)
• ○ Autosomal-recessive inheritance; Timothy Syndrome (LQT8)
• ○ Autosomal-recessive inheritance; Jervell and Lange-Nielsen Syndrome
• ○ Autosomal-dominant inheritance; Andersen-Tawil Syndrome (LQT7)

Explanation. The clinical presentation of a prolonged QT interval accompanied by syndactyly, autism spectrum disorder, and facial dysmorphism is characteristic of Timothy Syndrome (LQT8), which follows an autosomal-dominant pattern of inheritance.

Question 136

A 19-year-old male is evaluated in the cardiology clinic after an episode of sudden, unprovoked syncope occurring while walking up a flight of stairs, highly suspicious for an arrhythmic etiology. His baseline 12-lead electrocardiogram (ECG) reveals normal sinus rhythm, a normal QRS duration, and a corrected QT (QTc) interval of 468 ms. His metabolic panel and echocardiogram are unremarkable. Which of the following statements regarding the diagnosis of Long QT Syndrome (LQTS) in this patient is accurate?

• ○ An epinephrine challenge is recommended as the next routine diagnostic step to confirm the diagnosis.
• ○ A diagnosis of LQTS cannot be considered until his QTc interval measures at least 480 ms on repeated resting electrocardiograms.
• ✓ His QTc interval of 460 ms or greater in the setting of arrhythmic syncope is sufficient to consider a diagnosis of LQTS.
• ○ Measurement of the QT interval must be adjusted by his QRS duration using a specific formula before considering the diagnosis.

Explanation. In patients presenting with arrhythmic syncope or cardiac arrest, a corrected QT (QTc) interval of 460 ms or greater on a baseline electrocardiogram is sufficient to consider a clinical diagnosis of Long QT Syndrome (LQTS).

Question 137

A 28-year-old male is evaluated in the cardiology clinic following an episode of syncope while asleep. An electrocardiogram (ECG) reveals a markedly prolonged corrected QT (QTc) interval of 520 ms. Genetic testing confirms the diagnosis of Long QT Syndrome type 3 (LQT3) with a pathogenic mutation in the SCN5A gene. The patient is currently taking nadolol. The managing cardiologist is considering adding mexiletine to reduce his arrhythmic risk. Which of the following is the most appropriate approach to initiating mexiletine in this patient?

• ✓ Perform an oral test dose to verify that the QTc shortens by at least 40 ms before prescribing chronic treatment.
• ○ Initiate chronic mexiletine therapy immediately because it is a universally effective genotype-specific therapy for all SCN5A mutations.
• ○ Discontinue nadolol prior to starting mexiletine because beta-blockers are entirely contraindicated in LQT3.
• ○ Switch nadolol to a selective beta-1 blocker before initiating chronic mexiletine therapy.

Explanation. Because different mutations in the SCN5A gene show variable responses to mexiletine, it is advisable to perform an oral testing challenge prior to initiating long-term therapy. Verifying that the corrected QT (QTc) interval shortens by at least 40 milliseconds confirms that the specific mutation is responsive, justifying the chronic prescription of the medication to effectively reduce arrhythmic risk.

Question 138

A 19-year-old male with a known diagnosis of long QT syndrome (LQTS) is brought to the emergency department after experiencing a syncopal episode while walking up a flight of stairs. He has been highly compliant with his prescribed beta-blocker therapy, which is currently at the optimal and maximally tolerated dose. His 12-lead electrocardiogram (ECG) reveals a sinus rhythm with a QTc of 510 ms. Which of the following is the most appropriate next step in the long-term management of this patient?

• ✓ Proceed with implantable cardioverter-defibrillator (ICD) implantation.
• ○ Add flecainide to his current pharmacological regimen.
• ○ Switch his beta-blocker to oral mexiletine.
• ○ Reassure the patient and maintain the current dose of his beta-blocker.

Explanation. Implantable cardioverter-defibrillator (ICD) implantation is indicated for patients with long QT syndrome who experience syncope despite optimal pharmacological therapy, as these syncopal events are associated with an increased risk of cardiac arrest.

Question 139

A 22-year-old female with known Long QT syndrome (LQTS) presents to the clinic. She underwent implantable cardioverter-defibrillator (ICD) placement two years ago after an aborted sudden cardiac arrest. She is currently adherent to maximally tolerated doses of nadolol. Over the past month, she has experienced three appropriate ICD shocks for torsades de pointes. Her laboratory tests show normal serum potassium and magnesium levels, and she strictly avoids all genotype-specific triggers and QT-prolonging medications. Which of the following is the most appropriate next step in the management of this patient?

