Prevention of Sudden Death in Hypertrophic Cardiomyopathy But Which Defibrillator for Which Patient? Giuseppe Boriani, MD, PhD; Barry J. Maron, MD; Win-Kuang Shen, MD; Paolo Spirito, MD C ase presentation: A 14-year- old girl died suddenly and un- expectedly while exercising. Clinical and echocardiographic family screening identified hypertrophic car- diomyopathy (HCM) in her only sib- ling, an asymptomatic 17-year-old boy. In her brother, echocardiography showed extreme septal ventricular hy- pertrophy, 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 fibril- lation [AF]) suggested that long-term survival principally relied on effective prevention of sudden death. Therefore, ICD selection centered on the long- term reliability of the ICD system, particularly the leads. A single- chamber ICD with a single-coil active- fixation lead was implanted to facili- tate extraction should lead removal be required. Moreover, a high–shock out- put ICD was used because of the mas- sive LV hypertrophy and possible high defibrillation threshold. Background During the past few years, interest has increased in the use of the ICD in genetic cardiac diseases associated with sudden cardiac death, such as HCM, long-QT syndrome, arrhythmo- genic right ventricular cardiomyopa- thy, and Brugada syndrome. 1,2 HCM is by far the most common of these cardiac conditions, with a prevalence of about 1:500 in the general popula- tion. 3,4 Because most HCM patients at high risk for sudden death are young, with no or only mild symptoms and preserved systolic function, prevention of sudden death by the ICD may pro- long life substantially in this disease and could offer a normal or near- normal life expectancy to many pa- tients. 1,4,5 Indeed, recent investigations have shown that the ICD is effective in preventing sudden death in HCM. 1,6 In a multicenter study of high-risk HCM patients, the device intervened appro- priately and terminated ventricular tachycardia or fibrillation at a rate of 5% per year for primary prevention and 11% per year for secondary pre- vention, over an average follow-up of 3 years. 1 The number of HCM patients implanted with an ICD also has in- creased substantially over the past few years. Therefore, a large ICD cohort is now emerging that differs from the general ICD population because of younger age, lower rate of life- threatening events, and longer ex- pected survival. Consequently, in such patients, the selection of the most ap- propriate ICD system with adequate long-term reliability has become criti- cally important, and the complexity of such decisions is enhanced by the clin- ical heterogeneity of HCM. The 2002 American College of Car- diology/American Heart Association/ North American Society of Pacing and Electrophysiology consensus guide- lines do not address the specific issue of lead and device selection in HCM and are largely based on trials per- From the Istituto di Cardiologia, Università di Bologna, Azienda Ospedaliera S. Orsola-Malpighi, Bologna, Italy (G.B.); Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, Minn (B.J.M.); Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minn (W.-K.S.); and Divisione di Cardiologia, Ente Ospedaliero Ospedali Galliera, Genoa, Italy (P.S.). Correspondence to Giuseppe Boriani, MD, PhD, Istituto di Cardiologia, Università di Bologna, Policlinico S. Orsola, Azienda Ospedaliera S. Orsola-Malpighi, Via Massarenti 9, 40138, Bologna, Italy. E-mail cardio1@med.unibo.it (Circulation. 2004;110:e438-e442.) © 2004 American Heart Association, Inc. Circulation is available at http://www.circulationaha.org DOI: 10.1161/01.CIR.0000144463.65977.C9 CLINICIAN UPDATE e438 Downloaded from http://ahajournals.org by on January 11, 2022