Ventricular repolarization is improved by His resynchronization therapy but not biventricular pacing

Area of Science:

• Electrophysiology
• Cardiology
• Medical Devices

Background:

• Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP-CRT) offers modest benefits for heart failure patients with left bundle branch block (LBBB) but can induce ventricular arrhythmias.
• His bundle pacing (HBP) presents an alternative CRT strategy that corrects LBBB, leading to superior ventricular activation synchrony and hemodynamics compared to BVP-CRT.

Purpose of the Study:

• To compare the effects of His bundle pacing cardiac resynchronization therapy (HBP-CRT) versus biventricular pacing cardiac resynchronization therapy (BVP-CRT) on ventricular repolarization.
• To investigate the impact of HBP-CRT and BVP-CRT on repolarization dispersion, gradient, and activation-recovery interval (ARI) in LBBB patients.

Main Methods:

• Intra-procedural non-invasive epicardial mapping was performed on LBBB patients undergoing BVP-CRT.
• Measurements included global and left ventricular (LV) repolarization dispersion (ΔVRT, ΔLVRT), gradient (ΔVRG, ΔLVRG), and ARI dispersion (ΔVARI, ΔLVARI) during intrinsic LBBB, BVP-CRT, and HBP.

Main Results:

• BVP-CRT showed no significant effect on global repolarization parameters and worsened LV repolarization (ΔLVRT P=.049, ΔLVARI P=.02).
• HBP-CRT significantly improved global repolarization dispersion, gradient, and ARI (ΔVARI P<.0001).
• HBP-CRT also significantly improved LV repolarization parameters (ΔLVRT P<.001, ΔLVRG P=.0003, ΔLVARI P=.003).

Conclusions:

• HBP-CRT effectively addresses LBBB-induced repolarization abnormalities by enhancing activation synchrony and modulating ARI.
• In contrast, BVP-CRT offers no improvement and may adversely affect LV repolarization parameters in LBBB patients.