Clinical comparison of ibutilide and propafenone for converting atrial flutter.

Objective: To evaluate the efficacy and safety of intravenous ibutilide and propafenone for immediate treatment of atrial flutter.

Methods: Forty patients with atrial flutter with an arrhythmia duration of three hours to 90 days were randomized to receive up to two 10-minute infusions of ibutilide (1 and 1 mg) or propafenone (70 and 70 mg) with a 10-minute interval.

Results: Ibutilide was superior to propafenone for treating atrial flutter (90% vs. 30%, p < 0.01). The median conversion time in the ibutilide group was 11 min (the 25th and 75th percentile was 10 and 45 min), and the median conversion time in the propafenone group was 35 min (range 20-55 min). In all patients, the duration of arrhythmia before treatment was a predictor of arrhythmia termination, although this was more obvious in the group that received ibutilide. Conversion of atrial flutter by ibutilide was characterized mainly by increased cycle length variability. Bradycardia (2/20) and hypotension (4/20) were more common side effects with propafenone. Of 20 patients given ibutilide, 8 (40%) who developed monomorphic ventricular extrasystoles or repetitive atrial flutter with aberrant conduction tachycardia, no one required any specific treatment except for the interruption of ibutilide infusion.

Conclusion: Ibutilide is highly effective for rapidly terminating atrial flutter. This new class III drug, under monitored conditions, is a potential alternative to currently available cardioversion options.