Electrophysiologic properties of falipamil (AQA-39)--a new bradycardiac agent.

Falipamil hydrochloride (AQA 39) is a new antiarrhythmic agent structurally related to verapamil. We evaluated the electrophysiologic properties of intravenous falipamil (1.5 mg kg-1 within 20 minutes) in 12 patients. The spontaneous cycle length was significantly (P less than 0.001) prolonged (+79 +/- 59 ms). Atrioventricular conduction was significantly (P less than 0.001) shorter due to AH interval shortening (-17 +/- 14 ms), most probably related to an anticholinergic effect. Similarly, the anterograde Wenckebach point occurred at a significantly (P less than 0.06) higher rate after falipamil (+10 +/- 7 beats min-1). No statistically significant effect was noted on the refractory periods of the AV node, although there was a trend to shortening. The refractoriness of the right atrium and ventricle was significantly prolonged. It is concluded that falipamil is a bradycardiac agent with electrophysiologic properties quite different from those of verapamil and similar to those of class IA antiarrhythmic agents.