Use of traditional and biventricular implantable cardiac devices for primary and secondary prevention of sudden death.

Sudden cardiac death is the leading cause of cardiac mortality, particularly among high-risk populations with known left ventricular systolic dysfunction. Multiple randomized clinical trials demonstrated a significant mortality benefit of the implantable cardioverter defibrillator (ICD) compared with antiarrhythmic drug therapy or standard medical care. Initial ICD trials showed a mortality improvement for patients who previously had experienced aborted sudden cardiac death or sustained ventricular tachycardia (secondary prevention). Primary prevention trials in selected high-risk patients who had both ischemic and nonischemic cardiomyopathy also demonstrated a mortality benefit associated with ICD treatment. More recently, cardiac resynchronization therapy with or without defibrillator capability has been shown to reduce morbidity and mortality among advanced heart failure patients with a prolonged QRS duration.