Treatment of atrial arrhythmias. Effectiveness of verapamil when preceded by calcium infusion.

Intravenous verapamil hydrochloride was used alone in 63 episodes of atrial fibrillation and flutter and six episodes of supraventricular tachycardia (SVT) (group A). Calcium chloride was given intravenously prior to verapamil in 41 episodes of fibrillation and flutter and 18 episodes of SVT (group B). All patients with SVT converted to normal sinus rhythm, with eight in group B converting after administration of calcium alone. Therapy lowered the heart rate in all patients with fibrillation and flutter; however, those given verapamil alone had a mean decrease in systolic pressure of 18.8 mm Hg; there was no change in those pretreated with calcium. The mean dose of verapamil required by group B was significantly lower than in group A. Many with atrial fibrillation or flutter who received digoxin subsequently converted to sinus rhythm. Thus, pretreatment with calcium decreased the hypotensive effect of verapamil without compromising its antiarrhythmic effect.