Evaluation of Right Heart Structure and Function in Pacemaker-dependent Patients by Two-Dimensional Speckle Tracking Echocardiography: A 1-Year Prospective Cohort Study.

Background: Left bundle branch area pacing (LBBAP) has evolved into a practical and secure pacing procedure. However, previous studies of LBBAP focused on left heart function and synchronization and lacked assessment of right heart structure and function and interventricular synchrony. The objective of this study was to examine the impacts of LBBAP, right ventricular (RV) septal pacing (RVSP), and RV apical pacing (RVAP) on right heart structure, function and interventricular synchrony.

Methods: Between January and July 2021, A total of 90 patients exhibited a normal left ventricular (LV) ejection fraction and received dual chamber pacemaker implantation for bradycardia at Beijing Anzhen Hospital. The patients were assigned to three groups based on the pacing site: LBBAP, RVSP, or RVAP. RV function was evaluated using right ventricular fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), tissue Doppler-derived tricuspid lateral annular systolic velocity (S'), right ventricular myocardial performance index (RVMPI), global longitudinal strain of the right ventricle (GLSRV), and right ventricular free wall longitudinal strain (RVFWLS). Tricuspid regurgitation (TR) was assessed using vena contracta magnitude (VCM) and the ratio of TR jet area to right atrial area (RAA). Interventricular mechanical synchrony was evaluated using interventricular mechanical delay (IVMD) and left ventricular to right ventricular time-to-peak standard deviation (LV-RV TPSD).

Results: Baseline echocardiographic parameters and characteristics were comparable among the three groups. No significant differences were observed in the LBBAP group from baseline to follow-up for QRS duration ( = 0.783), TAPSE ( = 0.122), RVFAC ( = 0.679), RVMPI ( = 0.93), GLSRV ( = 0.511), RVFWLS ( = 0.939), VCM ( = 0.467), and TR jet area/RAA ( = 0.667). In contrast, a significant decline was observed in the RVAP group (all < 0.05). RVSP resulted in a similar percentage reduction in TAPSE, GLSRV, and RVFWLS (all > 0.05). However, there were significant differences in RVFAC ( = 0.009), RVMPI ( = 0.037), TRVCM ( = 0.046), and TR jet area/RAA ( = 0.033) in the RVSP group. Moreover, compared to baseline, a 1-year follow-up showed that LBBAP significantly reduced IVMD (from 17.3 ± 26.5 ms to 8.6 ± 7.1 ms, < 0.05) and LV-RV TPSD [from 16.41 (8.81-42.5) to 12.28 (5.64-23.7), < 0.05], while RVSP and RVAP worsened IVMD and LV-RV TPSD (all < 0.05).

Conclusions: Compared with RVSP or RVAP, LBBAP can maintain RV function and improve electrical and interventricular synchrony, with limited TR deterioration after a 1-year follow-up.

Clinical Trial Registration: No. ChiCTR2100048503, https://www.chictr.org.cn/showproj.html?proj=129290.