PILOT-STUDY AND PROTOCOL OF THE CANADIAN TRIAL AT ATRIAL-FIBRILLATION(CTAF)

Antiarrhythmic drug prophylaxis in patients with atrial fibrillation ( AF) is associated with a high incidence of arrhythmic recurrence. Unco ntrolled studies have suggested that low-dose amiodarone may be superi or in terms of efficacy to other antiarrhythmic drugs while having an acceptable side effect profile. The Canadian Trial of Atrial Fibrillat ion (CTAF) is a 25-center study sponsored by tile Medical Research Cou ncil of Canada to determine the best treatment strategy to maintain si nus rhythm in patients with persistent or paroxysmal AF. Recruitment b egan in November 1996 and will continue for 1.5 years. Patients are ra ndomized to receive either low-dose amiodarone or conventional antiarr hythmic drug therapy. Patients assigned to the amiodarone group will r eceive an oral loading regimen of 10 mg/kg/day during a minimum 14-day period. Patients assigned to conventional antiarrhythmic therapy will receive 1 of 2 agents commonly used in AF prophylaxis: sotalol or pro pafenone. Drug selection and loading, and electrical cardioversion, if necessary, will be performed within 21 days of randomization. The lon g-term maintenance dose of amiodarone is 200 mg/day. We have planned a minimum follow-up period of 1 year. The primary end point is the time to the first relapse of AF. Data will be analyzed on an intention-to- treat basis. Secondary outcomes are medication toxicity, mortality, ma jor clinical events, costs of each approach, and quality of life. For the purpose of sample size calculations, it is anticipated that recurr ence of AF at 1 year will occur in 50% of patients on conventional tre atment compared with 35% in those receiving amiodarone. In order to ha ve an 80% power and a 2-tailed type I error of 0.05, assuming a 15% lo ss to follow-up rate, a total sample size of 400 patients will be requ ired. A pilot study done at the Montreal Heart Institute has shown tha t the research protocol is feasible. (C) 1997 by Excerpta Medica, Inc.