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Prophylactic ICD implanted soon after MI does not improve survival

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Implantation of a cardioverter-defibrillator (ICD) early after acute myocardial infarction does not decrease overall mortality, investigators report October 8 in The New England Journal of Medicine.

In the European IRIS (Immediate Risk-Stratification Improves Survival) trial, patients randomized to treatment with an ICD had a lower risk of sudden cardiac death but a higher risk of nonsudden cardiac death.

To be included in the study, patients were required to have nonsustained ventricular tachycardia at some point on days 5 to 31, or a heart rate of at least 90 beats per minute on the first available ECG after MI and an ejection fraction of 40% or less on one of days 5 to 31.

The goal of the trial was to show that ICD implantation early after MI in patients with these “predefined markers of elevated risk” would improve their survival. Current guidelines, the article points out, recommend that ICD implantation be delayed for at least 40 days after an acute MI.

Of the eligible 898 patients who agreed to participate, 445 were randomly assigned to undergo ICD implantation and 453 to receive regular medical therapy alone at a mean of 13 days after MI.

Led by Dr. Gerhard Steinbeck at Ludwig-Maximilians University in Munich and Dr. Dietrich Andresen at Klinikum am Urban in Berlin, the researchers report there was no significant difference in survival between the treatment groups. Within 30 days, there were 9 deaths in the ICD group and 11 among controls. During an average follow-up of 37 months, 116 patients in the ICD group and 117 in the control group died. Death rates were similar at 1, 2 and 3 years.

There were fewer sudden cardiac deaths in the ICD group than in the control group (27 vs. 60; hazard ratio, 0.55), but the number of non-sudden cardiac deaths was higher (68 vs 39; hazard ratio, 1.92).

Editorialists from Stanford University in Palo Alto, California, contend that “ICDs benefit selected patients, but the IRIS trial confirmed that they do not benefit all patients at high risk for sudden cardiac death.”

This result, Drs. Alan M. Garber and Mark A. Hlatky add, “can direct efforts away from an expensive yet ineffective procedure toward either new or established alternatives.”

N Engl J Med 2009;361:1427-1436,1498-1499.