a b s t r a c tThe aim of this study was to evaluate the clinical significance of serum bepridil (Bep) concentration (SBC) for safely managing patients with atrial tachyarrhythmias (AT). Methods and results: SBC was measured in 37 patients with AT, including atrial fribrillation (AF) (31 cases), AF þ atrial flutter (AFL) (4 cases), AFL (1 case), and atrial tachycardia (1 case). The patients were administrated Bep for more than 4 weeks at the same dose. SBC was positively correlated with Bep dose per kilogram of body weight (p ¼0.015), QT interval (p¼ 0.019), and QTc (p ¼0.034). The patients were divided into 2 groups according to their SBC: the high-SBC (HSBC) group of 8 patients with an SBC Z 500 ng/ml and a low-SBC (LSBC) group of 29 patients with an SBC o 500 ng/ml. There was no difference in maintenance of sinus rhythm between the groups. For clinical variables, QT and QTc were significantly longer in the HSBC than in the LSBC group (p¼ 0.004 and p ¼ 0.016, respectively). Patients with QT 40.5 were more prominent in the HSBC group (37.5% vs. 3.4%, p¼ 0.026), and torsade de points (TdP) occurred in only one patient in the HSBC group. However, there were several patients with normal QT/QTc despite having high SBC. Conclusions: In patients treated with Bep, measurement of SBC is useful for preventing proarrhythmias.
Introduction: Bepridil is a multi-ion channel blocker similar to amiodarone. Recent clinical studies have indicated that bepridil shows a favorable efficacy for the treatment of atrial fibrillation (AF). The purpose of this study is to evaluate the effectiveness of bepridil for electrical remodeling induced by rapid atrial stimulation particularly in the acute-phase.Methods and Results: We studied 18 pigs subjected to right atrial appendage rapid pacing at 500 beats/min for 3 hours that were randomly assigned to the absence or presence of bepridil administration for 14 days. They were divided into 2 groups, an atrial pacing only group (PG; n ¼ 10) and an atrial pacing plus bepridil group (PBG; n ¼ 8). We measured the effective refractory period (ERP) at the right atrial free wall (RAFW), the right atrial appendage (RAA) and the left atrial free wall (LAFW), as well as the monophasic action potential duration at 90% (MAPD 90 ) in RAA during the rapid pacing phase and recovery phase.In the PG, the ERP decreased gradually at all atrial sites during the 3 hour phase of rapid pacing. In contrast, the shortening of the ERP was suppressed significantly at the RAFW and LAFW in the PBG. The MAPD 90 was also shortened by rapid atrial pacing in the PG. This shortening was suppressed significantly in the PBG.We evaluated the effect of bepridil on the inducibility of AF during all time spans. The mean number of AF occurrences in the PBG was significantly fewer than in the PG.(2:1 AE 2:4 vs. 8:5 AE 7:0, p < 0:05)Conclusions: Bepridil prevented the shortening of the ERP and MAPD 90 induced by rapid atrial pacing in the acute phase. The results of this study might explain the efficacy of bepridil for preventing the recurrence of paroxysmal AF. (J Arrhythmia 2009; 25: 89-94)
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