Efficacy of His Bundle Pacing on LV Relaxation and Clinical Improvement in HF and LBBB

Objectives: This study aimed to compare acute hemodynamic improvements and responses to His bundle pacing (HBP) and conventional biventricular pacing (BVP).

Background: HBP can correct left bundle branch block (LBBB) and may be an alternative cardiac resynchronization therapy (CRT) to BVP.

Methods: Fourteen consecutive patients with heart failure (HF) and typical LBBB who required CRT were enrolled. The acute hemodynamic responses during HBP and BVP were compared using a micromanometer-tipped catheter inserted into the left ventricle (LV) before CRT. Each configuration was compared with AAI mode. A permanent HBP device was implanted when LBBB correction threshold was ≤1.5 V at 1.0 ms, and remaining patients were treated with BVP. Clinical and echocardiographic improvements were assessed during a 12-month follow-up period.

Results: The LV contractile index (positive maximal rate of LV pressure rise [dP/dt_max]) increased similarly during HBP and BVP (18.8% ± 6.4% vs 18.0% ± 10.2%; P = 0.810). LV relaxation indices (negative dP/dt_max and tau) were significantly improved during HBP compared with BVP (negative dP/dt_max: 14.3% ± 5.5% vs 3.1% ± 8.1%; P < 0.001; tau: 7.2% ± 4.3% vs -0.8% ± 8.1%; P = 0.001). Nine (64%) patients received permanent HBP devices, while 5 patients were treated with BVP. The New York Heart Association functional class, LV ejection fraction, LV end-systolic volume, and B-type natriuretic peptide level improved in patients treated with HBP and BVP (all P < 0.05 vs baseline). Patients treated with HBP exhibited earlier and greater improvements of the LV ejection fraction and LV end-systolic volume than did those with BVP.

Conclusions: HBP improves systolic function and LV relaxation in patients with HF and LBBB. CRT via HBP produced earlier and greater clinical responses than BVP.