B-PO03-023 HIS BUNDLE PACING ACHIEVES BETTER VENTRICULAR SYNCHRONY THAN BIVENTRICULAR PACING IN PATIENTS WITH SCAR IN THE LEFT VENTRICULAR FREE WALL

Abstract

His bundle pacing (HBP) is a novel pacing strategy for cardiac resynchronization therapy (CRT). HBP has been associated with improved response compared to conventional CRT and biventricular endocardial (BIV-endo) pacing. The effect of HBP in patients with scar has however not yet been studied. To investigate differences in response between HBP and BIV-endo pacing in patients with scar in the left ventricular (LV) free wall. We computed ventricular activation on 24 four-chamber heart meshes with Purkinje networks exhibiting left bundle branch block (LBBB). We mapped a LV free wall scar and border zone geometry from a pre-existing LV mesh [Fig A]. HBP and BIV-endo pacing were simulated in the presence and in the absence of scar. Response from baseline was quantified with LV 95% activation time (LV-AT 95) and biventricular dyssynchronous index (BIV-DI), computed as the standard deviation of ventricular activation times. BIV-DI was significantly reduced during HBP compared to BIV-endo pacing both in the presence (-13±2ms vs -15±2ms, p<0.05) and in the absence (-9±2 ms vs -11±2ms, p<0.05) of scar in the LV lateral wall [Fig B]. LV-AT 95 was also significantly shorter during HBP compared to BIV-endo pacing (scar: -31±8ms vs -54±9ms, p<0.05; no scar: -22±7ms vs -44±7ms, p<0.05) [Fig C]. HBP restores native synchronous activation by recruiting the viable fast-conducting Purkinje system. LBBB patients with lateral scar therefore experience better ventricular resynchronization using HBP compared to BIV-endo pacing.