REVERSION OF RECENT-ONSET ATRIAL-FIBRILLATION TO SINUS RHYTHM BY INTRAVENOUS FLECAINIDE

Spontaneous reversion to sinus rhythm is a frequent occurrence in recent-onset atrial fibrillation (AF). In a randomized, double-blind, controlled study, intravenous flecainide (2 mg/kg, maximum dose 150 mg) was compared with placebo in the treatment of recent-onset AF (present for greater-than-or-equal-to 30 minutes and less-than-or-equal-to 72 hours' duration and a ventricular response greater-than-or-equal-to 120 beats/min). Intravenous digoxin (500-mu-g) was administered concurrently to all patients in both groups who had not previously taken digoxin. The trial medication was administered over 30 minutes. Exclusion criteria included hemodynamic instability, severe heart failure, recent antiarrhythmic therapy, hypokalemia and pacemaker dependence. One hundred two consecutive patients with recent-onset AF were enrolled in the study. All patients underwent continuous electrocardiographic monitoring in the intensive care or coronary care unit. Twenty-nine (57%) patients given flecainide and digoxin, but only 7 (14%) given placebo and digoxin, reverted to sinus rhythm in less-than-or-equal-to 1 hour after starting the trial medication infusion and remained in stable sinus rhythm (chi-square 18.9, p = 0.000013; odds ratio 8.3, 95% confidence interval 2.9 to 24.8). At the end of the 6-hour monitoring period, 34 patients (67%) in the flecainide-digoxin group were in stable sinus rhythm, whereas only 18 patients (35%) in the placebo-digoxin group had reverted (chi-square 8.83, p = 0.003; odds ratio 3.67, 95% confidence interval 1.5 to 9.1). Severe hypotension, although transient, was more common in the flecainide-digoxin group. Flecainide is effective in reverting recent-onset AF, but should not be given to patients with severe left ventricular dysfunction because the risks may outweight the potential benefits of reversion to sinus rhythm.