Sex differences outcomes in conduction system pacing for patients with typical left bundle branch block

Background: Biventricular pacing (BVP) appears to confer more pronounced advantages in women, yet the impact of conduction system pacing (CSP) remains insufficiently characterized. This investigation seeks to elucidate sexspecific disparities in clinical outcomes among patients with typical left bundle branch block (LBBB) undergoing CSP, with a particular focus on assessing contributory factors. Methods: Consecutive patients diagnosed with nonischemic cardiomyopathy, exhibiting left ventricular ejection fraction (LVEF) <= 40%, and manifesting typical LBBB as Strauss criteria, underwent CSP. Subsequent longitudinal monitoring assessed improvements in LVEF and the composite endpoint of mortality or heart failure hospitalization (HFH). Results: Among the included 176 patients, women (n = 84, mean age: 69.5 f 8.8 years) displayed smaller heart size (LVEDd, 62.0 f 8.3 mm vs. 64.8 f 7.9 mm, P = 0.023) and shorter baseline QRSd (163.5 f 17.7 ms vs. 169.7 f 15.1 ms; P = 0.013) than men. Of the 171 patients who completed the follow-up, super-response was observed in 120 (70%), with a higher occurrence in women than men (78.3% vs. 62.5%, P = 0.024). The incidence of death or HFH was numerically lower in women (7.1% Vs 13%, Log-rank P = 0.216). Notably, the super-response showed a significant difference in women compared to men at the same electrocardiography and/ or echocardiographic parameters value. Mediation analysis between sex and super-response revealed that LVEDd and pQRSd play an intermediary role, with the mediation proportion of 26.07% and 27.98%, respectively. Conclusions: Women may derive more benefits from CSP, and pQRSd and LVEDd partly drive this difference.