• ✓ Refer the patient for left cardiac sympathetic denervation
• ○ Perform programmed electrical stimulation to risk-stratify for further events
• ○ Switch nadolol to a selective beta-blocker such as metoprolol
• ○ Perform an epinephrine challenge test to assess the arrhythmogenic mechanism

Explanation. Left cardiac sympathetic denervation is recommended for patients who already have an implantable cardioverter-defibrillator (ICD) but continue to experience multiple shocks despite optimal medical therapy with beta-blockers. The procedure is safe, effective, well-tolerated, and reduces the burden of arrhythmic events without having a negative impact on cardiovascular performance.

Question 140

A 28-year-old male with a known diagnosis of Long QT syndrome type 3 (LQT3) and an implantable cardioverter-defibrillator (ICD) presents for follow-up. He is currently maintained on maximally tolerated doses of nadolol and mexiletine. Over the past month, he has experienced three episodes of syncope, and his device interrogation confirms multiple appropriate shocks for recurrent ventricular arrhythmias. What is the most appropriate next step in the management of this patient?

• ✓ Left cardiac sympathetic denervation (LCSD)
• ○ Invasive electrophysiologic study
• ○ Radiofrequency ablation of the ventricular arrhythmia substrate
• ○ Discontinue mexiletine and initiate amiodarone therapy

Explanation. Left cardiac sympathetic denervation (LCSD) is indicated in patients with symptomatic Long QT syndrome (LQTS) who continue to experience multiple shocks or syncope due to ventricular arrhythmias despite having an implantable cardioverter-defibrillator (ICD) and receiving optimal medical therapy, including beta-blockers and genotype-specific drugs (such as mexiletine for LQT3).

Question 141

A 28-year-old male is evaluated in the cardiology clinic following a recent episode of syncope that occurred while he was sleeping. An electrocardiogram (ECG) reveals a markedly prolonged QTc interval of 520 ms. Subsequent genetic testing identifies a pathogenic mutation in the SCN5A gene, confirming the diagnosis of Long QT Syndrome type 3 (LQT3). Which of the following medications is specifically indicated as a targeted therapy for this patient's condition?

• ✓ Mexiletine
• ○ Sotalol
• ○ Amiodarone
• ○ Flecainide

Explanation. Mexiletine is specifically indicated as a targeted medical therapy for patients with Long QT Syndrome type 3 (LQT3) who carry a pathogenic SCN5A mutation.

Question 142

A 24-year-old female is evaluated for palpitations and episodic muscle weakness. Physical examination reveals micrognathia and clinodactyly. An electrocardiogram (ECG) demonstrates prominent U waves without significant QT prolongation. Telemetry captures frequent runs of non-sustained bidirectional ventricular tachycardia (VT). She remains hemodynamically stable during these episodes and denies any history of syncope. Genetic testing reveals a loss-of-function mutation in the KCNJ2 gene, confirming a diagnosis of Andersen-Tawil syndrome Type 1. To reduce her ventricular arrhythmia burden, which of the following medication strategies is most appropriate?

• ○ Initiation of amiodarone
• ✓ Initiation of flecainide and/or a beta-blocker
• ○ Initiation of verapamil
• ○ Implantation of an implantable cardioverter-defibrillator (ICD) followed by amiodarone

Explanation. In patients with Andersen-Tawil syndrome (LQT7), the clinical manifestations typically include ventricular arrhythmias such as bidirectional ventricular tachycardia, dysmorphologies, and periodic paralysis caused by a KCNJ2 loss-of-function mutation. For the medical management of these ventricular arrhythmias in a hemodynamically stable patient, flecainide and/or beta-blockers are the appropriate pharmacological agents as they effectively reduce the arrhythmia burden.

Question 143

A 28-year-old male undergoes an electrophysiology evaluation for recurrent palpitations. His baseline electrocardiogram (ECG) is normal. During the study, he is administered a sodium channel-blocking drug, which unexpectedly induces a type 1 Brugada ECG pattern (J point elevation >2 mV with coved ST elevation and T wave inversion in lead V1). He has no history of syncope, no documented polymorphic ventricular tachycardia (PVT) or ventricular fibrillation (VF), and no family history of sudden cardiac death or Brugada syndrome (BrS). Structural heart disease has been comprehensively ruled out. What is the most appropriate conclusion regarding a diagnosis of BrS in this patient?

