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Should We Recommend Automatic Defibrillators for Patients with MIs and Low Ejection Fractions?

Prophylactic defibrillator implantation lowered mortality in patients with advanced left ventricular dysfunction after myocardial infarction.

Patients with substantially reduced ejection fractions after myocardial infarctions clearly are at high risk for ventricular arrhythmia, but do they benefit from prophylactic implantation of defibrillators? In a new study, investigators from the Multicenter Automatic Defibrillator Implantation Trial II weigh in on this question.

A total of 1232 patients with prior MIs and ejection fractions of 30% or less were randomized to receive implantable defibrillators or conventional medical therapy; patients were not required to undergo electrophysiologic screening. After an average follow-up of 20 months, mortality was significantly lower in the defibrillator group than in the medical-therapy group (20% vs. 14%). Similar benefit of defibrillator therapy was seen in multiple subgroup analyses. Use of adjunctive medical therapy was comparable in the 2 groups. Defibrillators generally were well tolerated, but there was a trend toward increased incidence of new, or worsened, heart failure in the device group.

Comment: Prophylactic defibrillator implantation improved overall survival for patients with MIs and advanced left ventricular dysfunction. The authors estimate that their findings might apply to as many as 3 to 4 million patients in the U.S. with coronary heart disease and low ejection fractions, which would carry substantial cost to our health care system. One might hope that further research will clarify which of these patients would benefit most, although the relatively homogeneous subgroup analyses in this study do not provide clear direction to guide such additional research.

— Kirsten E. Fleischmann MD, MPH

Published in Journal Watch General Medicine April 16, 2002

Citation(s):

Moss AJ et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002 Mar 21; 346:877-83.

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