Evaluation of the Effect of Bepridil on Paroxysmal Atrial Fibrillation. Relationship Between Efficacy and the f-f Interval in Surface ECG Recordings.

Bepridil, a multi-ion channel blocker, is effective for some types of cardiac arrhythmias, and so its effect on the paroxysmal atrial fibrillation (PAF) was evaluated in the present study, comparing it with class Ic antiarrhythmic drugs. The relationship between efficacy and the f-f interval in the surface ECG recording was also analyzed. Sixty-one symptomatic PAF patients were randomized to a bepridil group (200 mg/day, n=23) or class Ic drug group (flecainide 100-200 mg/day or pilsicainide 75-150 mg/day, n=38). The drug was considered effective for PAF prevention when symptomatic episodes of PAF were decreased to less than 50% during the follow-up period of 2-6 months. The f-f interval in the surface 12-lead ECG trace was evaluated during a PAF episode. Both bepridil and the class Ic drugs were effectively prevented PAF (15/23 (65.2%) vs 24/38 (63.1%) patients, NS). In the class Ic drug group, the f-f interval was longer in the effective cases (114+/-48 ms) than in the non-effective cases (68+/-26 ms, p=0.0002). In contrast, in the bepridil group the f-f interval was shorter in the effective cases (85+/-26 ms) than in the non-effective ones (152+/-45 ms, p=0.0005). When comparing the non-effective cases in the 2 groups, the bepridil group showed a significantly longer f-f interval than the class Ic drug group (p=0.0003). As a result of drug administration, the class Ic drugs prolonged the f-f interval from 78+/-33 ms to 128+/-46 ms (p=0.0004) whereas bepridil showed no change (109+/-39 ms vs 135+/-47 ms). For clinical PAF prevention, the effect of bepridil matched that of class Ic antiarrhythmic drugs. Because bepridil was effective in PAF patients with relatively shorter f-f intervals without prolonging the f-f interval, bepridil is considered to work mainly as a class III antiarrhythmic drug.