Sinus arrest caused by atenolol-verapamil combination.

A case on concomitant atenolol-verapamil therapy for hypertension and angina pectoris, developing sinus arrest and life-threatening bradycardia is described. The complication occurred with low doses of both the agents and normal electrophysiologic status of the heart. The example suggests that pharmacodynamic synergism contributes more than pharmacokinetic interaction causing adverse reactions during beta blocker-verapamil therapy.