Therapy with Disopyramide Phosphate

Disopyramide phosphate was administered intravenously to 57 patients with 60 episodes of arrhythmia (21 supraventricular and 39 ventricular) as a 2 mg/kg bolus. Conversion to sinus rhythm was achieved in three (38 percent) of eight patients with atrial flutter, two (20 percent) of ten patients with atrial fibrillation, one (33 percent) of three patients with paroxysmal atrial tachycardia, and two (50 percent) of four patients with sustained ventricular tachycardin. In nine (75 percent) of 12 patients with nonsustained ventricular tachycardia, suppression of the arrhythmia was accomplished following the intravenous bolus of disopyramide. In 18 (78 percent) of 23 patients with frequent ventricular premature contractions, greater than 50 percent suppression of the ventricular premature contractions was achieved. These effects were satisfactorily maintained in six (86 percent) of seven patients with nonsustained ventricular tachy‘J’he currently used orally administered drugs in the United States for treatment of cardiac arrhythmias include quinidine, procainamide hydrochloride, digitalis, diphenylhydantoin, and propranolol. These drugs have proved successful, individually or in various combinations, in many clinical circumstances; however, short-term and long-term toxicity of each of these agents and the lack of any consistent beneficial effect in many cases remain of major concern. Lidocaine, the principal parenterally used antiarrhythmic agent, although comparatively less toxic, is not suitable for ambulatory patients.