Implanted cardioverter defibrillators for the prevention of sudden death.

Implantable cardioverter defibrillators (ICDs) are effective in preventing sudden death from ventricular arrhythmias. Recent clinical trials have demonstrated reductions in all-cause mortality in ICD-treated patients, especially those with severe left ventricular dysfunction. However, selecting appropriate patients for ICD implantation, especially for the primary prophylaxis of all-cause death, is a challenge. Patients with recent myocardial infarction (less than 40 days) or those that have just undergone coronary artery bypass graft surgery do not benefit from ICD implantation. On average, annual death rates are reduced by 1.5% to 3.0%, but the risk of death in an individual patient is hard to quantify. Poor left ventricular function is the best predictor of both mortality risk and ICD benefit. Other risk predictors need to be identified.