Verapamil Sensitive Left Ventricular Tachycardia in Three Patients with Prior Myocardial Infarction

Abstract

Background: The efficacy of catheter ablation for Left posterior fascicular ventricular tachycardia associated with myocardial infarction (MI-FVT) has been reported. But the efficacy of verapamil for MI-FVT is unclear. Methods: We evaluated 3 patients with a prior MI who had sustained monomorphic VT showing right bundle branch block morphology (RBBB-MI-VT) and left axis deviation. Lidocaine, amiodarone, procainamide, propranolol, and verapamil were administered for RBBB-MI-VT in all patients. One of them underwent catheter ablation for RBBB-MI-VT. Results: VT was terminated by only a small dose (2.5 mg) of verapamil in all cases but any other agents were not effective. In one case who underwent catheter ablation, clinical VT was induced repeatedly by programmed stimulation. Presystolic purkinje potentials were recorded sequentially along the left ventricular posteroseptal area, where diastolic potentials were recorded partially during VT. Radiofrequency energy was applied at the site in which a Purkinje potential preceded QRS onset by 29 ms during VT and after additional linear ablation across the sites where presystolic purkinje potentials were recorded, clinical VT was successfully eliminated. Conclusions: These findings suggest that the possible pathophysiological mechanism of RBBB-MI-VT may be similar to idiopathic left ventricular tachycardia, which could be eliminated by catheter ablation.