What is the clinical evidence from this study?

Study design: Review. Population: Left bundle branch block-associated cardiomyopathy. Intervention: Conduction system pacing (Left bundle branch pacing) vs. Biventricular pacing.

September 25, 2024Open Access

Left Bundle Branch Block-associated Cardiomyopathy: A New Approach

Key Result

Left bundle branch block-associated cardiomyopathy represents a potentially reversible condition where conduction system pacing offers superior electromechanical resynchronization compared to biventricular pacing.

Structured PICO

Does cardiac resynchronisation therapy by left bundle branch pacing improve reverse remodelling in patients with LBBB-associated cardiomyopathy?

Population

Patients with cardiomyopathy (ejection fraction <35%) and left bundle branch block (LBBB)

Intervention

Cardiac resynchronisation therapy (CRT) by left bundle branch pacing / conduction system pacing

Comparator

Medical therapy alone

Outcome

Reverse remodelling and clinical outcomes

LBBB-associated cardiomyopathy is a potentially reversible condition where conduction system pacing (left bundle branch pacing) can lead to significant reverse remodeling, potentially challenging the guideline recommendation to wait 3 months on medical therapy before CRT.

Limitations

Lack of large randomized head-to-head comparisons between biventricular pacing and left bundle branch pacing
Strict criteria for diagnosing LBBB-induced cardiomyopathy may miss patients who could benefit from early resynchronization therapy
The exact mechanisms causing left ventricular dysfunction in only a subset of LBBB patients remain largely unknown

Abstract

Left bundle branch block (LBBB) is frequently associated with structural heart disease, and predicts higher rates of morbidity and mortality. In patients with cardiomyopathy (ejection fraction <35%) and LBBB, current guidelines recommend cardiac resynchronisation therapy (CRT) after 3 months of medical therapy. However, studies have suggested that medical therapy alone would be less effective, and the majority of patients would still need CRT at the end of 3 months. Conversely, CRT trials have shown better results and favourable clinical outcomes in patients with LBBB. In the absence of any other known aetiology, LBBB-associated cardiomyopathy represents a potentially reversible form of cardiomyopathy, with the majority of the patients having reverse remodelling after CRT by left bundle branch pacing. This review provides the mechanism, published evidence and role of conduction system pacing for patients with LBBB-associated cardiomyopathy.

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