Focal Replacement and Diffuse Fibrosis in Primary Mitral Regurgitation A New Piece to the Puzzle

most frequent valvular heart diseases. The most common etiology of primary MR is the myxomatous degeneration of the mitral valve, encompassing fibroelastic deficiency and Barlow's disease. In severe chronic primary MR, the presence of symptoms, reduced left ventricular ejection fraction (LVEF) #60%, and increased left ventricular (LV) end-systolic diameter are indications for mitral valve repair (1,2). In asymptomatic patients, surgery should be considered if there is a high likelihood of durable mitral valve repair; low operative risk; and atrial fibrillation, pulmonary hypertension, flail leaflet, or dilated left atrium at sinus rhythm (1,2). The evidence showing the benefits of early surgery is accumulating. Data from a large cohort of 1,512 patients undergoing mitral valve surgery for isolated primary MR revealed that patients who were operated based only on high likelihood of successful mitral valve repair had the best outcome (3). The rationale for an early intervention is that the longstanding volume overload caused by severe MR may lead to irreversible LV dysfunction. LVEF is considered the parameter of reference to define LV function and toCardiolog