Aims: This study compared the efficacy and safety of intravenous flecainide and ibutilide for immediate cardioversion of atrial fibrillation (AF).
Methods and results: We conducted a prospective, randomised trial, including 207 patients with AF of recent onset (< or = 48 h). Flecainide was given over 20 min at a dose of 2 mg/kg body weight (maximum 200 mg), ibutilide was infused at a dose of 1 mg (or 0.01 mg/kg if less than 60 kg) over 10 min, followed by a 10 min observation period and an identical second dose if AF did not convert to sinus rhythm (SR). Treatment was considered successful if SR occurred within 90 min of starting medication. The conversion rates were 56.4% in patients given flecainide and 50.0% in patients given ibutilide (P=0.34). Multivariate analysis revealed that a lower age for women independently increased the probability of conversion. None of the other variables, including left atrial size, left ventricular systolic function, presence of left ventricular hypertrophy, plasma levels of potassium or magnesium at baseline, or concomitant use of digoxin, beta-blocker, diltiazem or verapamil were predictors of conversion. The frequency of adverse events was comparable in the two treatment groups.
Conclusions: There was no significant difference in the cardioversion efficacy or in the risk of adverse events between flecainide and ibutilide in patients with AF of recent onset. In patients without contraindications to both medications, the physician's choice has to be governed by other factors.