Quantitative analysis reveals influencing factors to facilitate successful anodal-ring capture in left bundle branch pacing

AIMS: Left bundle branch pacing (LBBP) maintains left ventricular synchrony but induces right ventricular conduction delay (RVCD). Although anodal-ring capture (ARC) during bipolar LBBP improves RVCD, it is not achieved in all patients receiving LBBP. This study aimed to analyze the factors influencing ARC implementation. METHODS AND RESULTS: Patients receiving LBBP with intraoperative ARC testing were enrolled. Electrocardiographic parameters were measured, including stimulus-to-QRS duration (stim-QRSd), stimulus-to-left/right ventricular activation time (stim-LVAT/RVAT), and V(6)-V(1) interpeak interval. The distribution of lead-tip sites was described as the corrected longitudinal and lateral distance (longit-/lat-dist). Relative angles of the LBBP lead were measured. Echocardiography in short-axis view was used to measure the intraseptal lead length. Intergroup comparisons, correlation analysis, and stepwise logistic regression were performed. In total, 105 patients were included, among which 65 (62%) patients achieved ARC at a pacing output ≤ 5.0 V/0.5 ms (average 3.1 V/0.5 ms). Anodal-ring capture further shortened the stim-QRSd by 13.1 ± 7.5 ms. Better unipolar-ring (cathodal) threshold and R-wave sensing in LBBP-ARC group indicated the critical role of ring–septum contact in ARC. Longer corrected longit-dist and shorter corrected lat-dist of lead-tip sites were positively correlated with higher success likelihood of ARC, likely due to the greater relative angle in which the lead enters the septum and consequently the longer intraseptal lead length and better ring–septum contact. CONCLUSION: This study elucidated the factors affecting the success likelihood of LBBP-ARC. These findings improve the understanding of LBBP-ARC, providing references for future research and clinical practice.