Mitral Regurgitation After Percutaneous Mitral Valvotomy

Mitral regurgitation (MR) after percutaneous mitral balloon valvotomy (PMV) is commonly an end point and may be a significant complication. Some increase in MR occurs in more than half of patients undergoing PMV. An increase > 2 grades occurs in 3%–1.5% of patients, and < 5% have severe MR as a complication. MR is a significant predictor for late cardiac events and preexisting MR before PMV is also associated with poor late outcome. Mild increases in MR are due to stretching of the annulus, excess commissural tearing, or papillary muscle trauma. Mild MR frequently disappears at follow‐up and rarely increases. Risk factors for development of MR have varied among multiple studies. Balloon oversizing and entrapment/tearing of chordae by the balloon(s) are mechanical factors. Most predictors are related to the pathologic anatomy of the mitral valve. Older age, a larger end‐systolic volume index, and lower ejection fraction may be independent predictors of progression of MR. Subvalvular disease and valve thickening have also been identified as predictors. A recently described “scoring” system for predicting MR considers the distribution of anterior and posterior leaflet thickening, extent of commissural calcification/fibrosis, and degree of subvalvular disease. “Even” calcification/thickening produces a “lower” or “better” score than “uneven” distribution. Bicommissural calcification and thickening and shortening of chordae all predict bad outcome. Thus careful echocardio‐graphic evaluation of mitral valve pathoanatomy pre‐PMV can identify most predictors of the development of MR.