Sudden cardiac death accounts for 400,000 to 450,000 deaths annually in Europe and in the United States. In patients with previous life-threatening
arrhythmia, several perspective, randomized, controlled studies have demonstrated that
implantable cardioverter-defibrillator (ICD)
therapy is superior to the best antiarrhythmic
therapy in prolonging survival. Furthermore, in a stratified-risk population with
coronary artery disease, left ventricular ejection fraction < or = 35%, non-sustained ventricular arrhythmias, and inducible
ventricular tachycardia, the ICD supports the class I level of recommendation by the guidelines published in 1998. The American College of Cardiology, American Heart Association, and North American Society of Pacing and Electrophysiology have updated the 1998 guidelines on the implantation of
arrhythmia devices including in a class IIa level of recommendation also patients with a previous Q wave
myocardial infarction and left ventricular ejection fraction < or = 30%, independently of their arrhythmic risk profile. In the recent years several randomized studies assessed the role of ICD treatment for primary prevention of
sudden cardiac death and total mortality reduction in high-risk groups of patients with ischemic and non-ischemic
dilated cardiomyopathy, with special reference to those with
heart failure and
ventricular dysfunction. This article reviews those trials that have resulted in defining indications for ICD, and that will expand its use in the future.