Nonischemic cardiomyopathy substrate and ventricular tachycardia in the setting of coronary artery disease

Abstract

Patients with coronary artery disease (CAD) may have ventricular tachycardia (VT) from a separate nonischemic process. Catheter ablation in these patients can be misguided by abnormalities of coronary arteries. To identify (1) the prevalence of unanticipated nonischemic VT in patients with known CAD presenting with VT and (2) the substrate and VT characteristics of this unique subset of patients. We examined consecutive patients referred for VT catheter ablation who had a history of myocardial infarction and angiography documented CAD with presumed ischemic VT. Patients with low-voltage zones and/or VT origin inconsistent with CAD distribution were included for further analysis. Of 732 patients, 9 (1.2%) (7 men; median age 74 years; ejection fraction 30%) fulfilled inclusion criteria. Endocardial left ventricular scar inconsistent with CAD distribution was found in 8 patients. In 1 patient, only epicardial left ventricular scar was found. The distribution of low voltage (<1.5 mV) was predominantly around the aortic and mitral valves. Thirty-one VTs were induced in 8 patients. Most VTs had right bundle branch block (68%); of these VTs, 67% had an R/S transition zone later than lead V4 consistent with basal VT origin. Epicardial ablation was necessary in 2 patients. During follow-up (30 [25-39] months), 7 of 9 patients (78%) were free of recurrent VT. A small but important subgroup of patients with CAD and VT has a nonischemic substrate/etiology for VT. The presence of multiple VTs with basal origin suggests a potential nonischemic perivalvular substrate and possible need for epicardial VT ablation.