• ✓ He does not meet the diagnostic criteria for Brugada syndrome.
• ○ He is diagnosed with Brugada syndrome based on the induced type 1 ECG pattern.
• ○ He is diagnosed with Brugada syndrome because palpitations are considered an equivalent clinical feature.
• ○ He does not meet the criteria for Brugada syndrome unless the pattern is also induced by fever.

Explanation. An induced type 1 Brugada electrocardiogram pattern requires the presence of additional clinical features, such as documented polymorphic ventricular tachycardia or ventricular fibrillation, arrhythmic syncope, or a relevant family history, to establish a definitive diagnosis of Brugada syndrome.

Question 144

A 32-year-old man presents to the cardiology clinic after a sudden episode of syncope while watching television. He reports no preceding nausea, diaphoresis, or warning signs. A 12-lead electrocardiogram (ECG) reveals a spontaneous type 1 coved ST-segment elevation in leads V1 and V2, and he is diagnosed with Brugada syndrome (BrS). He has no prior history of cardiac arrest. The patient is anxious and asks about his prognosis, potential triggers, and the utility of genetic testing. Which of the following is correct regarding his condition?

• ✓ His presentation with unexplained syncope confers an arrhythmic event risk that is approximately four times higher than that of an asymptomatic patient with Brugada syndrome.
• ○ Genetic testing is highly likely to pinpoint the etiology, as pathogenic variants—most commonly in the SCN5A gene—are found in over 80% of patients with Brugada syndrome.
• ○ He should be counseled that excessive alcohol intake and fever are generally safe, whereas strenuous exercise is the primary trigger for ventricular fibrillation in this syndrome.
• ○ Implantation of an implantable loop recorder (ILR) is generally discouraged in this scenario, as it rarely changes clinical management for patients with unexplained syncope.

Explanation. Patients with Brugada syndrome who present with unexplained syncope have an elevated prognostic risk, experiencing future arrhythmic events at a rate that is four times higher than that of entirely asymptomatic patients.

Question 145

A 42-year-old male is evaluated in the cardiology clinic. He is completely asymptomatic, exercises regularly, and has no family history of sudden cardiac death. A screening Electrocardiogram (ECG) reveals a coved ST-segment elevation of 2.5 mm in leads V1 and V2, characteristic of a spontaneous type 1 Brugada pattern. The cardiologist is discussing the possibility of performing an electrophysiological study (EPS) for risk stratification. Regarding the use of EPS in asymptomatic Brugada syndrome (BrS) patients, which of the following statements is most accurate?

• ✓ Induction of a sustained ventricular arrhythmia (VA) during EPS provides a potentially clinically actionable result specifically because the patient has a spontaneous type 1 ECG pattern.
• ○ Induction of a sustained VA during EPS provides a clinically actionable result in all asymptomatic patients with BrS, regardless of their baseline ECG pattern.
• ○ EPS is primarily indicated to unmask a type 1 ECG pattern in this patient, as spontaneous patterns carry a low risk of future VA.
• ○ The utility of EPS in providing actionable risk stratification is highest in asymptomatic patients who lack both spontaneous type 1 patterns and QRS fragmentation.

Explanation. The induction of sustained ventricular arrhythmias during electrophysiological studies is associated with a potentially clinically actionable result specifically in the subset of asymptomatic patients who demonstrate a spontaneous type 1 Brugada pattern on their baseline Electrocardiogram.

Question 146

A 38-year-old male with a history of Brugada syndrome and an implantable cardioverter-defibrillator (ICD) is admitted to the cardiac intensive care unit for electrical storm, having received multiple appropriate shocks for recurrent ventricular fibrillation (VF). Following initial stabilization with an intravenous isoproterenol infusion, the electrophysiology team plans to perform a catheter ablation to suppress further VF episodes and normalize his electrocardiogram (ECG). Which of the following anatomical locations is the primary target for substrate modification in this condition?

• ✓ Epicardial right ventricular outflow tract (RVOT)
• ○ Endocardial right ventricular outflow tract (RVOT)
• ○ Epicardial left ventricular apex
• ○ Endocardial left ventricular outflow tract (LVOT)

Explanation. An abnormal fibrotic arrhythmogenic substrate located in the epicardial right ventricular outflow tract (RVOT) is responsible for the ST-segment elevation in the right precordial leads and the occurrence of ventricular fibrillation in patients with Brugada syndrome. Ablation targeting these specific abnormal epicardial areas can markedly suppress recurrent ventricular fibrillation and normalize the electrocardiogram.

