B-PO05-181 HIS BUNDLE PACING PRODUCES MORE PHYSIOLOGICAL VENTRICULAR REPOLARISATION THAN BIVENTRICULAR PACING IN HEART FAILURE WITH LEFT BUNDLE BRANCH BLOCK

Abstract

Biventricular pacing (BVP) shortens left ventricular activation time (LVAT) in patients with heart failure and left bundle branch block (LBBB). His bundle pacing can correct LBBB (HBP-CRT). The effects of BVP and HBP-CRT on ventricular repolarisation are not known. To measure the effects of HBP-CRT and BVP on LV repolarisation using non-invasive epicardial mapping (ECGI). Participants were recruited in 2 groups. 1) Patients scheduled for BVP for heart failure with LBBB, 2) Individuals with normal QRS and LV function. We defined HBP-CRT as LVAT shortening >10ms. We compared the effects of HBP-CRT and BVP on ECGI-derived dispersion of repolarisation and activation-recovery intervals. 21 HBP-CRT and 21 narrow intrinsic QRS were recruited. LV repolarisation dispersion was reduced by HBP-CRT (-42.0ms, 95%CI: -52.3 to -31.7, p <0.001) but not BVP (11.9ms, -6.2 to 30.1, p=0.182, 18.5ms). Change in LV repolarisation dispersion from BVP to HBP-CRT was -56.5ms (-70.5 to 42.5, p<0.001). LV repolarisation dispersion with HBP-CRT was not different from narrow intrinsic QRS (2.8ms, -16.2 to 21.7, p=0.981). Reduction in LV repolarisation dispersion with HBP-CRT from intrinsic LBBB was similar to LVAT shortening (-45.9ms, 95%CI: -59.3 to -32.4). However, LV activation-recovery interval dispersion was also reduced by HBP-CRT (-56.5 ms, -70.5 to -42.5ms, p<0.001). HBP-CRT can normalise repolarisation dispersion, producing more physiological repolarisation than BVP. This occurs through effects on both activation and action-potential duration. HBP-CRT may prevent ventricular arrhythmias in heart failure with LBBB to a greater extent than BVP.