The MADIT-I study was a proof-of-principle study, and this randomized trial showed that the implantable cardioverter defibrillator (ICD) saves lives in high-risk patients with coronary heart disease. The MADIT-II study showed that prophylactic ICD therapy was associated with significantly improved survival in patients with ischemic cardiomyopathy, as defined by documented coronary heart disease and advanced left ventricular dysfunction, without requiring screening for ventricular arrhythmias or inducibility by electrophysiologic testing. Taken together, these two trials, as well as the results from several other randomized ICD trials, indicate that ICD therapy is indicated in coronary patients who meet MADIT-I or MADIT-II eligibility criteria and are not excluded by major noncardiac comorbidity.