PO-01-182 CONDUCTION SYSTEM PACING REMAINS EFFECTIVE IN PATIENTS WITH NON-CONDUCTIVE SEPTAL SCAR BUT SURVIVING PURKINJE

Abstract

Conduction system pacing (CSP), delivered through His bundle (HBP) or left bundle pacing (LBP), is a novel effective treatment for patients with proximal left bundle branch block (LBBB). The presence of septal scar is known to affect response to CSP, but the effect of scar conduction properties on response to CSP has never been investigated. To quantify the effect of scarred myocardium and Purkinje conduction velocity (CV) on response to CSP using computational modelling. We computed ventricular activation on 24 four-chamber heart geometries generated from heart failure patients, inclusive of septal scar and His-Purkinje networks with proximal LBBB. We simulated LBBB baseline, selective HBP and selective LBP with optimized atrioventricular delay (AVD) with the following myocardium and Purkinje conduction properties within the scar: A) non-conductive myocardium and Purkinje; B) slow conductive myocardium and Purkinje (10% CV compared to healthy tissue); C) non-conductive myocardium and slow conductive Purkinje. Response was quantified with 90% biventricular (BIVAT90) and 95% left ventricular (LV) activation times. HBP and LBP were ineffective in the presence of non-conductive septal myocardium and Purkinje (LVAT95: baseline 130.9±11.2ms vs HBP 129.4±13.9ms vs LBP: 130.2±11.6, P=0.9, Fig A,D). CSP reduced BIVAT90 and LVAT95 compared to baseline when the myocardium and the Purkinje within the scar were slow but conductive (BIVAT90: baseline 120.7±9.5ms, HBP: 98.1±11.2ms, LBP: 82.9±9.4ms, P<0.01 vs baseline, Fig B,D). CSP remained effective when the scarred myocardium was non-conductive and the Purkinje was slow but conductive (BIVAT90: baseline 115.7±11.2ms, HBP: 84.4±7.6ms, LBP: 64.3±8.6ms, P<0.01 vs baseline, Fig C,D). The presence of septal scar does not necessarily make CSP ineffective. CSP remains effective in patients with LBBB and septal scar if the Purkinje within the scar is still conductive.