Question 147

A 32-year-old male with no prior medical history is resuscitated from an out-of-hospital cardiac arrest due to ventricular fibrillation (VF). Comprehensive imaging, including echocardiography and coronary angiography, demonstrates no structural heart disease. His post-resuscitation 12-lead electrocardiogram (ECG) reveals an early repolarization pattern (ERP) in the inferior leads. Which of the following findings most strongly supports a high-risk early repolarization syndrome (ERS) phenotype in this patient?

• ✓ J-waves associated with a horizontal or descending ST-segment
• ○ A persistent, static J-point elevation without dynamic changes
• ○ Prominent J-waves measuring exactly 1.5 mm in amplitude
• ○ Identification of a pathogenic variant on an inherited arrhythmia genetic panel

Explanation. High-risk electrocardiogram features that increase the likelihood of early repolarization syndrome include prominent J-waves ≥2 mm, dynamic changes in J-point elevation (>0.1 mV), and J-waves associated with a horizontal or descending ST-segment.

Question 148

A 38-year-old male with early repolarization syndrome and a previously placed implantable cardioverter-defibrillator (ICD) presents to the emergency department experiencing an electrical storm. Device interrogation confirms recurrent episodes of ventricular fibrillation (VF) appropriately treated with shocks. Despite initial stabilization, he continues to have frequent premature ventricular complexes and short runs of non-sustained VF. Which of the following intravenous infusions is most effective for the acute suppression of recurrent ICD discharges in this patient?

• ✓ Isoproterenol
• ○ Amiodarone
• ○ Lidocaine
• ○ Magnesium sulfate

Explanation. Isoproterenol infusion is effective in the acute suppression of recurrent implantable cardioverter-defibrillator discharges and electrical storm.

Question 149

A 15-year-old male presents for evaluation after experiencing syncope while running a race. His resting electrocardiogram (ECG) and echocardiogram are unremarkable, showing no evidence of structural heart disease or ischemia. During a treadmill exercise stress test, he develops bidirectional ventricular tachycardia. Family history is notable for his father having a history of similar exercise-induced arrhythmias, indicating an autosomal dominant pattern of inheritance. Which of the following genetic mutations is most likely responsible for this patient's presentation?

• ✓ A mutation in the gene encoding for the cardiac ryanodine receptor (RYR2)
• ○ A mutation in the cardiac calsequestrin gene (CASQ2)
• ○ A mutation in the KCNJ2 gene
• ○ A mutation in the TRDN gene

Explanation. Catecholaminergic polymorphic ventricular tachycardia is a heritable disorder characterized by catecholamine-induced bidirectional ventricular tachycardia in the absence of structural heart disease or ischemia. The autosomal dominant form of this condition, consistent with the transmission from the patient's father, is due to mutations in the gene encoding for the cardiac ryanodine receptor (RYR2).

Question 150

A 9-year-old boy presents to the clinic for evaluation of a syncopal episode that occurred while playing soccer. His baseline 12-lead electrocardiogram (ECG) reveals sinus bradycardia and prominent U waves, and his echocardiogram is structurally normal. An exercise stress test is performed, which elicits bidirectional ventricular tachycardia, establishing the diagnosis of catecholaminergic polymorphic ventricular tachycardia (CPVT). Which of the following is the most appropriate approach to the management of this patient and his relatives?

• ○ Initiate therapy with a selective beta-blocker such as metoprolol as the preferred first-line agent.
• ✓ Prescribe a non-selective beta-blocker without intrinsic sympathomimetic activity, such as nadolol, as first-line therapy.
• ○ Withhold prophylactic beta-blocker therapy in genetically positive asymptomatic family members until stress-induced arrhythmias are documented.
• ○ Perform an isoproterenol challenge to determine the required dosage of pharmacological therapy.

Explanation. Exercise restriction and beta-blockers without intrinsic sympathomimetic activity are the first-line therapy for patients with catecholaminergic polymorphic ventricular tachycardia (CPVT). Non-selective beta-blockers such as nadolol and propranolol are specifically preferred for pharmacological management.

Question 151

A 16-year-old male with a history of catecholaminergic polymorphic ventricular tachycardia (CPVT) presents after surviving a sudden cardiac arrest during a soccer match. He is started on maximal pharmacological protection with a beta-blocker and flecainide, and an implantable cardioverter-defibrillator (ICD) is placed. Which of the following describes the most appropriate programming strategy for his device?

