ENCAINIDE, a benzanillide derivative, is a new antiarrhythmic agent recently shown to have great efficacy in suppressing ventricular ectopy.` Initial electrophysiologic studies in animals have shown that encainide decreases automaticity, reduces the upstroke velocity and duration of the cardiac action potential and concurrently prolongs the effective refractory period of the action potential.' Subsequent studies have shown that encainide is effective in suppressing atrial and ventricular arrhythmias in a variety of species with varying experimental interventions.2'3