Increasing severity of functional mitral regurgitation by left bundle branch block

A 70-year-old man with a history of hypertension and diabetes was admitted for new onset congestive heart failure. Three days later, at the time of the diagnostic echocardiography, he exhibited intermittent left bundle branch block (LBBB) and mild mitral regurgitation (MR) (panels A and B). Narrow- and LBBB-QRS complex …