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ICDS BENEFICIAL IN A MORE EASILY IDENTIFIABLE POPULATION

Implantable cardioverter-defibrillators (ICDs) prolong survival in patients with ischemic cardiomyopathy and a positive electrophysiology study (Journal Watch Cardiology Jan 21 2000). The MADIT II trial was designed to determine whether ICDs prolong survival in a more easily identifiable population: patients with prior MI and LV ejection fractions of 30%. A total of 1232 such patients were randomized in a 3:2 ratio to either ICD implantation or conventional medical therapy; mean follow-up was 20 months. Demographic features of the 2 groups were similar: For example, 70% of both received concomitant beta-blocker therapy; both had mean LVEFs of 23%.

The mortality rate was 31% lower in the ICD group than in the conventional-therapy group (14.2% vs. 19.8%, P=0.016) -- an effect that persisted after stratification by age, sex, LVEF, NYHA class, and QRS interval. Complications related to ICD implantation included lead problems (1.8%) and nonfatal infection (0.7%), but no deaths. A trend toward more new or worsening heart failure emerged in the ICD group (19.9% vs. 14.9%, P=0.09).

Comment: These results show, for the first time, that prophylactic ICD placement improves survival in patients with prior MI and LVEFs 30%. Both the magnitude of benefit (31% mortality-risk reduction) and the simplicity of the approach are striking. Notably, electrophysiology testing was not used to identify high-risk patients. The data suggest that ICDs should be considered for all patients with ischemic cardiomyopathy. The authors hope that if a significant proportion of the more than 3 million patients with coronary artery disease and advanced LV dysfunction receive ICDs, market forces will drive down costs. Clearly, such a scenario's cost-effectiveness should be studied formally. Also, the precise reason for increased heart-failure hospitalizations among ICD recipients must be explored.

— Hugh Calkins, MD

Published in Journal Watch Cardiology January 1, 2003

Citation(s):

Moss AJ et al. for the Multicenter Automatic Defibrillator Implantation Trial II Investigators. 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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Bigger JT. Expanding indications for implantable cardiac defibrillators. N Engl J Med 2002 Mar 21; 346:931-3.

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