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Do ICDs Reduce the Risk for Sudden Death in Patients with HCM?

About 5% of patients received appropriate discharges each year in this observational study.

The implantable cardioverter-defibrillator (ICD) is being used to reduce the risk for sudden death in many patients with hypertrophic cardiomyopathy (HCM). Whether these devices in fact are saving many lives is not known.

Investigators studied 506 unrelated patients with HCM identified on echocardiography who received an ICD at one of 42 centers in the U.S., Europe, and Australia. The average age of the patients was 42 years, and most received ICDs for primary prevention (n=383).

During a mean follow-up of 3.7 years, 20% of the patients had an appropriate device intervention, with the device terminating ventricular fibrillation or tachycardia and restoring sinus rhythm. Inappropriate shocks occurred in 27% of patients. The rate of appropriate intervention was 5.5% per year. Almost all (90%) of the patients with appropriate ICD interventions had no or mild symptoms of heart failure. The appropriate-discharge rate was higher (42%) in patients who received the device for secondary prevention. In the primary-prevention patients, the discharges were unrelated to risk factors (syncope, history of premature death in a relative, massive left ventricular hypertrophy, and runs of nonsustained ventricular tachycardia). ICD complications included lead fracture (7%), infection (4%), and hemorrhage/thrombosis (2%).

Comment: This study of relatively young patients with hypertrophic cardiomyopathy who received an implantable cardioverter-defibrillator reveals a relatively high rate of appropriate device intervention, suggesting that the devices provided important protection from sudden death in this population. The intervention rates did not differ significantly according to whether patients had one, two, or three or more risk factors. The editorialists estimate that 250,000 people in the U.S. have HCM with at least one risk factor for sudden death. The complication rate in this study was not trivial, and the generalizability of the findings to all patients with HCM is not clear, but given these findings, many patients with HCM and at least one risk factor may reasonably ask to receive an ICD.

— Harlan M. Krumholz, MD, SM

Published in Journal Watch Cardiology August 15, 2007

Citation(s):

Maron BJ et al. Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy. JAMA 2007 Jul 25; 298:405-12.

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Nishimura RA and Ommen SR. Hypertrophic cardiomyopathy, sudden death, and implantable cardiac defibrillators: How low the bar? JAMA 2007 Jul 25; 298:452-4.

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