Bepridil Prevents Paroxysmal Atrial Fibrillation by a Class III Antiarrhythmic Drug Effect

BACKGROUND: [corrected] Bepridil, a multiple ion-channel blocker, has been reported to prevent paroxysmal atrial fibrillation (PAF). The f-f interval of PAF during treatment with bepridil versus class Ic antiarrhythmic drugs was compared. METHODS: Fifty-two patients with PAF were randomized to bepridil, 200 mg/day (n = 14) versus flecainide, 100 to 200 mg/day (n = 15) or pilsicainide, 75 to 150 mg/day (n = 23). The drug was considered effective when symptomatic episodes of PAF were decreased to < 50% during a follow-up of 2 to 6 months. The f-f interval was measured in 12-lead ECGs of initial PAF episodes. RESULTS: Bepridil and Ic were effective in 10 of 14 (71.4%) and 24 of 38 patients (63.2%), respectively (ns). In the Ic group, the f-f interval was longer in successfully (114 +/- 48 ms) than in unsuccessfully (68 +/- 25 ms) treated patients (P = 0.002). In the bepridil group, the f-f interval was shorter in successfully (84 +/- 27 ms) than unsuccessfully (155 +/- 68 ms) treated patients (P = 0.015). When comparing unsuccessfully treated patients, the f-f interval in the bepridil group was significantly longer than in the Ic group (P = 0.007). CONCLUSIONS: Bepridil was as effective as Ic drugs in the prevention of PAF. Because it was more effective in smaller (functional) than larger (anatomical) reentrant circuits, the effect of bepridil was considered to be mainly attributable to a class III antiarrhythmic action.