Po-03-009 3830 lead tip position on computed tomography and electrophysiologic outcomes in left bundle branch area pacing

Prior studies have evaluated the impact of lead tip distance from the LV blood pool on pacing parameters during left bundle branch area pacing (LBBAP). Few studies to date have evaluated lead tip angulation within the interventricular septum (IVS) in relation to pacing morphology on surface 12-lead ECG. To establish the observed lead tip trajectories within the interventricular septum encountered during LBBAP. Patients who underwent LBBAP implantation between 02/2019-07/2022 were retrospectively analyzed. Patients who underwent computed tomography (CT) of the chest or thorax post-implantation for any indication were included for analysis. Lead distance from the mitral annulus, lead tip distance from LV blood pool (DEBP), lead tip angle of incidence (AOI), and post-implantation electrocardiographic and pacing parameters were analyzed (Figure 1a). 38 pts were identified, out of whom 37 pts had CT images available for analysis. In the 20 pts with contrast enhanced imaging, DEBP was 2.1±1.8mm. Average observed AOI was 10.9±20.6 degrees in the axial plane (long axis; Figure 1b) and 12.4±22.2 degrees in the saggital plane (short axis; Figure 1c). Lead impedance at time of implant did not correlate strongly with axial or sagittal angle of incidence (R2=0.01 and 0.03 respectively) or with distance from LV endocardial blood pool (R2=0.04). The most commonly encountered lead insertion locations included the mid-septal (22, 59.5%), basal septal (4, 10.8%), and mid antero-septal (3, 8.1%) positions (Figure 1d). Average lead tip distance from the AV annulus was 36.6±8.2mm. Mean paced QRSd for the basal, mid, and apical cohorts were 122.5±8.1ms, 118.5±10.7ms, and 120±15.9ms, respectively. Left ventricular activation time in lead V6 numerically decreased for more apical positions, with basal, mid and apical values of 84.4±11.9ms, 73.9±10.6ms, and 69.5±6.0ms, respectively. Lead threshold, impedance, and sensed R waves were stable at time of 2 year follow-up. No analyzed patients underwent lead revision. Multiple lead tip orientations are observed in relation to the IVS during successful LBBAP. More apical lead tip positioning may result in numerically lower LVAT values, despite similar overall QRS duration.