Intravenous flecainide versus Amiedarone fof recent-onset atrial fibrillation

In a randomized, double-blind, controlled study of 98 patients with atrial fibrillation (AF) (present for ≥30 minutes, ≤72 hours, and a ventricular response of ≥100 beats/min), intravenous flecainide (2 mg/kg, maximum 150 ma) was compared with intravenous amiodarone (7 mg/kg) and placebo. Exdusion criteria included significant left ventricular dysfunction, inotrope dependence, recent antiarrhythmic therapy, hypokalemia, and pacemaker dependence. Reversion to stable sinus rhythm within 2 hours of starting medication was considered likely to be due to drag effect. Twenty of 34 patients (59%) given flecainide, 11 of 32 (34%) given amiodarone, and 7 of 32 (22%) given placebo reverted to stable sinus rhythm in ≤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% confidence interval 1.54 to 17.5). There was no significant difference between amiodarone and placebo or between flecainide and amiodarone. However, after 8 hours there were no significant differences in reversion between the treatment group: flecainide (n = 23,68%), amiodarone (n = 19, 59%), and placebo (n = 18,56%). Amiodarone promptly reduced the ventricular rote, and this effect was maintained for 8 hours in those whose reversion to stable sinus rhythm was unsuccessful: flecainide was no more effective than placebo in controlling ventricular rate. Adverse effects were not significantly different in the 3 groups. Thus, intravenous flecainide results in earlier reversion of AF than does intravenous amiodarone or placebo. Amiodarone, although less effective in reverting AF, slows the rapid ventricular response. Drug treatment may be unnecessary for recent-onset AF, especially if patients are hemoaynamically stable and without significant symptoms: Nearly 60% of patients will return to sinus rhythm within a few hours without any treatment.