MADIT-II: substudies and their implications.

In MADIT-II, prophylactic ICD therapy was effective in improving survival in patients with prior myocardial infarction and an ejection fraction <or=0.30, and a host of prespecified secondary analyses indicate that life-saving effect of ICD therapy is consistent across all studied subgroups. We have not been able to identify any traditional risk factors that will permit selection of patients who will receive a significantly better effect from the ICD within any subgroup. The ICD provides appropriate therapy for life-threatening ventricular arrhythmias on at least one occasion in over a third of the patients during the first 4 years after device implantation. Computations from the MADIT-II database indicate that 9 patients need to be treated with an ICD to save one life during a 4-year period. The findings from MADIT-II have implications for patients, physicians, and society.