Cardiac Electrical and Mechanical Synchrony Analysis of LBBP and RVP Utilizing Tissue Doppler Imaging Technology

Right ventricular pacing (RVP) therapy is the conventional approach for atrioventricular block despite its propensity to cause electrical and mechanical dyssynchrony. This dyssynchrony increases the risk of atrial fibrillation and heart failure, eventually leading to left ventricular dysfunction. Left bundle branch pacing (LBBP) has recently emerged as a novel physiological pacing method. This study utilizes conventional ultrasound cardiography (UCG), two-dimensional speckle tracking imaging (2D-STI), and tissue Doppler imaging (TDI) to investigate the disparities in electrical and mechanical cardiac synchrony between LBBP and RVP patients.

The retrospective analysis includes data from patients who underwent LBBP (n=50) and RVP (n=50) in Zhangjiagang First People's Hospital between January 2019 and June 2020, meeting the stipulated inclusion criteria. The study compares pacing parameters, UCG metrics, cardiac electrical and mechanical synchrony, pacing success rates, and safety events both pre-operation and at 3, 6, 12, and 24 months post-operation.

Implantation success rates for both RVP and LBBP groups were 100%, with 100% and 100% pacing success rates, respectively [P = .001 RR (95% CI) : 2.5 (1.5, 3.5)]. The LBBP group exhibited significant advantages over the RVP group throughout the follow-up period. LBBP patients displayed shortened QRS duration, reduced pacing thresholds and impedance, improved sensory function, lower serum NT-proBNP levels, and an increased proportion of NYHA class I patients [P = .003 RR (95% CI) : 1.6 (1.1, 2.3)]. Furthermore, left ventricular ejection fraction increased significantly, while left ventricular diastolic and end-systolic diameters decreased in the LBBP group compared to the RVP group [P = .004 RR (95% CI) : 1.7 (1.3, 2.2)]. The LBBP group also demonstrated shorter ventricular systolic synchrony parameters, including Tls-Dif, PSD, Trs-SD, Tas-SD, Tas-post, Ts-SD, and Ts-DIf, compared to the RVP group [P = .005 RR (95% CI) : 1.5 (1.2, 2.0)]. Notably, no postoperative complications occurred in either group, such as electrode displacement, lead thrombus attachment, incision bleeding, pocket hemorrhage, or infection. However, the readmission rates for heart failure were 16% in the RVP group and 2% in the LBBP group.

LBBP achieves physiological cardiac pacing, leading to significant improvements in serum NT-proBNP levels and cardiac function and enhanced ventricular contraction synchrony. Utilizing UCG, 2D-STI, and TDI for quantitative evaluation of cardiac electrical and mechanical synchrony proves to be a valuable clinical approach.