Patients who survive ventricular fibrillation or sustained ventricular tachycardia are at high risk for experiencing recurrent, and often fatal, episodes of these arrhythmias. Most of these patients are treated with antiarrhythmic medications, although some have been treated with implantable cardioverter-defibrillators. Neither therapy has been proved to reduce mortality. The Antiarrhythmics versus Implantable Defibrillators Trial compared initial therapy using either an implantable cardioverter-defibrillator or anti-arrhythmic drug therapy with amiodarone or sotalol to determine whether either had an effect on overall survival rates.
Patients were eligible for inclusion in the study if they had been resuscitated from near-fatal ventricular fibrillation or had sustained ventricular tachycardia and hemodynamic compromise. After screening over 6,000 patients, 1,016 were randomized to treatment with antiarrhythmic drugs or an implantable cardioverter-defibrillator. Baseline characteristics of the two groups were almost identical: mean patient age was 65 years, and 79 percent of the patients were men. Of the study subjects, 561 had documented ventricular tachycardia and 455 had ventricular fibrillation. An implantable defibrillator was placed in 507 patients, and 509 were assigned to drug therapy. The drug group was further divided—356 patients were given amiodarone alone because they were not candidates for sotalol therapy, and the remaining 153 were given amiodarone alone or both drugs. Mean ejection fraction was 0.31 in the drug group and 0.32 in the defibrillator group.
After a mean follow-up period of approximately 18 months, crude death rates were 15.8 percent in the defibrillator group and 24.0 percent in the drug groups. After three years, 75.4 percent of the patients in the defibrillator group were still alive, compared with 64.1 percent of the patients in the drug group. In fact, survival rates were better in the defibrillator group throughout the entire course of the study. More specifically, these patients experienced a decrease in death rates of approximately 39 percent at one year, 27 percent at two years and 31 percent at three years after enrollment in the study. The rate of medical or surgical complications in all patients was not significantly different.
The authors conclude that therapy with the implantable cardioverter-defibrillator is superior to drug therapy in improving survival in patients who have been resuscitated from ventricular fibrillation or who have sustained symptomatic ventricular tachycardia. They believe that the implantable cardioverter-defibrillator should be offered as first-line therapy for patients with potentially fatal ventricular arrhythmias.