Evaluation of the shortening of the stimulus-to-peak left ventricular activation time at continuous low output to confirm left bundle branch capture

BACKGROUND: Left bundle branch area pacing (LBBAP) is a physiological pacing method for treatment of atrioventricular block. However, there is a need for a new convenient and safe method for performing left bundle branch pacing (LBBP) and to confirm left conduction system capture. OBJECTIVE: This study aimed to explore a new convenient and safe method for performing selective LBBP. METHODS: A total of 28 patients who had indications for pacing therapy and received LBBAP were recruited retrospectively. Demographic and baseline patient characteristics, electrocardiograms, pacing parameters, and intracardiac electrogram pattern were evaluated. Continuous unipolar pacing at low output (2 V / 0.5 ms) was performed during the whole period of LBBP lead implantation. Successful left bundle branch (LBB) capture was defined as the abrupt change of the pacing stimulus to the peak of R wave in lead V(5) during continuous pacing at low output (2 V / 0.5 ms). RESULTS: The parameters of the 2 shortenings (stimulus-to-peak left ventricular activation time [S-peak LVAT] before shortening, S-peak LVAT after shortening, and the duration of shortening) all showed a significant positive correlation (Pearson product-moment correlation coefficient [PCC] = 0.915, P < .001; PCC = 0.897, P < 0.001; PCCs = 0.765, P < 0.001). Shortening of the S-peak LVAT with continuous low output had a 100% sensitivity and 33.3% specificity for predicting stimulus-ventricular potential interval (S-V interval). CONCLUSION: Abrupt shortening of the S-peak LVAT at continuous low output was associated with abrupt shortening of the S-peak LVAT at low and high output. High rate of selective LBB capture can be achieved with the method of continuous low output, shortening the S-peak LVAT.