Effects of flecainide on atrial and ventricular stimulation thresholds to repetitive extrasystoles and fibrillation and on "2nd Phase" ventricular arrhythmias in dogs.

Repetitive extrasystole and fibrillation thresholds were assessed by various methods of programmed atrial and ventricular stimulation using intracavitary bipolar electrode catheters and a microcomputer based 3-channel stimulator as previously described. "2nd Phase" ventricular arrhythmias were produced by ligation of the left descending coronary artery. 2,5-Bis-(2,2,2-trifluoroethoxy)-N-(2-piperidylmethyl)benzamide acetate (flecainide, R 818, Tambocor) caused a significant increase of the atrial and ventricular fibrillation thresholds. The antifibrillatory action was similar in atrial and ventricular tissues. "2nd Phase" ventricular arrhythmias were dose-dependently reduced or abolished completely. Similar doses were required to suppress spontaneous arrhythmic activity and to increase the fibrillation thresholds. Thus, flecainide proved to be a powerful antiarrhythmic agent with strong antifibrillatory properties in therapeutic doses. It may be a promising drug for the treatment of atrial and ventricular reentrant arrhythmias.