Sinus Rhythm QRS Amplitude and Fractionation in Patients with Non-Ischemic Cardiomyopathy to Identify Ventricular Tachycardia Substrate and Location.

Abstract Background Ventricular tachycardia (VT) substrate in left ventricular (LV) nonischemic cardiomyopathy (NICM) consists of fibrosis with surviving myocardium. Objective: To determine if, in patients with LV NICM and sustained VT, reduced QRS amplitude and QRSf during sinus rhythm can identify the presence and location of abnormal S-NICM and/or FW-NICM VT substrate. Methods We compared patients with NICM and VT (Group 1) with electroanatomic mapping septal (S-NICM, n=21) or free wall (FW-NICM, n=20) VT substrate to a 38 patient reference cohort (Group 2) with cardiac MRI (cMRI) and NICM but no VT referred for primary prevention ICD, 26 (68.4%) with late gadolinium enhancement (LGE). Results Group 1 had lower QRS amplitude in leads II (0.60±0.22 vs 0.86±0.35, p Conclusions In LV NICM, low frontal plane QRS (