Comparison of electrophysiological left bundle branch pacing characteristics in different bilateral electrode pacing vector configurations

Background Left bundle branch pacing (LBBP) in bipolar pacing produces a more balanced ventricular activation than conventional unipolar pacing but need high pacing output. The present study aimed to compare the electrophysiological characteristics of LBBP in different bilateral electrode pacing vector configurations. Methods A total of 57 patients who met the criteria for left bundle branch (LBB) capture and underwent three bilateral electrode pacing vector configuration test were enrolled. The electrocardiogram (ECG) and electrogram (EGM) parameters were evaluated and other electrophysiological characteristics were analyzed using a three-electrode configuration test. Results Seven capture modes (right ventricular septal (RVS) + left ventricular septal (LVS) + LBB, RVS + LBB, LVS + LBB, RVS + LVS, RVS, LVS, and LBB) were utilized in the study. The thresholds of full fusion mode (RVS+LVS+LB) in Bilateral Cathodes and Ring Bipolar were all lower than that in Tip Bipolar (1.2 ± 0.5 V vs. 2.7 ± 1.0 V, P < 0.001; 1.6 ± 0.6 V vs. 2.7 ± 1.0 V, P < 0.001). Full fusion mode had the shortest P-QRS (116.9 ± 12.8 ms), V6 RWPT (64.9 ± 9.7 ms), and V1 RWPT (94.5 ± 12.3 ms). Conclusion Changing the bilateral electrode pacing vector configuration to Bilateral Cathodes and Ring Bipolar can reduce the full fusion mode capture threshold compared to conventional bipolar pacing. What is Known? Left bundle branch pacing in bipolar pacing can capture left bundle branch, left ventricular septal myocardial, and right ventricular septal myocardial at a higher pacing output, which was termed full fusion mode. What the Study Adds? This study indicates that the full fusion mode threshold can be reduced by changing the pacing vector configuration. Seven capture modes were observed in Ring Bipolar and Bilateral Cathodes during threshold testing. GRAPHICAL ABSTRACT The characteristics of ECG and EGM of different types of capture in three bilateral electrode pacing vector configurations and the schematic representation.