13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

S-6

Prophylactic ICD trials-1997

Stuart J. Connolly.
McMaster University, Hamilton, Canada

The implantable cardioverter defibrillator (ICD) is widely acknowledged to be a major advance in the management of potentially lethal ventricular arrhythmias. Use of the ICD has been increasing dramatically over the past decade in the United States, however, the rate of use per capita remains lower in most countries. Many cardiologists, and cardiac electrophysiologists in particular, have been awaiting the results of randomized clinical trials which have been designed to test the efficacy of the ICD. Recently several of these randomized controlled trials have been reported and the results have been interpreted, by some, to be supportive of a much wider use of the ICD. It is important to review the available data in order to provide optimal evidence based management to patients with lethal ventricular arrhythmias.

The assessment of the overall effectiveness of the ICD is made complex by the fact that ventricular tachycardia (VT) and ventricular fibrillation (VF) are generally not isolated conditions but usually the late complications of ischemic heart disease or cardiomyopathy. Thus the vast majority of patients presenting with VT and VF have multivessel coronary disease and prior myocardial infarction. Although patients with prior sustained VT or VF have a high risk of fatal recurrence of these arrhythmias, they are also as likely to die from another complication of their ischemic heart disease. Thus while the ICD is likely effective against VT and VF episodes it is not obvious that is prolongs life in the average patient treated because of competing risk of death from other causes. Furthermore, amiodarone has been shown to provide a pharmacologic strategy that is at least moderately successful in reducing the risk of arrhythmic death in high risk patients¹. The key question about ICD therapy in the last decade is whether or not it improves survival in patients with sustained VT/VF when compared to the best medical therapy. Trials evaluating ICD therapy are diverse but can be broadly divided into two types according to the target population treated; 1) patients with prior sustained VT or VF, 2) patients without prior sustained VT or VF, but with risk markers for arrhythmic death.

Key Words

Implantable cardioverter defibrillator – function, indications
prophylactic ICD trials, ventricular arrhythmias, CASH trial, CIDS trial, AVID trial, R