Principal Findings:

Among randomized patients, the initial phases of the trial have acceptable mortality (overall surgical mortality = 5.9%), morbidity (cardiopulmonary bypass = 23%; shock = 8%; deep sternal wound infection = 1.3%), and length of stay (median = 8 days). During an average follow-up of 32 ± 16 months, there were 101 deaths in the defibrillator group (71 from cardiac causes) and 95 deaths in the control group (72 from cardiac causes). The hazard ratio for death from any cause was 1.07 (95% confidence interval 0.81-1.42, p=0.64).

The original design called for 800 patients to be randomized to ICD prophylaxis or to no therapy, and followed for two to 6.5 years (average, 40 months) to a common termination date. Because the ICD pulse generators used in this trial lasted about 42 months, the original design required ICD replacement in many patients.

In June 1994, an unanticipated subpoena from the Office of the Inspector General made it impossible to replace about half of the ICD generators, and threatened to shorten follow-up substantially. After reviewing many options for restoring power, the Data Safety and Monitoring Board recommended that the sample size be increased from 800 to 900 patients, and that almost all patients be followed for 42 months. This recommendation extended follow-up for two years beyond the original termination date planned for the trial.