[Bepridil--electrophysiologic properties of a new calcium antagonist with an anti-arrhythmia effect].

In 12 patients with recurrent pre-syncope or syncope and suspected sick sinus syndrome, the electrophysiologic properties of bepridil were tested using 1-2 extrastimuli during four basic pacing rates. Bepridil was given in a dose of 5 mg/kg body weight over 10 min. It caused no significant changes in sinus cycle length (+5%) and corrected sinus node recovery time during pacing of 100/min (-6%), 120/min (+8%) and 140/min (+4%). The conduction times PQ- (+10%) and QRS-interval (+6%) increased significantly, AH- (+8%) and HV-interval (+5%) were slightly prolonged. Antegrade Wenckebach point increased from 460 to 508 ms (p less than 0.05). The effective refractory period was prolonged in the atrium (+11%, p less than 0.05), the AV-node (+14%, p less than 0.05) and the right ventricle (6-11% at pacing rates 100-140/min, p less than 0.05 for each cycle length). In relation to the pacing rate, QTc-interval increased highly significantly (p less than 0.01) by 16% (sinus rhythm), 12% (100/min), 20% (120/min) and 19% (140/min). After a mean of 5 min after the start of infusion a doubled T-wave was observed in 11/12 patients, persisting during Holter monitoring for several hours without evidence of increased incidence of spontaneous ventricular arrhythmias. During programmed electrical stimulation with 1-2 extrastimuli, no increase in vulnerability of the right ventricle was obvious in any patient.