AimsFew data are available regarding changes in mitral regurgitation (MR) severity with guideline-directed medical therapy (GDMT) in heart failure (HF). We evaluated the evolution and impact of MR after GDMT in the BIOlogy Study to TAilored Treatment in Chronic Heart Failure (BIOSTAT-CHF).Methods and resultsA retrospective post hoc analysis was performed on HF patients from BIOSTAT-CHF with available data on MR status at baseline and at 9-month follow-up after GRMT optimization. The primary endpoint was a composite of all-cause death or HF hospitalization. Among 1022 patients with data at both time-points, 462 (45.2%) had moderate-severe MR at baseline and 360 (35.2%) had it at 9-month follow-up. Regression of moderate–severe MR from baseli...