Two physiologic types of mitral regurgitation (MR) are generally recognized: primary (organic) and secondary (functional). Although both types share the common thread of an incompetent mitral valve, their causative mechanisms, therapies, and outcomes are strikingly different from one another.
In primary MR, an anatomic abnormality in the structure of the valve causes it to leak. Causative mechanisms include fibroelastic deficiency disease, Barlow disease, rheumatic disease, and infective endocarditis. Primary MR is the disease wherein the valve abnormalities cause left ventricular (LV) volume overload, neurohormonal activation, LV damage, and eventual death. Fortunately, timely valve repair can be curative, allowing for restoration of mitral competence, LV function, and longevity.1