Effect of Cardiac Resynchronisation Therapy on Electrical Remodelling

Area of Science:

• Cardiology
• Electrophysiology

Background:

• Cardiac resynchronisation therapy (CRT) improves heart function in patients with low ejection fraction.
• CRT's beneficial effects are linked to mechanical remodelling.
• The impact of CRT on electrical remodelling, specifically QRS duration, remains debated.

Purpose of the Study:

• To evaluate the effects of CRT on intrinsic QRS duration.
• To investigate if CRT induces electrical remodelling by measuring QRS duration using signal-averaged electrocardiogram (SAECG).

Main Methods:

• 48 patients with systolic dysfunction and left bundle branch block (LBBB) underwent CRT-D implantation.
• Intrinsic QRS duration was measured using SAECG before and at least 14 months after CRT implantation.
• Patients were categorized as CRT responders or non-responders.

Main Results:

• Mean intrinsic QRS duration showed no significant change post-CRT (149.9±13.8ms vs. 149.6±18.4ms; P=0.3).
• Intrinsic QRS duration remained unchanged in both CRT responders and non-responders.
• No significant difference in QRS duration was observed during follow-up.

Conclusions:

• CRT-induced structural remodelling does not necessarily decrease intrinsic ventricular activation.
• Electrical characteristics of the left ventricular conduction system may not improve after CRT.
• CRT's effect on electrical remodelling is minimal, despite positive effects on mechanical function.