Oral verapamil fails to prevent supraventricular tachycardia following coronary artery surgery.

A prospective randomised trial was performed on 100 patients undergoing coronary artery bypass grafting without concomitant procedure. The study group commenced oral verapamil 40 mg three times daily on the first post-operative day while the control group received no antiarrhythmic agents. The pre-operative characteristics of both groups were similar with the exception of the incidence of hyperlipidemia which was greater in the verapamil group (P = 0.04). Myocardial protection was achieved with cold crystalloid cardioplegia. Cardiopulmonary bypass times, aortic cross clamp times and graft numbers were similar for both groups. Nine patients were excluded on the first post-operative day; the remainder were studied for 8 days. Supraventricular tachyarrhythmias (atrial fibrillation, atrial flutter or paroxysmal supraventricular tachycardia) were detected in 8 patients in the study group (n = 44) and in 5 patients in the control group (n = 47). The difference was not significant (P = 0.3). The ventricular rate in patients taking verapamil who developed supraventricular tachycardia was 138 +/- 14.9 compared with 156.8 +/- 17.9 in the control group, but the difference failed to reach significant levels (P = 0.065). In conclusion, prophylactic oral verapamil 40 mg given three times daily after coronary artery surgery failed to decrease the incidence of post-operative supraventricular tachycardia or to significantly influence the ventricular rate if tachycardia developed.