Verapamil-sensitive left ventricular tachycardia in patients with coronary artery disease: clinical and electrophysiologic features consistent with triggered activity.

This is a retrospective review of three male patients with verapamil-sensitive left ventricular tachycardia, severe coronary artery disease, and past myocardial infarction. Each patient had severe left ventricular dysfunction (mean ejection fraction 34%). Each tachycardia had a right bundle branch block/left axis deviation morphology, which was sustained with isoproterenol. One patient had incessant tachycardia 3 days after coronary bypass surgery. Electrophysiology and clinical parameters were suggestive of triggered activity rather than reentry. Each tachycardia was terminated with verapamil but failed with adenosine, beta blockers, and class I/III antiarrhythmics. Prior cases of verapamil-sensitive ventricular tachycardia have been seen in patients without organic heart disease, and the putative mechanism appears to be reentry. These patients with ischemic coronary artery disease may exhibit a mechanism of triggered activity in the Purkinje system region, which is responsive to calcium channel blockade. Successful radiofrequency ablation was guided by Purkinje potentials.