Endo-Epicardial Electrical Disarray in Arrhythmogenic Cardiomyopathy with Ventricular Arrhythmias

Abstract

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is a hereditary condition frequently presenting with ventricular arrhythmias (VA). VA burden may be disproportionate to detectable structural alterations. OBJECTIVE(S): To quantify local disorganisation of electrical propagation using the Vector Field Heterogeneity (VFH) metric in patients with ACM and to assess whether VFH may unmask sub-clinical substrate missed in conventional voltage maps. METHOD(S): High-density endo-epicardial substrate maps acquired with a 16-pole grid catheter in patients with ACM were retrospectively reviewed. Directional vector maps of electrical propagation were computed offline from 4x4 unipolar arrays. VFH, ranging from 0 (perfect planar wave) to 1 (maximal disorganisation), was estimated as a quantitative measure of local propagation heterogeneity. VFH values were compared between endo- and epicardial maps and across omnipolar voltage (OV)-defined regions: normal (OV>1.5mV), border zone (0.3mV-1.5mV), scar (<0.3mV), as well as isochronal deceleration zones (DZ). RESULT(S): 23 patients were included. VFH differed significantly across voltage categories (p<0.001) with highest VFH observed in regions OV<0.3mV (epi 0.57 0.28] vs. endo 0.56 0.30]). In border zone regions, epicardial VFH exceeded endocardial (0.41 0.42] vs 0.39 0.45]), whereas in normal OV areas, endocardial VFH was higher than epicardial (epi 0.17 0.27] vs. endo 0.29 0.34]). Highest VFH were recorded at sites of DZs (0.59 0.25]), with a trend towards increased electrical disarray during sensed extras (0.62 0.28], p=ns). Notably, in epicardial regions with normal voltage directly adjacent to low-voltage substrate, VFH was significantly elevated compared to overall normal voltage areas (0.26 0.32] vs.0.17 0.27], p<0.001). CONCLUSION(S): Heterogeneous electrical propagation quantified by VFH is significantly increased in patients with ACM at sites of scar and DZs, but also in normal voltage areas adjacent to low-voltage areas and on the endocardium. This could indicate microstructural alterations and/or transmural disease progression that are missed in traditional assessments but unmasked by VFH and could complement existing substrate mapping approaches in ACM.Copyright © 2025. Published by Elsevier Inc.