Abstract 9628: Association of Electrogram Features and Critical Reentrant Ventricular Tachycardia Sites with Nonischemic Scar on Late Gadolinium Enhanced Cardiac Magnetic Resonance

Abstract

Introductions: The association of local electrogram features with nonischemic scar morphology and distribution on electroanatomic maps (EAM) has not been investigated. We aimed to quantitatively assess the association of nonischemic scar on late-gadolinium enhanced cardiac magnetic resonance (LGE-CMR) with local electrograms and critical sites in patients with nonischemic cardiomyopathy (NICM). Methods: LGE-CMR was performed in 19 patients with NICM. Scar characteristics were classified by scar transmurality and intramural scar types (endocardial, mid-wall, epicardial, patchy, transmural) on LGE-CMR short-axis planes (Figure, upper panel). EAM points were registered to the corresponding LGE-CMR images. Multivariable regression analysis clustered by patient was performed to assess the association of myocardium thickness, scar transmurality and intramural scar types, with electrogram bipolar/unipolar amplitude, duration and deflections. LGE-CMR characteristics of critical ventricular tachycardia (VT) sites were also investigated. Results: In pooled analyses, higher scar transmurality was significantly associated with lower bipolar (Figure, lower panel)and unipolar electrogram amplitude, longer duration and more deflections (P<0.0001). Fractionated and isolated potentials were more likely to be observed in regions with higher scar transmurality (P<0.0001) and patchy scar (vs. endocardial, mid-wall, epicardial scar, P<0.05). Most of the critical sites (16 sites; 89%) were located in scar with >25% scar transmurality. Myocardial wall thickness, scar transmurality and intramural scar types were independently associated with electrogram features on multivariable regression analyses. Conclusions: Electrogram features on endocardial EAM are associated with scar morphology and distribution on LGE-CMR in NICM. This result may optimize procedural strategies including the decision to obtain epicardial access.