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

Abstract

Background: 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.

Objective: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Ablation; CAD; Coronary disease; EGM; ICD; LBBB; LV; LVOT; MI; MRI; Mapping; NICM; Nonischemic; RBBB; RV; VT; Ventricular tachycardia; coronary artery disease; electrogram; implantable cardioverter-defibrillator; left bundle branch block; left ventricle outflow tract; left ventricle/ventricular; magnetic resonance imaging; myocardial infarction; nonischemic cardiomyopathy; right bundle branch block; right ventricle/ventricular; ventricular tachycardia.