Left ventricular subendocardial pacing provides the same left ventricular synchrony and work efficiency as direct...

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Left septal myocardial pacing (LVSP) encompasses pacing in areas of difficult left bundle branch (LBB) capture or LV subendocardial locations.
• LV subendocardial pacing (LVSeP) occurs during decremental output pacing when transition from LBB pacing (LBBP) is observed.

Purpose of the Study:

• To compare electrical ventricular synchrony and acute hemodynamic response between LBBP and LVSeP.
• To evaluate the efficacy of LVSeP as an alternative pacing strategy in cardiac resynchronization therapy (CRT).

Main Methods:

• Enrolled consecutive CRT patients who transitioned from non-selective LBBP (nsLBBP) to LVSeP during decremental output pacing.
• Assessed ventricular dyssynchrony using high-frequency electrocardiography (UHF-ECG) and acute hemodynamic response via invasive systolic blood pressure measurements.
• Performed invasive intracardiac mapping of the left ventricular septum during both pacing modes.

Main Results:

• No significant difference in QRS duration (QRSd) between LVSeP and LBBP (159 ± 18 ms vs. 151 ± 15 ms).
• LVSeP showed longer V6RWPT and post-pacing isoelectric interval, but similar LV synchrony (14 ± 5 ms vs. 16 ± 6 ms) and systolic blood pressure (121 ± 18 mmHg vs. 122 ± 17 mmHg) compared to LBBP.
• Intracardiac mapping indicated both LVSeP and LBBP activated the LV septum via the His-Purkinje system.

Conclusions:

• LVSeP preserves left ventricular synchrony and acute hemodynamic response similarly to direct LBBP in CRT candidates.
• LVSeP represents a potentially effective alternative pacing strategy when direct LBBP is not feasible.
• Further research is needed to elucidate differences among various left septal pacing techniques.