Adenosine versus verapamil in the treatment of supraventricular tachycardia: a randomized double-crossover trial.

The safety and efficacy of verapamil and adenosine in the acute termination of supraventricular tachycardia were compared in a randomized double-crossover trial. Of 32 eligible patients with either spontaneous or induced narrow complex tachycardia, seven (22%) patients experienced conversion to sinus rhythm with carotid sinus massage. The other 25 patients were randomly assigned to receive either adenosine (n = 14) or verapamil (n = 11). Relative drug efficacies were 100% for adenosine versus 73% for verapamil, p = NS. Adenosine given at less than or equal to 120 micrograms/kg caused conversion in 12 (86%) of 14 patients. The other two patients required 20 mg adenosine for conversion. After conversion the systolic blood pressure increased significantly in the adenosine group but not in the verapamil group. Reinitiation of tachycardia occurred in two (14%) of 14 patients randomized to the adenosine group. Serious adverse hemodynamic effects were observed in one (9%) of 11 patients randomized to verapamil. The incidence of conversion arrhythmias was similar in both treatment groups (adenosine 57%, verapamil 50%, p = NS).