20 Dec 09

Defibrillator implantation early after myocardial infarction

Posted in Arrhythmia, Coronary artery disease, ICD at 0:01 by Laci

By G Steinbeck, D Andresen, K Seidl, J Brachmann, E Hoffmann et al; for the IRIS Investigators

NEJM 2009;361:1427-1436

The rate of death, including sudden cardiac death, is highest early after a myocardial infarction. Yet current guidelines do not recommend the use of an implantable cardioverter–defibrillator (ICD) within 40 days after a myocardial infarction for the prevention of sudden cardiac death. We tested the hypothesis that patients at increased risk who are treated early with an ICD will live longer than those who receive optimal medical therapy alone.

Methods
This randomized, prospective, open-label, investigator-initiated, multicenter trial registered 62,944 unselected patients with myocardial infarction. Of this total, 898 patients were enrolled 5 to 31 days after the event if they met certain clinical criteria: a reduced left ventricular ejection fraction (<40%) and a heart rate of 90 or more beats per minute on the first available electrocardiogram (ECG) (criterion 1: 602 patients), nonsustained ventricular tachycardia (>150 beats per minute) during Holter monitoring (criterion 2: 208 patients), or both criteria (88 patients). Of the 898 patients, 445 were randomly assigned to treatment with an ICD and 453 to medical therapy alone.

Results
During a mean follow-up of 37 months, 233 patients died: 116 patients in the ICD group and 117 patients in the control group. Overall mortality was not reduced in the ICD group (hazard ratio, 1.04; 95% confidence interval [CI], 0.81 to 1.35; P=0.78). There were fewer sudden cardiac deaths in the ICD group than in the control group (27 vs. 60; hazard ratio, 0.55; 95% CI, 0.31 to 1.00; P=0.049), but the number of nonsudden cardiac deaths was higher (68 vs. 39; hazard ratio, 1.92; 95% CI, 1.29 to 2.84; P=0.001). Hazard ratios were similar among the three groups of patients categorized according to the enrollment criteria they met (criterion 1, criterion 2, or both).

Conclusions
Prophylactic ICD therapy did not reduce overall mortality among patients with acute myocardial infarction and clinical features that placed them at increased risk.

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