LVSP and LBBP Result in Similar or Improved LV Synchrony and Hemodynamics Compared to BVP

The effect of left ventricular myocardial septal (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and LV hemodynamics is poorly understood. To investigate the impact of LVSP and LBBP versus biventricular pacing (BVP) on ventricular electrical synchrony and hemodynamics in CRT patients. In CRT candidates with LV conduction disease, ventricular synchrony was assessed by measuring QRSd and using ultra-high-frequency ECG (UHF-ECG). LV electrical synchrony (lv-DYS) was assessed as a difference between the first activation in V1-V8 to the last from V4-V8. LV hemodynamics was estimated using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and BVP. Thirty-five patients with LVEF of 29% and QRSd 16824 ms were included. Thirteen had ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter lv-DYS than BVP (-10 ms (95% CI: -16; -4), p = 0.001); the difference between LVSP and BVP was not significant (-5 ms (95% CI: -12; 1), p = 0.1). LBBP was associated with higher systolic blood pressure than BVP (4% (95% CI: 2; 5) p < 0.001), while LVSP was not (95% CI: 1% (0; 2), p = 0.1. Hemodynamic differences during LBBP and LVSP vs. BVP were more pronounced in non-ischemic than ischemic patients. UHF-ECG allowed the documentation of differences in LV synchrony between LBBP, LVSP, and BVP, which were not observed by measuring QRSd. LVSP provided the same LV synchrony and hemodynamics as BVP, while LBBP was better than BVP in both.