Etiology of Mitral Regurgitation Mitral regurgitation may be Acute or chronic Primary or secondary Causes of acute mitral regurgitation include Ischemic papillary muscle dysfunction or rupture Infective endocarditis with rupture of the chordae tendineae Acute rheumatic fever Myxomatous rupture of the chordae tendineae Acute dilation of the left ventricle due to myocarditis or myocardial ischemia Mechanical failure of a prosthetic mitral valve Common causes of chronic mitral regurgitation are intrinsic valve pathology (primary MR) or distortion of a normal valve by dilatation and impairment of the left ventricle and / or the mitral annulus (secondary MR).