Left bundle branch block-induced dilated cardiomyopathy: Definitions, pathophysiology, and therapy.

Left bundle branch block (LBBB) is a frequent finding in patients with heart failure (HF), particularly in those with dilated cardiomyopathy (DCM). LBBB has been commonly described as a consequence of DCM development. However, a total recovery of left ventricular (LV) function after cardiac resynchronization therapy (CRT), observed in patients with LBBB and DCM, has led to increasing acknowledgement of LBBB-induced dilated cardiomyopathy (LBBB-iDCM) as a specific pathological entity. Its recognition has important clinical implications, as LBBB-iDCM patients may benefit from an early CRT strategy rather than medical HF therapy only. At present, there are no definitive diagnostic criteria enabling the universal identification of LBBB-iDCM, and no defined therapeutic approach in this subgroup of patients. This review compiles the main findings about LBBB-iDCM pathophysiology and the current proposed diagnostic criteria and therapeutic approach.