Percutaneous balloon mitral valvotomy with the Inoue single-balloon catheter: commissural morphology as a determinant of outcome.

OBJECTIVES: The aim of this study was to determine the importance to outcome and the predictability of commissural splitting in patients undergoing percutaneous mitral valvotomy with the Inoue single-balloon catheter. BACKGROUND: Echocardiographic scoring systems devised to predict mitral valvotomy outcome are based on assessment of leaflet and subvalvular morphology, but the specific importance of commissural morphology has not been examined. METHODS: In 30 consecutive patients, commissural splitting was predicted on the basis of the two-dimensional echocardiographic commissural morphology: the extent of fusion, fibrosis or calcification of each commissure. Valve morphology also was evaluated according to a previously described echocardiographic scoring system. RESULTS: Splitting of one or both commissures occurred in 24 patients (80%) and was associated with a significantly greater mean increase in valve area (85%) than if neither commissure was split (13%). A good outcome from valvotomy (defined as valve area > 1.5 cm2 and increase in valve area > 25%) was achieved in 96% of those in whom one or both commissures split, but in none of the patients in whom neither commissure split. Whether or not splitting of at least one commissure would occur was predicted accurately in 28 (93%) of the 30 patients. Consequently, the prediction that one or both commissures would split was associated with a good outcome in 23 (89%) of 26 patients, whereas the prediction that neither commissure would split was not associated with a good outcome in any patient. There was no significant difference in the increase in mitral valve area between those with a mitral echocardiographic score < 8 and those with a score > or = 8. New or worsening mitral regurgitation occurred in nine patients, most commonly as a jet directed through a split commissure. CONCLUSIONS: Commissural splitting is the dominant mechanism by which mitral valve area is increased with the Inoue balloon technique, and it can be predicted by echocardiographic assessment of commissural morphology. Commissural morphology is a better predictor of outcome than is the mitral echocardiographic score.