• ✓ Program with long detection delays and high rate cutoffs before delivering defibrillation therapy.
• ○ Program with short detection delays and low rate cutoffs to rapidly terminate bidirectional ventricular tachycardia.
• ○ Program standard rate cutoffs with short detection delays to prevent progression to ventricular fibrillation.
• ○ Program the device with standard shock protocols as bidirectional ventricular tachycardia responds highly effectively to early defibrillation.

Explanation. In patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), an implantable cardioverter-defibrillator (ICD) should be programmed with long delays and high rates before defibrillation. This strategy is necessary because the initiating bidirectional ventricular tachycardia responds less effectively to defibrillation than subsequent polymorphic ventricular tachycardia or ventricular fibrillation, and painful shocks can trigger further catecholamine release, leading to incessant arrhythmias.

Question 152

A 12-year-old boy with catecholaminergic polymorphic ventricular tachycardia (CPVT) presents for a routine follow-up. He is currently maintained on the highest tolerated dose of nadolol (a beta-blocker) and adheres to strict exercise restriction. During an exercise stress test performed in the clinic, he is noted to have persistent exertional premature ventricular complexes (PVCs) and a brief run of bidirectional ventricular tachycardia. What is the most appropriate next step in his management?

• ○ Refer the patient for left cardiac sympathetic denervation (LCSD).
• ✓ Add flecainide to his current medical regimen.
• ○ Proceed with implantable cardioverter-defibrillator (ICD) placement.
• ○ Perform programmed electrical stimulation (PES) to stratify the risk of sudden cardiac death.

Explanation. The addition of flecainide is indicated for patients with catecholaminergic polymorphic ventricular tachycardia who continue to experience persistent exertional premature ventricular complexes, polymorphic or bidirectional ventricular tachycardia, or recurrent syncope despite therapy with beta-blockers.

Question 153

A 24-year-old male presents to the emergency department after a syncopal episode while resting. An electrocardiogram (ECG) reveals a markedly short QTc interval of 310 ms. Echocardiography demonstrates a structurally normal heart with normal ejection fraction and no valvular abnormalities. The patient is subsequently diagnosed with Short QT syndrome (SQTS), predisposing him to premature atrial fibrillation (AF) and ventricular fibrillation (VF). Which of the following genetic mechanisms is associated with this patient's condition?

• ✓ Gain of function mutations in KCNH2 or KCNQ1
• ○ Loss of function mutations in KCNH2 or KCNQ1
• ○ Gain of function mutations in RYR2
• ○ Loss of function mutations in MYBPC3

Explanation. Short QT syndrome (SQTS) is a genetic disorder characterized by a short QT interval, premature atrial fibrillation, and ventricular fibrillation in the context of a structurally normal heart, and it is characteristically associated with gain of function mutations in the KCNH2 and KCNQ1 genes.

Question 154

A 29-year-old male with a history of an aborted cardiac arrest and a known diagnosis of Short QT Syndrome (SQTS) is brought to the emergency department after receiving five appropriate implantable cardioverter-defibrillator (ICD) shocks within the last two hours. Telemetry confirms recurrent episodes of sustained ventricular tachycardia consistent with an electrical storm. His baseline electrocardiogram (ECG) previously demonstrated a corrected QT interval (QTc) of 310 ms. Which of the following medications is most appropriate to consider for the acute management of this patient's electrical storm?

• ○ Amiodarone
• ✓ Isoprenaline
• ○ Quinidine
• ○ Nicorandil

Explanation. Isoprenaline is an appropriate pharmacological therapy to consider for the acute management of electrical storm in patients with Short QT Syndrome.

Question 155

A 32-year-old male presents for evaluation following a sudden syncopal episode that occurred while he was watching television. The syncope was unprovoked, and he recovered consciousness rapidly. His 12-lead electrocardiogram (ECG) demonstrates a corrected QT (QTc) interval of 340 ms. Transthoracic echocardiogram shows normal biventricular size and function with no structural abnormalities. Genetic testing reveals a pathogenic mutation associated with short QT syndrome (SQTS). Which of the following is the most appropriate next step in management for this patient?

• ✓ Implantable cardioverter defibrillator (ICD) placement
• ○ Initiation of oral quinidine therapy
• ○ Implantation of an implantable loop recorder (ILR)
• ○ Initiation of oral beta-blocker therapy

Explanation. Implantable cardioverter defibrillator (ICD) implantation should be considered in patients diagnosed with short QT syndrome (SQTS) who have experienced an episode of arrhythmic syncope.

