Left Bundle Branch Block-associated Cardiomyopathy: A New Approach

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.