His or para-His pacing preserves left ventricular function in atrioventricular block: a double-blind, randomized,...

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Pacing

Background:

• Atrioventricular block (AVB) often necessitates pacemaker implantation.
• Traditional right ventricular pacing can lead to dyssynchrony and impaired left ventricular function.
• His or para-His pacing (HP) offers a more physiological alternative, potentially preserving cardiac function.

Purpose of the Study:

• To compare left ventricular function and mechanical synchrony between long-term His or para-His pacing (HP) and right ventricular septal pacing (RVSP).
• To evaluate the impact of pacing strategy on left ventricular ejection fraction (LVEF) and regional myocardial function in patients with AVB.

Main Methods:

• Prospective, randomized, double-blinded, crossover study involving 38 patients with AVB, narrow QRS, and preserved LVEF.
• Patients underwent 12 months of HP followed by 12 months of RVSP, or vice versa.
• Left ventricular ejection fraction (LVEF) and mechanical synchrony (assessed by tissue Doppler imaging) were primary endpoints.

Main Results:

• LVEF was significantly higher after 12 months of HP (0.55 ± 0.10) compared to RVSP (0.50 ± 0.11) (P = 0.005).
• Mechanical synchrony, measured by time-to-peak systolic velocity differences, showed significant improvements with HP in multiple views (P = 0.02-0.03).
• No significant differences were observed in functional class, exercise capacity, quality of life, or device complications.

Conclusions:

• His or para-His pacing effectively preserves LVEF and mechanical synchrony over RVSP in patients with AVB.
• HP represents a superior pacing strategy for maintaining left ventricular function and synchrony in this patient population.