Enhanced antiarrhythmic efficacy of propafenone when used in combination with procainamide or quinidine

This study evaluated the efficacy and safety of combining propafenone with procainamide or quinidine for treating ventricular arrhythmias in patients in whom procainamide or quinidine therapy alone failed to suppress arrhythmias. In 30 patients, the addition of propafenone resulted in a significant reduction of premature ventricular contraction (PVC) frequency compared to drug-free baseline (406 PVC/hr vs 33, p < 0.001) and to procainamide or quinidine monotherapy (211 PVC/hr vs 27, p < 0.01). Propafenone alone was also more effective than either procainamide or quinidine and resulted in significant suppression of PVC compared to the drug-free state (406 PVC/hr vs 38, p < 0.001). However, higher propafenone doses were necessary during monotherapy as compared to propafenone therapy combined with procainamide or quinidine (730 mg/day vs 480 mg/day, p < 0.001). Of the 30 patients, 22 required an increase in propafenone dose during monotherapy as compared to combination therapy. Thus, propafenone is an effective antiarrhythmic agent when used in combination with type IA antiarrhythmic drugs. With these combinations, lower doses of propafenone can be utilized effectively than with propafenone alone.