Question 156

A 32-year-old woman, G1P0, presents to the emergency department at 36 weeks of gestation with palpitations and lightheadedness. An electrocardiogram reveals new-onset monomorphic ventricular tachycardia. Her vital signs are stable, and the arrhythmia is successfully terminated. She has no prior history of structural heart disease or arrhythmias. Following acute management, which of the following conditions is most critical to rule out based on the timing of her presentation?

• ○ Arrhythmogenic right ventricular cardiomyopathy
• ✓ Peri-partum cardiomyopathy
• ○ Congenital long QT syndrome
• ○ Hypertrophic cardiomyopathy

Explanation. Peri-partum cardiomyopathy must be ruled out in patients who present with new-onset ventricular tachycardia during the last 6 weeks of pregnancy or in the early post-partum period.

Question 157

A 34-year-old woman is diagnosed with peripartum cardiomyopathy (PPCM) at 37 weeks of gestation. An echocardiogram reveals a left ventricular ejection fraction (LVEF) of 28%. She is initiated on appropriate medical therapy for heart failure. Given her severely reduced LVEF, you are evaluating strategies to prevent sudden cardiac death (SCD). Which of the following is the most appropriate approach for SCD prevention in this patient?

• ○ Proceed with early implantation of an implantable cardioverter-defibrillator (ICD) utilizing echocardiographic guidance.
• ✓ Prescribe a wearable cardioverter-defibrillator (WCD) for the first 3-6 months.
• ○ Schedule an electrophysiology study immediately postpartum to determine the need for an ICD.
• ○ Initiate prophylactic amiodarone therapy to suppress ventricular arrhythmias until ventricular recovery occurs.

Explanation. In patients with peripartum cardiomyopathy (PPCM), thresholds for early implantable cardioverter-defibrillator (ICD) implantation are higher than in other conditions due to a high rate of spontaneous recovery of ventricular function after delivery. A wearable cardioverter-defibrillator (WCD) is utilized to temporarily prevent sudden cardiac death during the first 3-6 months after the diagnosis of PPCM in patients with an LVEF <35%, while awaiting potential recovery.

Question 158

A 32-year-old woman, primigravida at 16 weeks gestation, presents with recurrent episodes of symptomatic palpitations. An electrocardiogram (ECG) during an episode reveals a narrow-complex tachycardia. Vagal maneuvers have failed to prevent recurrences, and her symptoms are significantly impairing her daily activities. A decision is made to initiate chronic prophylactic antiarrhythmic pharmacological therapy. Which of the following medications is considered well-tolerated for use in this pregnant patient?

• ✓ Oral verapamil
• ○ Atenolol
• ○ Amiodarone
• ○ Propafenone

Explanation. Oral verapamil is well-tolerated for the pharmacological treatment of arrhythmias during pregnancy and is a safe choice when maternal antiarrhythmic therapy is required.

Question 159

A 31-year-old woman with a history of type 2 long QT syndrome (LQT2) presents at 37 weeks of gestation for a routine follow-up. She has been stable and asymptomatic on a daily beta-blocker throughout her pregnancy. As she prepares for delivery, she asks about her risk for arrhythmias after childbirth and whether she should adjust her medication. What is the most appropriate management plan regarding her beta-blocker therapy?

• ✓ Continue the beta-blocker therapy uninterrupted throughout the post-partum period, as the risk of cardiac events increases substantially after delivery.
• ○ Discontinue the beta-blocker immediately after delivery, as the physiological stress of pregnancy has resolved and arrhythmia risk normalizes.
• ○ Taper the beta-blocker over the first four weeks post-partum to minimize the risk of maternal bradycardia during the puerperium.
• ○ Replace the beta-blocker with bromocriptine to suppress lactation and simultaneously reduce the risk of post-partum ventricular arrhythmias.

Explanation. In long QT syndrome, particularly type 2 (LQT2), the risk of cardiac events increases substantially in the post-partum period, remaining elevated for up to one year after delivery. Therefore, continuing beta-blocker therapy throughout both pregnancy and the post-partum period is critical to mitigate this heightened arrhythmic risk.

Question 160

A 52-year-old male with end-stage dilated cardiomyopathy is placed on the waiting list for a heart transplantation (HTX). The median expected wait time in his region is approximately 12 months. He is currently not equipped with a defibrillator and is evaluated in the clinic to discuss his risk of sudden cardiac death (SCD) while waiting for a donor heart. Which of the following statements regarding the management of SCD risk in this patient is most accurate?

