Primary Prevention Implantable Cardiac Defibrillator Trials: What Have We Learned?

Patients with impaired left ventricular systolic function frequently die suddenly because of arrhythmic and nonarrhythmic causes. Nine trials have evaluated the utility of implantable cardioverter-defibrillator (ICDs) primary prevention of sudden cardiac death. Individuals with stable ischemic heart disease (no recent myocardial infarction), especially those with inducible arrhythmias, seem to derive the highest mortality benefit from prophylactic ICD use. The role of ICDs in other patient populations is much less clear and may even be harmful. The use of antiarrhythmic medications has not been shown to improve survival in any patient population at risk for sudden death.