The aim of this study was to investigate efficacy and safety of bepridil (a multi-channel blocker including several K channels) for conversion of long lasting atrial fibrillation (AF)-^sMethods and Results: We studied 30 consecutive patients (22 men, mean age of 61 +- 8 years) with AF lasting 3 months or more. Patients received bepridil (200 mg/day) for 2 to 4 weeks. When sinus rhythm was not restored with bepridil and QT interval prolongation was not marked (QTc <0.50 sec and %increase<25% of the baseline value), oral aprindine (40 or 60 mg/day) was added to bepridil. Past Fourier transform analysis (20 consecutive 4096-msec epochs with 50% overlap) was performed using lead Vl before and after bepridil administration. Fibrillation cycle length (FCL) was calculated from the peak frequency of each epoch. Sinus rhythm was restored in 20 patients (67%) 27 days (7 to 49 days) after bepridil had been started. Eleven of 20 responders received only bepridil and the remaining 9 responders received additional aprindine. Responders had a greater increase in FCL by bepridil than non-responders (% increase: 33 +- 10 % vs. 17 +- 5 %, p<0.001). The duration of AF was shorter in responders than in non-responders (19 +- 24 months vs. 118 +- 74 months, p<0.001). After conversion to sinus rhythm 7 patients required reduction of bepridil dosage because of QTc >0.50 sec in 5, frequent premature ventricular contractions in 1 and junctional rhythm in 1. Conclusions: Bepridil alone and in combination with aprindine are effective and safe for termination of long-lasting persistent AF. Increase in FCL by bepridil and duration of AF may be useful predictors for successful conversion to sinus rhythm.
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