Efficacy of a New Class III Drug Niferidil in Cardioversion of Persistent Atrial Fibrillation and Flutter

AIMS: To study the efficacy and safety of the new class III antiarrhythmic agent niferidil for pharmacological cardioversion in patients with persistent atrial fibrillation (AF) and atrial flutter (AFl). METHODS AND RESULTS: One hundred thirty-four adults (aged 57.8 ± 11 years, 90 males) were included with median AF duration of 3 (1.5-6) months. All patients received a total of 10-30 μg/kg, niferidil, intravenously, in 1-3 (if needed) consecutive boluses at 15-minute intervals. Holter electrocardiogram monitoring was started before infusion and was continued for 24 hours. The criterion for an antiarrhythmic effect was sinus rhythm restoration within 24 hours of the initial bolus. Niferidil converted AF to sinus rhythm in 47.7% of cases after bolus 1, in 62% of cases after bolus 2, and in 84.6% of cases bolus 3. Niferidil induced a 100% recovery rate in patients with AFl and a 91.8% recovery rate in patients with AF of duration from 8 days to 3 months. Nonsustained torsade de pointes occurred in 1 patient (0.7%), and nonsustained monomorphic ventricular tachycardia was observed in 5 patients (3.7%). CONCLUSIONS: The new intravenous class III drug niferidil demonstrated high conversion rates of 84.6% in patients with persistent AF and 100% in patients with persistent AFl. Niferidil may be used as a possible alternative to electrical cardioversion for pharmacological cardioversion of persistent AF/AFl.