Electrophysiologic and antiarrhythmic actions of bepridil. Comparison with verapamil and ajmaline for atrioventricular reentrant tachycardia.

Bepridil (2 mg/kg intravenously) was given to 20 patients with atrioventricular (AV) reentrant tachycardia and its effects were compared with those of verapamil (0.15 mg/kg intravenously) in 8 patients and ajmaline (0.75 mg/kg intravenously) in 12. After baseline electrophysiologic measurements, the drugs were given during sustained AV reentrant tachycardia (8 patients had dual AV nodal pathways and 12 had an accessory AV pathway). Verapamil terminated AV reentrant tachycardia in 7 patients and bepridil terminated it in 6. In 8 of the patients who received ajmaline, AV reentrant tachycardia was terminated and in 6 of this group bepridil did so. Bepridil was more successful in terminating AV reentrant tachycardia in those with dual AV nodal pathways than in those with an accessory AV pathway. Bepridil slowed sinus rate by 10% (p less than 0.0001), whereas verapamil did not change it significantly. Both verapamil and bepridil administration prolonged AV nodal conduction (39% and 44%, respectively), lengthened AV nodal effective refractory period (18% and 17% respectively) and increased the Wenckebach cycle length of the AV node (24% and 25%, respectively) to a significant degree (p less than 0.05). Bepridil also lengthened atrial and ventricular effective refractory periods (p less than 0.01) and QT interval (p less than 0.0001) in the group as a whole; in those receiving ajmaline and bepridil only atrial refractoriness was significantly altered (p less than 0.05). After treatment for 3 to 5 days with oral bepridil, 19 patients underwent repeat study.(ABSTRACT TRUNCATED AT 250 WORDS)