INTRAVENOUS FLECAINIDE VERSUS AMIODARONE FOR RECENT-ONSET ATRIAL-FIBRILLATION

In a randomized, double-blind, controlled study of 98 patients with at rial fibrillation (AF) (present for greater than or equal to 30 minute s, less than or equal to 72 hours, and a ventricular response of great er than or equal to 100 beats/min), intravenous flecainide (2 mg/kg, m aximum 150 mg) was compared with intravenous amiodarone (7 mg/kg) and placebo. Exclusion criteria included significant left ventricular dysf unction, inotrope dependence, recent antiarrhythmic therapy, hypokalem ia, and pacemaker dependence. Reversion to stable sinus rhythm within 2 hours of starting medication was considered likely to be due to drug effect. Twenty of 34 patients (59%) given flecainide, 11 of 32 (34%) given amiodarone, and 7 of 32 (22%) given placebo reverted to stable s inus rhythm in less than or equal to 2 hours after starting medication (chi-square 9.87, p = 0.007). More patients reverted to stable rhythm with flecainide than with placebo (p = 0.005; odds ratio 5.1, 95% con fidence interval 1.54 to 17.5). There was no significant difference be tween amiodarone and placebo or between flecainide and amiodarone. How ever, after 8 hours there were no significant differences in reversion between the treatment groups: flecainide (n = 23, 68%), amiodarone (n = 19, 59%), and placebo (n = 18, 56%). Amiodarone promptly reduced th e ventricular rate, and this effect was maintained for 8 hours in thos e whose reversion to stable sinus rhythm was unsuccessful: flecainide was no more effective than placebo in controlling ventricular rate. Ad verse effects were not significantly different in the 3 groups. Thus, intravenous flecainide results in earlier reversion of AF than does in travenous amiodarone or placebo. Amiodarone, although less effective i n reverting AF, slows the rapid ventricular response. Drug treatment m ay be unnecessary for recent-onset, AF, especially if patients are hem odynamically stable and without significant symptoms: Nearly 60% of pa tients will return to sinus rhythm within a few hours without any trea tment.