Quantitative distance and electrocardiographic parameters for lead-implanted site selection to enhance the success likelihood of left bundle branch pacing

Background: Left bundle branch pacing (LBBP) is a novel near-physiological pacing method that still lacks quantitative criteria to guide the selection of lead-implanted sites to enhance the success likelihood of lead deployments. This study aimed to quantitatively analyze the relationships of LBBP success likelihood to the distribution of lead-implanted sites and the lead-localization-pacing electrocardiographic (ECG) features.

Methods: All the lead-implanted sites in patients with finally successful LBBP were enrolled for analysis, including successful and failed sites. A novel coordinate system was invented to describe the sites' distribution as longitudinal distance (longit-dist) and lateral distance (lat-dist). Corrected distance parameters were generated to eliminate the cardiac dimension variations. The lead-localization-pacing ECG parameters were also collected, such as paced QRS duration (locat-QRSd), left ventricular activation time (locat-LVAT), LVAT/QRSd ratio (locat-LVAT/QRSd), and QRS directions.

Results: A total of 94 patients with 105 successful sites and 93 failed sites were enrolled. Longit-dist and corrected longit-dist of successful sites were significantly longer, while locat-QRSd and locat-LVAT were shorter and locat-LVAT/QRSd was lower than failed sites. There was a positive dose-response relationship between LBBP success likelihood and corrected longit-dist with a cut-off of 26.95 mm, whereas there were negative dose-response relationships of LBBP success likelihood to locat-QRSd, locat-LVAT, and locat-LVAT/QRSd with the cut-offs of 142 ms, 92 ms, and 64.7%, respectively. Downward QRS direction in II/III ECG leads was also associated with successful LBBP.

Conclusion: Longit-dist, locat-QRSd, locat-LVAT, and locat-LVAT/QRSd were quantitative parameters to guide the selection of lead-implanted sites during LBBP implantation. Quantitative distance and electrocardiographic parameters for lead-implanted site selection to enhance the success likelihood of left bundle branch pacing. LBBP, left bundle branch pacing; Longit-dist, longitudinal distance; CL-apex-dist, distance from contraction line to apex; LBBB, left bundle branch block; IVCD, intraventricular conduction delay; Locat-QRSd, lead-localization-pacing QRS duration; Locat-LVAT, lead-localization-pacing left ventricular activation time; Locat-LVAT/QRSd, lead-localization-pacing LVAT/QRSd ratio.