His bundle pacing to avoid electrical dyssynchrony with traditional right ventricular pacing: Importance of heart...

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Pacing

Background:

• Right ventricular pacing (RVP) can induce electrical dyssynchrony.
• His bundle pacing (HBP) is an emerging alternative to RVP, aiming to preserve native electrical conduction.
• Understanding factors influencing HBP's benefit is crucial for optimizing pacing strategies.

Purpose of the Study:

• To evaluate the impact of heart size, specifically left ventricular end-diastolic volume (LVEDV), on the electrical benefits of HBP compared to RVP.
• To determine if LVEDV influences the degree of electrical synchrony achieved with HBP versus RVP.

Main Methods:

• Fifty-nine patients receiving HBP with RVP backup had pre-implantation echocardiography to measure LVEDV.
• Electrical benefit was quantified by the difference in QRS duration (QRSd) between RVP and HBP.

Main Results:

• Left ventricular end-diastolic volume (LVEDV) strongly correlated with RVP QRSd (R=0.53, p<0.001) but not with HBP QRSd (R=0.16, p=0.24).
• The electrical benefit of HBP over RVP was directly related to LVEDV (R=0.43, p=0.001).
• Patients with LVEDV above the median (99 mL) showed significantly greater electrical benefit from HBP (49 ± 27 ms) compared to those below the median (34 ± 19 ms, p=0.014).

Conclusions:

• This study is the first to show that larger left ventricular (LV) size predicts greater electrical benefit from His bundle pacing (HBP) over traditional right ventricular pacing (RVP).
• LV size influences QRS duration during RVP due to slower conduction, whereas HBP, utilizing faster His-Purkinje system conduction, is less affected by LV size.
• These findings suggest HBP may be a more effective strategy for achieving electrical synchrony in patients with larger hearts.