Verapamil for control of ventricular rate in paroxysmal supraventricular tachycardia and atrial fibrillation or flutter: a double-blind randomized cross-over study.

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.