Efficacy of oral propafenone in chronic ventricular arrhythmias: a placebo controlled cross-over exercise study.

The efficacy of propafenone, a new class I C antiarrhythmic drug, on ventricular premature contractions (VPCs) during rest and exercise was assessed during a two-phase protocol: phase 1, an initial two week placebo controlled double blind cross-over assessment; phase 2, an open 3 month follow-up. Twelve consecutive patients with symptomatic chronic ventricular arrhythmias and fulfilling other inclusion criteria underwent an exercise test and were allocated to either propafenone or placebo. During the double blind phase, oral propafenone significantly reduced the number of VPCs at rest with the patient supine or sitting, during the bicycle ergometer test, and after the exercise test. After 3 months of treatment a 90 to 100% reduction of VPCs was achieved in 11 patients continuing on 600 to 900 mg of propafenone daily. Treatment was stopped in one patient during the double blind phase because of drug induced LBBB. A prolongation of the PR interval and QRS duration occurred in all patients with propafenone doses exceeding 450 mg day-1. Subjective side effects were slight and consisted of abnormal taste sensations and minor central nervous symptoms. The results suggest that propafenone is an effective drug for the treatment of ventricular arrhythmias in selected patients. A-V or intraventricular conduction disturbances contraindicate its use.