Comparison between conduction system pacing and cardiac resynchronization therapy in right bundle branch block...

Area of Science:

• Cardiology
• Electrophysiology
• Computational Biology

Background:

• Right bundle branch block (RBBB) patients often receive cardiac resynchronization therapy (CRT) without clear evidence of benefit.
• His bundle pacing (HBP) and left bundle pacing (LBP) are emerging CRT techniques with understudied effects in RBBB.
• Understanding pacing effects on electrical synchrony in RBBB with diverse conduction issues is crucial.

Purpose of the Study:

• To compare pacing-induced electrical synchrony with conventional CRT, HBP, and LBP in RBBB patients.
• To investigate the impact of various conduction disturbances on pacing effectiveness in RBBB.
• To explore if modified LBP delivery enhances pacing response in RBBB.

Main Methods:

• Ventricular activation was simulated on 24 four-chamber heart models with His-Purkinje systems and proximal RBBB.
• Simulations included RBBB combined with left anterior/posterior fascicular blocks, and slow conduction velocity (CV) in myocardium, LV/RV His-Purkinje system, or whole His-Purkinje system.
• Electrical synchrony was quantified using the shortest interval to activate 90% of the ventricles (BIVAT-90).

Main Results:

• HBP significantly improved BIVAT-90 in RBBB alone and with LAFB, LPFB, slow myocardial CV, or slow whole His-Purkinje system CV.
• LBP was effective only when combined with anodal capture of the RV septum myocardium.
• CRT showed benefits in RBBB with slow RV His-Purkinje CV and LPFB, but both CRT and HBP were ineffective with slow LV His-Purkinje CV.

Conclusions:

• HBP is effective for RBBB patients with healthy myocardium and Purkinje systems, while CRT and LBP are less effective.
• RV septum anodal capture improves LBP response in RBBB.
• HBP is superior to CRT in most RBBB scenarios, except for those with severely slow RV His-Purkinje CV, where CRT performs better.