• ✓ Implantation of an implantable cardioverter-defibrillator (ICD) is supported by large registry data showing a survival benefit, and a wearable cardioverter-defibrillator (WCD) may serve as an alternative in selected patients.
• ○ Device therapy is deferred as randomized trials have definitively shown that ICDs provide no survival benefit for patients listed for HTX.
• ○ Device-based SCD prevention is typically avoided because the median expected time on the HTX waiting list is historically less than 3 months.
• ○ The risk of SCD is only clinically significant after heart transplantation due to allograft vasculopathy and rejection, precluding the need for pre-transplant ICD implantation.

Explanation. Patients listed for heart transplantation are exposed to an increased risk of sudden cardiac death and have a high incidence of ventricular arrhythmias. Data from large registries suggest a survival benefit from implantable cardioverter-defibrillators (ICDs) in this population. Considering the median expected time on the waiting list is 8 to 16 months, a wearable cardioverter-defibrillator (WCD) may be considered as a viable alternative to an ICD in selected patients awaiting transplantation.

Question 161

A 52-year-old asymptomatic man presents to the cardiology clinic for a pre-participation screening. He has decided to start training for his first competitive marathon, which will involve vigorous physical activity. He has no significant past medical history, takes no medications, and has an unremarkable physical examination. Recognizing the most common cause of sudden cardiac death in athletes of his age group, what is the most appropriate initial evaluation strategy for this patient?

• ○ Immediate referral for cardiovascular magnetic resonance (CMR) imaging to rule out arrhythmogenic right ventricular cardiomyopathy
• ✓ Clinical evaluation using a validated cardiovascular risk score system, such as SCORE2
• ○ Routine resting 12-lead electrocardiogram followed by 24-hour Holter monitoring
• ○ Transthoracic echocardiography to primarily screen for left ventricular hypertrophy and structural anomalies

Explanation. In middle-aged and senior athletes, the most common cause of sudden cardiac death is coronary artery disease. Before engaging in vigorous physical activity, asymptomatic middle-aged or senior individuals must undergo initial evaluation utilizing a standardized risk score system, such as SCORE2, to properly quantify and manage their baseline cardiovascular risk.

Question 162

A 19-year-old male collegiate basketball player presents to the sports medicine clinic for pre-participation clearance. He is asymptomatic, has no significant past medical history, and denies any family history of premature sudden cardiac death. To effectively screen for underlying cardiovascular diseases, such as inheritable cardiomyopathies or channelopathies in this young athlete, which combination of initial evaluation modalities is most appropriate?

• ✓ Medical history, physical examination, and an electrocardiogram (ECG)
• ○ Medical history, physical examination, and a routine echocardiogram
• ○ Medical history, physical examination, and a maximal exercise stress test
• ○ Medical history, physical examination, and cardiac magnetic resonance (CMR) imaging

Explanation. Pre-participation evaluation consisting of a medical history, physical examination, and an electrocardiogram (ECG) is effective in identifying cardiovascular disease in young athletes 35 years of age or younger by detecting symptoms or ECG abnormalities consistent with inheritable cardiomyopathies or channelopathies.

Question 163

A 23-year-old male with a documented history of Wolff-Parkinson-White (WPW) syndrome presents to the cardiology clinic. He reports experiencing occasional episodes of a rapid heart rate that start and stop abruptly, which usually resolve with vagal maneuvers. He is concerned about his long-term risks, specifically regarding sudden cardiac death (SCD). Which of the following statements accurately characterizes the most common arrhythmia he is likely to experience and the mechanism of the most feared complication in his condition?

• ○ The most common arrhythmia is atrioventricular nodal re-entry tachycardia (AVNRT), and sudden cardiac death is typically secondary to sustained ventricular tachycardia.
• ✓ The most common arrhythmia is atrioventricular re-entry tachycardia (AVRT), and sudden cardiac death is secondary to pre-excited atrial fibrillation resulting in ventricular fibrillation.
• ○ The most common arrhythmia is atrial fibrillation, and sudden cardiac death is typically a consequence of rapid atrioventricular conduction leading to asystole.
• ○ The most common arrhythmia is primary ventricular fibrillation, which directly leads to sudden cardiac death in the majority of untreated patients.

Explanation. In patients with Wolff-Parkinson-White (WPW) syndrome, the most common arrhythmia is atrioventricular re-entry tachycardia (AVRT), which occurs in approximately 80% of cases. The most feared manifestation of WPW syndrome is sudden cardiac death, which occurs secondary to pre-excited atrial fibrillation that rapidly conducts down the accessory pathway, ultimately degenerating into ventricular fibrillation.

