Left bundle branch block with right axis deviation: a marker of congestive cardiomyopathy.

Three patients with primary congestive cardiomyopathy (COCM), complete left bundle branch block (LBBB) and right axis deviation in the standard leads are described. Review of 50 additional patients from the literature since 1950 indicates that the uncommon combination of LBBB and RAD is a marker of severe myocardial disease, especially COCM. The mechanism of production of this electrocardiographic pattern appears to be diffuse conduction system involvement in advanced myocardial disease.