Influence of mitral valve morphology on mitral balloon commissurotomy: Immediate and six-month results from the NHLBI Balloon Valvuloplasty Registry

Abstract

Echocardiographic data were analyzed in 555 patients undergoing mitral balloon commissurotomy (MBC). Patients were enrolled in the National Heart, Lung, and Blood Institute Balloon Valvuloplasty Registry from 24 centers. There were 456 women and 99 men with a mean age of 54 years. Before MBC the two-dimensional echocardiographic variables of mitral valve thickness, mobility, calcification, and subvalvular disease were evaluated and assigned scores of 1 to 4. The mitral valve morphology score was related to mitral valve area (MVA) measured after MBC by cardiac catheterization. The leaflet mobility score was related to the immediate post-MBC MVA: 2.2 ± 0.8 cm 2 for grade 1, 1.9 ± 0.7 cm 2 for grade 2, 1.7 ± 0.7 cm 2 for grade 3, and 1.9 ± 0.9 cm 2 for grade 4 ( p < 0.001). Results of the MVA after MBC showed a similiar relationship for each echocardiographic variable. The total morphology score (sum of the four variables) showed a weak relationship to MVA immediately after MBC ( r = −0.24), which was persistent at 6 months after MBC ( r = −0.25). Multiple regression analysis showed that the MVA after MBC is predicted by pre-MBC MVA ( p < 0.001), left atrial size ( p = 0.01), balloon diameter ( p = 0.02), cardiac output ( p = 0.004), and leaflet mobility ( p = 0.01). The R 2 of the model was 0.31 ( p < 0.001). Total morphology score, leaflet thickness, calcification, and subvalvular disease were not important univariate or multivariate predictors of the results of MBC. These data suggest that although mitral valve morphology, particularly leaflet mobility, relates to MVA after MBC, other variables such as the severity and duration of disease are also important and are influenced by the larger balloon sizes used in the procedure. Mitral valve morphology should not be used alone in the selection of patients for MBC.