Mitral Regurgitation (Mitral Insufficiency) By Guy P Armstrong, MD, Waitemata District Health Board and Waitemata Cardiology, Auckland Reviewed / Revised Jul 2022 | Modified Sep 2022 View Patient Education Etiology Pathophysiology Symptoms and Signs Diagnosis Prognosis Treatment Key Points Topic Resources Mitral Regurgitation Murmur... Mitral Regurgitation Murmur Grading of Mitral Regurgitation Mitral Regurgitation Mitral regurgitation (MR) is incompetency of the mitral valve causing flow from the left ventricle (LV) into the left atrium during ventricular systole.