Left Bundle Branch Area Pacing Preserves Mechanical Strain and Synchrony Compared to Right Ventricular Apical Pacing in an Acute Paired Preclinical Model

BackgroundLeft bundle branch area (LBBA) pacing is emerging as a promising alternative to conventional right ventricular (RV) pacing, particularly in its ability to maintain physiological ventricular activation and enhance cardiac function. However, the effect of LBBA pacing on changes to left ventricular (LV) function in paired experiments on healthy hearts, particularly in relation to myocardial strain and time to peak systolic strain difference (TPSD), which are critical indicators of LV dysfunction, remains inadequately understood. ObjectiveTo investigate how the LV myocardial strain and TPSD change in a comparative study of LBBA pacing versus conventional RV apex pacing in the same hearts under normal physiological conditions. MethodsPre-clinical canine models (n=7) were implanted with pacing leads in the LBBA and RV apex. Functional parameters were assessed under acute pacing conditions and during sinus rhythm (SR) with echocardiographic assessment. ResultsResults demonstrated that LBBA pacing significantly improved global longitudinal strain (GLS: -13{+/-}2% vs. -9{+/-}2%, p = 0.0003) and global circumferential strain (GCS: -16{+/-}3% vs. -10{+/-}4%, p = 0.0119) compared to RV apical pacing. TPSD was significantly greater with RV pacing (65{+/-}10 ms vs. 24{+/-}7 ms, p = 0.0024). Compared with SR data, LBBA pacing showed no significant changes in GLS, GCS, or TPSD. ConclusionThese findings suggest that LBBA pacing effectively preserves global myocardial strain and TPSD close to their values in SR, thereby contributing to enhanced overall LV function, as evidenced by improvements in ejection fraction, end-systolic volume, and end-diastolic volume.