Prophylactic Use of Implanted Cardiac Defibrillators in Patients at High Risk for Ventricular Arrhythmias after Coronary-Artery Bypass Graft Surgery

BACKGROUND: Patients with coronary heart disease, left ventricular dysfunction, and abnormalities on signal-averaged electrocardiograms have an increased risk sudden death. We evaluated the effect on survival of the prophylactic implantation of cardioverter-defibrillators in such patients at the time of coronary-artery bypass surgery. METHODS: Over the course of five years, 37 clinical centers screened all patients who were scheduled for elective coronary bypass surgery. Patients were eligible for the trial if they were less than 80 years old, had a left ventricular ejection fraction of less than 0.36, and had abnormalities on signal-averaged electrocardiograms. We identified 1422 eligible patients, enrolled 1055, and randomly assigned 900 to therapy with an implantable cardioverter-defibrillator (446 patients) or to the control group (454 patients). The primary end point of the study was overall mortality, and the two groups were compared in an intention-to-treat analysis. RESULTS: The base-line characteristics of the two groups were similar. During an average follow-up of 32+/-16 months, there were 101 deaths in the defibrillator group (71 from cardiac causes) and 95 in the control group (72 from cardiac causes). The hazard ratio for death from any cause was 1.07 (95 percent confidence interval, 0.81 to 1.42; P=0.64). There was no statistically significant interaction between defibrillator therapy and any of 10 preselected base-line covariates. CONCLUSIONS: We found no evidence of improved survival among patients with coronary heart disease, a depressed left ventricular ejection fraction, and an abnormal signal-averaged electrocardiogram in whom a defibrillator was implanted prophylactically at the time of elective coronary bypass surgery.