Question 164

A 6-year-old boy is incidentally found to have a delta wave, short PR interval, and widened QRS complex on a 12-lead electrocardiogram (ECG) obtained prior to a planned tonsillectomy. He has never experienced palpitations, syncope, or chest pain, and his physical examination is unremarkable. His parents are anxious about the ECG findings and inquire about further testing to evaluate his risk for sudden cardiac death (SCD). Which of the following is the most appropriate next step in management?

• ○ Refer the patient for an electrophysiology study for invasive risk stratification.
• ○ Perform an exercise stress test to assess for abrupt loss of pre-excitation.
• ✓ Reassure the parents and defer risk stratification until the patient is at least 8 years of age.
• ○ Schedule the patient for prophylactic catheter ablation of the accessory pathway.

Explanation. In children with asymptomatic accessory pathways, risk stratification for sudden cardiac death is not recommended before the age of 8 years. Furthermore, accessory pathways in the pediatric population frequently lose antegrade conduction during the first few years of life.

Question 165

A 77-year-old woman with a history of ischaemic cardiomyopathy and a left ventricular ejection fraction (LVEF) of 28% presents to the clinic to discuss primary prevention with an implantable cardioverter-defibrillator (ICD). She is currently optimized on guideline-directed medical therapy for heart failure. When counseling the patient on the expected benefit of ICD implantation, which of the following statements is most accurate regarding the impact of her age?

• ✓ She is unlikely to derive a significant survival benefit, as age 75 years or older is a predictor of non-arrhythmic mortality and is associated with no ICD benefit.
• ○ She is likely to experience a significant survival benefit, as age 75 years or older is a strong predictor of ventricular tachycardia and fibrillation.
• ○ She will experience a greater survival benefit from an ICD compared to a younger patient, as the association between ICD use and survival increases linearly with age.
• ○ Her age has no significant impact on the expected long-term benefit of an ICD, provided her LVEF remains severely reduced.

Explanation. Advanced age is a strong risk factor for death and is associated with a reduced expected benefit from implantable cardioverter-defibrillator (ICD) treatment. In patients aged 75 years and older, advanced age is a predictor of non-arrhythmic mortality rather than ventricular arrhythmias. Consequently, both randomized trial analyses and prospective cohort studies have demonstrated no significant survival benefit from primary prevention ICD implantation in patients aged 75 years or older.

Question 166

An 81-year-old man with ischemic cardiomyopathy and a left ventricular ejection fraction of 28% is evaluated for a primary prevention implantable cardioverter-defibrillator (ICD). His medical history includes type 2 diabetes mellitus, moderate chronic kidney disease, and osteoarthritis. He is currently asymptomatic on optimal medical therapy, remains physically active, and lives independently. When determining whether to proceed with ICD implantation in this elderly patient, which of the following principles should primarily guide the decision-making process?

• ✓ The decision should be based on a personalized assessment of his overall condition and comorbidities, rather than a simple chronological age cut-off.
• ○ ICD implantation should be withheld because a high chronological age independently negates any primary prevention survival gain.
• ○ The procedure should be routinely approved solely based on his left ventricular ejection fraction, as comorbidities do not alter the survival benefit.
• ○ He must first undergo routine genetic testing for inherited arrhythmia syndromes before determining his eligibility for the device.

Explanation. Biological age varies in part according to comorbidities, which significantly influence the survival of implantable cardioverter-defibrillator recipients. A high comorbidity index is associated with less survival gain in primary or secondary prevention patients. Therefore, a simple age cut-off cannot adequately guide the decision on implantation, and the indication in elderly patients must be based on a personalized assessment considering the overall condition and comorbidities.

Question 167

A 45-year-old male presents with worsening exertional dyspnea and fatigue over the past 4 months. He has no significant past medical history. Echocardiography demonstrates a newly reduced left ventricular ejection fraction (LVEF) of 38% and global hypokinesis. Cardiac magnetic resonance (CMR) imaging shows no late gadolinium enhancement. A 24-hour Holter monitor reveals a 25% burden of monomorphic premature ventricular complexes (PVCs). Coronary angiography reveals no obstructive lesions. Which of the following is the most appropriate first-line management for this patient's underlying condition?

• ○ Initiation of chronic amiodarone therapy
• ○ Implantation of a primary prevention implantable cardioverter-defibrillator (ICD)
• ✓ Catheter ablation of the premature ventricular complexes
• ○ Autonomic modulation via sympathetic denervation

Explanation. Catheter ablation is the established first-line treatment for premature ventricular complex-induced cardiomyopathy, as it directly targets and eliminates the high burden of ectopic beats responsible for the reversible left ventricular dysfunction.