Left Bundle Branch Area Pacing Improves Left Atrial Outcomes in Pacemaker-Dependent Patients: A Prospective Cohort Study Using Speckle Tracking and Three-Dimensional Echocardiography.

Evidence that left bundle branch area pacing (LBBAP) is more effective than conventional right ventricular (RV) pacing in enhancing left atrial (LA) outcomes is lacking. The aim of this study was to investigate LA outcomes using 2-dimensional speckle tracking echocardiography (2D-STE) and real-time 3-dimensional echocardiography (RT-3DE) at 6-months of follow-up in patients that received LBBAP, RV septal pacing (RVSP), or RV apical pacing (RVAP). A total of 90 patients with normal left ventricular ejection fraction (LVEF) underwent dual-chamber pacemaker implantation for bradycardia at Beijing Anzhen Hospital between January 2021 and July 2021. Patients were divided into three groups based on the pacing site: LBBAP, RVSP, or RVAP. There were no significant differences in baseline characteristics and echocardiographic findings among patients that received LBBAP, RVSP, or RVAP. At 6-months of follow-up, left atrial volume index (LAVI), LA reservoir strain (LASr), LA contractile strain (LASct), global longitudinal strain (GLS), global circumferential strain (GCS), and synchronization parameters (Tmsv-16SD, Tmsv-12SD, Tmsv-6SD, longitudinal Tε-dif, circumferential Tε-dif) were significantly improved in patients that received LBBAP, while they had significantly worsened with RVSP and RVAP. Compared to baseline, at 6-months of follow-up, patients that received LBBAP had significantly improved LASr (28.17±10.12% vs 35.4±17.17%, P=0.024), LASct (-12.03±2.15% vs -17.53±7.37%, P=0.045), E/e' ratio(12.61±3.8 vs 10.85±3.75,P=0.014) and LVEF (65.74±7.90% vs 68.81±5.92%, P=0.023). The 6-minute walking distance significantly increased at 6-months of follow-up compared to baseline in all patients, but the increase was most prominent for LBBAP (403.00±98.46 m vs. 469.34±59.32m, P=0.015). LBBAP was associated with a lower risk of new-onset atrial fibrillation. In pacemaker-dependent patients, LBBAP achieved better LA strain, LV strain, and LV synchronization than RVSP or RVAP at 6-months of follow-up.