Primary Prevention of Sudden Death as a Novel Treatment Strategy in Hypertrophic Cardiomyopathy

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Abstract
Case Report : A 20-year-old asymptomatic man was diagnosed with hypertrophic cardiomyopathy (HCM) after routine physical examination during which a systolic heart murmur was detected. Echocardiography showed massive left ventricular (LV) hypertrophy with ventricular septal thickness of 36 mm extending into the anterolateral wall (30 mm); outflow obstruction was absent. Ambulatory (Holter) ECG showed 3 isolated premature ventricular contractions, and blood pressure response to exercise was normal. Echocardiographic examinations in parents and siblings were negative for HCM. Although 2 centers advised against an implantable cardioverter-defibrillator (ICD) based on the presence of only 1 risk factor for sudden death (ie, extreme hypertrophy), a prophylactic device was recommended by a third cardiac consultant. After an uneventful 16-month period during which the ICD neither detected nor treated arrhythmias, an unprovoked episode of ventricular fibrillation triggered a defibrillation shock that immediately restored sinus rhythm (Figure 1). Figure 1. Primary prevention of sudden death in HCM. Continuous recording of a stored intracardiac ventricular electrogram from a young asymptomatic man with extreme LV hypertrophy (septal thickness 36 mm). The ICD senses ventricular fibrillation and automatically delivers a defibrillation shock (arrow), which restores normal rhythm. HCM is the most common genetic cardiovascular disease, and since its description 45 years ago, sudden death has been its most visible and devastating consequence.1–5 Indeed, HCM is the most common cause of sudden cardiac death in young people (including trained athletes).5 Such events usually occur in previously healthy individuals without significant symptoms or as the initial clinical manifestation of the disease, thus generating considerable anxiety and a sense of vulnerability among patients and families.2–5 Identification of high-risk patients and efforts at prevention of sudden death represent important clinical challenges in HCM.6 The ICD was introduced 25 years ago as a treatment strategy for lethal ventricular tachyarrhythmias.7 …