The Clinical Use of Implantable Cardioverter Defibrillators: Where Are We Now? Where Should We Go?

Cardiovascular disease mortality continues to decline, but patients with left ventricular dysfunction, especially if it results from coronary artery disease, remain at high risk for both sudden and nonsudden death (1-4). In 1998, the latest year for which U.S. statistics are available, sudden cardiac death occurred in 456 076 persons, accounting for more than 60% of cardiac deaths (5). Overall, age-adjusted sudden death decreased 8.3% from 1989 to 1998. Sudden death decreased 11.7% in men, but only 5.8% in women; in fact, sudden death in women 35 to 44 years of age increased 21% over the 10-year period. The proportion of cardiac deaths in persons who did not survive to receive medical care has also increased. In 1989, 37.8% of cardiac deaths were sudden and out-of-hospital versus 46.7% in 1998. Thus, there remains a pressing need to apply more effective prophylaxis against sudden cardiac death.

The implantable defibrillator, introduced to clinical medicine in 1980, has revolutionized the care of patients with life-threatening cardiac arrhythmias. The use of the implantable cardioverter defibrillator (ICD) has increased steadily because of technical refinements and a plethora of clinical trials demonstrating its utility. Along with technical improvements in the ICD, there has been increasing appreciation of the deleterious effects of many pharmacologic antiarrhythmic agents in patients with heart disease, as first shown in the Cardiac Arrhythmia Suppression Trial (CAST) (6). The ICD effectively terminates most episodes of ventricular fibrillation and ventricular tachycardia by pacing or shock. It differs from antiarrhythmic drugs because its efficacy is not dependent on patient adherence; , its mode of action is fairly straightforward; and, in the hands of well-trained physicians, it is associated with very low risk. The ICD's ability to reduce mortality appears to depend only on the fact that it can rapidly terminate ventricular tachyarrhythmias, …