Verapamil for Control of Ventricular Rate in Paroxysmal Supraventricular Tachycardia and Atrial Fibrillation or Flutter

The effectiveness of verapamil in controlling ventricular rate was evaluated in 20 patients with atrial fibrillation or flutter with a rapid ventricular response (Group 1) and 30 patients with paroxysmal supraventricular tachycardia (Group 2). In Group 1 low-dose verapamil (0.075 mg/kg body weight) decreased the mean ventricular rate from 146 to 114 beats/min (p < 0.01) compared to a decrease of 145 to 132 beats/min (p < 0.01) after placebo. In Group 2, 14 of 29 patients converted to sinus rhythm after low-dose verapamil, nine of 15 after high-dose verapamil (0.15 mg/kg body weight), and one of 24 after placebo (p < 0.01). We conclude that verapamil results in a clinically significant slowing of the ventricular response in atrial fibrillation or atrial flutter and is superior to placebo for conversion of paroxysmal supraventricular tachycardia to sinus rhythm.