Evidence-based medicine and the implantable defibrillator.

Evidence from recent randomized clinical trials now strongly supports the use of the implantable defibrillator, as treatment of first choice, in patients who have experienced symptomatic, sustained ventricular tachyarrhythmias. Little or no controversy remains on this question, either among physicians or third-party players. The evidence-based use of the defibrillator as primary preventative therapy (that is, for patients who have an increased risk for lethal arrhythmias, but who have not yet experienced them) is far more limited. Two randomized trials have now demonstrated a survival benefit with the defibrillator in patients who have ischemic heart disease; reduced left ventricular ejection fraction; documented nonsustained ventricular tachycardia; and inducible sustained ventricular tachycardia during electrophysiologic testing that is not suppressed by at least one drug trial. Based on the strength of this recently available information, the screening of appropriate patients, while admittedly inconvenient, ought to be strongly considered. The broader use of the implantable defibrillator in the primary prophylaxis of arrhythmic sudden death will have to await the results of future trials.