BENEFIT AND RISKS OF LONG-TERM AMIODARONE THERAPY FOR SUSTAINED VENTRICULAR-TACHYCARDIA FIBRILLATION - MINIMUM OF 3-YEAR FOLLOW-UP IN 145 PATIENTS

Our experience with amiodarone therapy in 145 consecutively referred patients with medically refractory sustained ventricular tachycardia and/or fibrillation treated for at least 3 years was reviewed. Ninety-seven had sustained ventricular tachycardia; the remaining 48 patients were survivors of sudden cardiac death. The patients had a mean of 3.7±1.4 unsuccessful anti-arrhythmic drug trials before initiation of amiodarone. The initial doses of amiodarone averaged 845±258 mg for the first 2 weeks and 56% of all patients received a type 1 antiarrhythmic drug in addition to amiodarone during the initial phase of therapy. The average maintenance dose of amiodarone was 410±187 mg per day. All patients were followed for a minimum of 3 years or until death or withdrawal from therapy. The maximum follow-up was a period of 8 years. Thus, the average duration of amiodarone therapy was 39±26 months, representing 472 patient years of therapeutic time on amiodarone. The incidence of deaths either caused by a documented ventricular tachyarrhythmia or presumed to result from an arrhythmic cause was 5.5% in the first year and 3.4% in each of the second and third years of follow-up. During the entire period of follow-up, 56 patients died of all causes (38.6% of the study population). Survival over the follow-up period was influenced significantly by left ventricular function, as judged by either New York Heart Association Functional Class or objective assessment of left ventricular ejection fraction, which was available in 102 patients. Seventeen percent of the patients had to be withdrawn from the study because of side effects to amiodarone, including 6% caused by pulmonary toxicity. In summary, we have found amiodarone to be highly effective in prophylaxis of arrhythmic deaths in a high-risk population of patients referred for refractory life-threatening ventricular arrhythmias. The observed incidence of arrhythmic deaths during the minimum follow-up period of 3 years in these 145 patients should be balanced against the withdrawal rate of 17%, necessitated by side effects from amiodarone. © 1990 Mosby-Year Book, Inc.