Relationship Between Electrical Parameters and Cardiac Synchrony in Patients Underwent Left Bundle Branch Area Pacing

PURPOSE: The study aims to assess cardiac synchrony under different left bundle branch area pacing (LBBAP) and evaluate the relationship between different surface or intracardiac electrical parameters and mechanical synchrony. METHODS: Eighty-two patients with successful LBBAP were recruited. The electrical synchrony, evaluated by paced QRS duration (pQRSD) and Stim-LVAT (stimulus to left ventricular activation time), and mechanical synchrony, evaluated by the standard deviation of the time-to-peak contraction velocity in 12 left ventricular segments (Tsd-12-LV), were compared between groups in patients underwent LBBAP. To investigate the relationship between different electrical parameters with mechanical synchrony under LBBAP, patients were divided into subgroups according to left ventricular activation time (LVAT, < 60, 60-70, and > 70 ms), presence of left bundle branch (LBB) potential (positive, negative), QRS axis (normal, left axis deviation [LAD]), and potential to ventricular interval (PVI, < 20 and > 20 ms). Mechanical synchrony was compared among the subgroups respectively 3 days post LBBAP procedure. RESULTS: No statistically significant differences were documented in electrical synchrony, evaluated by pQRSD, and mechanical synchrony, evaluated by Tsd-12-LV among the subgroups divided by the stim-LVAT, LBB potential, PVI duration, or paced QRS axis in the LBBAP group. CONCLUSIONS: LBB potential, PVI, or normal paced QRS axis is not the prerequisite for successful LBBAP and optimal cardiac synchrony. Adopting a Stim-LVAT value of less than 75 ms to attain ideal electrical and mechanical synchrony during the LBBAP procedure may be applicable. TRIAL REGISTRATION: http://www.chictr.org.cn/index.aspx. CLINICALTRIALS: gov identifier: ChiCTR1800021104.