Sex differences in electrophysiological characteristics of left bundle branch area pacing

Abstract Background Conduction system pacing (CSP) with left bundle branch area pacing (LBBAP) is a novel and promising technique for pacemaker implantation. However, sex differences in the electrophysiological characteristics of LBBAP and its potential impact on CSP criteria have not yet been thoroughly studied. Purpose To assess sex differences in the electrophysiological characteristics of LBBAP. Methods We prospectively included 218 consecutive patients, undergoing LBBAP at a tertiary center between April 2022 and October 2024, into our CSP registry. LBBAP capture types included proximal left bundle pacing (LBP), left bundle fascicular pacing (LBFP), and left ventricular septal pacing (LVSP). Intracardiac electrograms and surface electrograms were recorded at a speed of 100 mm/s. We compared sex differences in pre- and intraprocedural electrophysiological parameters. Results Overall, median age was 76 (IQR 68-82) years, and 62 (28%) patients were female. The three most frequent indications for pacemaker implantation were high-grade AV block (68%), sick-sinus syndrome (6.5%) and atrial fibrillation (4.6%). Compared to men, female patients undergoing LBBAP were older (80 vs. 75 years, p=0.011) and had a lower BMI (25.2 vs. 26.7 kg/m2, p=0.041). There was no sex difference in pacemaker indications, comorbidities, or procedural length (Figure). In the preprocedural ECG, women had shorter QRS durations than men (104 vs. 127 ms, p <0.001). After lead placement, the distribution of different LBBAP capture types was similar between sexes. However, women had a shorter paced QRS duration than men (112 vs. 119 ms, p=0.016) and a shorter V6 R-wave peak time (V6RWPT) (70 vs. 80 ms, p=0.002), but similar V6-V1 interpeak interval (25 vs. 30 ms, p=0.7). There were no differences in ventricular sensing (10.3 vs. 10.0 mV, p=0.4), bipolar threshold (0.85 vs 0.80 V, p=0.7), and bipolar impedance (767 vs. 741 Ohm, p=0.4). Conclusion In patients undergoing LBBAP, women had shorter paced QRS durations and V6RWPT compared to men. Our findings indicate a faster left ventricular activation with LBBAP in women and suggest, that electrophysiological criteria for CSP may need to be different in women compared to men.Graphical Abstract