RESUMEN
BACKGROUND: Commissural morphology is an important predictor of outcome following balloon mitral valvotomy. The aim of this prospective study was to assess if the site of commissural splitting could be reliably predicted by echocardiography and whether the extent of commissural split affected the result of balloon mitral valvotomy. METHODS AND RESULTS: A total of 140 patients (mean age 29.1+/-8.6 years) were studied. Prediction of splitting was done based on the presence of echolucent dark zones as seen in the parasternal short-axis view on echocardiography. Of 102 patients in whom a split of both commissures was predicted, the prediction was accurate in 86% (88/102). Of 33 patients with a predicted unilateral split, the accuracy of prediction was 82% (27/33). In the 5 patients with bilateral commissural fibrosis (in whom none of the commissures were predicted to split), all had a unilateral split. Overall, 93 patients (66%) had a bilateral commissural split, 43 (31%) had a unilateral split, and 4 had no commissural split. All the latter 4 developed moderate-to-severe mitral regurgitation. Those with bilateral commissural split following balloon mitral valvotomy had lower transmitral gradients (5.53+/-1.46 v 7.4+/-1.2 3 mmHg, p = 0.03) and greater mitral valve area (1.83+/-0.15 v. 1.64+/-0.15 cm2, p<0.02), as compared to those with unicommissural split. The incidence of an increase in mitral regurgitation by > or = grade 1 was also lower in the former group (7.5% v. 28%). An optimal result with the first dilatation (using a balloon size <2 mm of the predicted size) was achieved more frequently in those with a bilateral split (18% vs 8%). Oversizing of the balloon by 2 mm (of the predicted size) was done more frequently (19% v. 7%) in those with unicommissural split. CONCLUSIONS: We conclude that the assessment of commissural morphology is possible with excellent predictive accuracy. In this study, those with bilateral commissural split had more favorable hemodynamic results with lower transmitral gradients. greater mitral valve area and lesser frequency of mitral regurgitation in contrast to those with unicommissural split.