Prevention of Sudden Death in Hypertrophic Cardiomyopathy

C ase presentation: A 14-yearold girl died suddenly and unexpectedly while exercising. Clinical and echocardiographic family screening identified hypertrophic cardiomyopathy (HCM) in her only sibling, an asymptomatic 17-year-old boy. In her brother, echocardiography showed extreme septal ventricular hypertrophy, 35 mm in thickness; left ventricular (LV) outflow obstruction was absent. Left atrial dimension was 42 mm. Holter monitoring showed 2 runs of nonsustained ventricular tachycardia (5 and 8 beats). Blood pressure response during exercise was normal. The patient was judged to be at high risk for sudden death and a candidate for an implantable cardioverter-defibrillator (ICD). The overall favorable clinical profile (ie, no symptoms, preserved systolic function, and low risk of developing atrial fibrillation [AF]) suggested that long-term survival principally relied on effective prevention of sudden death. Therefore, ICD selection centered on the longterm reliability of the ICD system, particularly the leads. A singlechamber ICD with a single-coil activefixation lead was implanted to facilitate extraction should lead removal be required. Moreover, a high–shock output ICD was used because of the massive LV hypertrophy and possible high defibrillation threshold.