Procainamide, Quinidine, Disopyramide, Cibenzoline, Pirmenol — Efficacy in the Treatment of Ventricular Arrhythmias: Current Status and Controversies

In the review of the Type IA antiarrhythmic drugs, I will focus on the present knowledge regarding relative efficacy and toxicity in treating ventricular rhythm disturbances, and highlight a few areas of recent investigational interest including the antiarrhythmic efficacy of NAPA, bioavailability of sustained release preparations, as well as the issue of “proarrhythmia” with this group of medications. The assets and liabilities of the present classification system of antiarrhythmic agents has already been reviewed in this symposium. Suffice it to say that these drugs share certain electrophysiologic properties including their ability to decrease dV/dT of phase 0, producing conduction slowing, prolonging action potential duration and refractoriness, depressing membrane excitability, membrane responsiveness, and automaticity in normal Purkinje fibers.1 The current status of cibenzoline and pirmenol, two investigational agents for the treatment of ventricular rhythm disturbances, are also reviewed. Both these drugs share many electrophysiologic properties with the Type IA drugs.