Double-blind crossover randomized trial of intravenously administered verapamil. Its use for atrial fibrillation and flutter following open heart surgery

Fourteen patients with onset of atrial fibrillation (11) or flutter (three) and ventricular rate over 120 beats per minute following cardiac surgery were treated with intravenous (IV) doses of verapamil hydrochloride or placebo in a double-blind crossover protocol. Patients with poor left ventricular function, hypotension, atrioventricular block, and taking beta-blockers and disopyramide were excluded. The dosages were 0.075 mg/kg and 0.15 mg/kg given 15 minutes apart, with termination of study on achieving an end point (conversion to sinus rhythm or slowing of ventricular rate to below 100 beats per minute). None reached the end point with placebo but all with verapamil. Baseline ventricular rate was 144 +/- 20 beats per minute, after placebo 143 +/- 16 beats per minute, and after verapamil 89 +/- 7 beats per minute (mean +/- SD). Thus, IV verapamil briefly slows the ventricular rate of atrial tachyarrhythmias following cardiac surgery.