Review Question - QID 214533

This young athlete's episode of syncope and evidence of left ventricular hypertrophy and systolic anterior motion of the mitral valve is consistent with hypertrophic cardiomyopathy. This patient's syncopal episode and family history of sudden cardiac death make an implantable cardioverter-defibrillator indicated for primary prevention of sudden cardiac death.

Hypertrophic cardiomyopathy is an autosomal dominant genetic disorder involving cardiac sarcomeres. Patients can present with fatigue, dyspnea, chest pain, palpitations, presyncope, and/or syncope. Left ventricular hypertrophy can be significant enough to result in a left ventricular outflow tract obstruction. A dangerous consequence of this condition is the development of sudden cardiac death. An implantable cardioverter-defibrillator is indicated for the primary and secondary prevention of sudden cardiac death. Primary prevention is indicated if there is a family history of sudden cardiac death, nonsustained ventricular tachycardia, and ≥ 30 mm maximum ventricular septa wall thickening. Secondary prevention is indicated in patients who survived a cardiac arrest or have sustained ventricular arrhythmias.

Incorrect Answer:
Answer 1: Alcohol septal ablation is a procedure where the myocardium is locally infarcted in the area of the basal septal muscle. The goal of this procedure is to relieve the obstruction but is typically reserved for when patient symptoms are not relieved with medical therapy (e.g., beta-blockers). It is not indicated to prevent the development of sudden cardiac death and may increase the risk of developing cardiac arrhythmias (e.g., ventricular tachycardia) and sudden cardiac death.

Answer 2: Amlodipine is a dihydropyridine calcium channel blocker that preferentially decreases systemic vascular resistance, which would worsen the left ventricular outflow tract gradient, and lead to obstruction. Of the calcium channel blockers, verapamil is typically used in patients who cannot take beta-blockers for symptoms of heart failure.

Answer 3: Cardiac catheterization would be considered if evaluating for obstructive coronary disease, when the clinical and imaging studies are discrepant in patients with left ventricular outflow obstruction, and pre-cardiac transplant. This will not prevent a future sudden cardiac death event.

Answer 5: Pacemaker therapy is reserved for patients who are not candidates for myomectomy or alcohol septal ablation to manage symptoms of left ventricular outflow tract obstruction. Pacemaker therapy is not used in decreasing the risk of sudden cardiac death.

Bullet Summary:
Implantable cardioverter-defibrillator is used to prevent sudden cardiac death in patients who have hypertrophic cardiomyopathy and an increased risk of developing sudden cardiac death (e.g., syncope and family history of sudden cardiac death).