Can the long-term outcomes of percutaneous balloon mitral valvotomy and surgical commissurotomy be expected to be similar?

Abstract

The ultimate role of percutaneous balloon mitral valvotomy will depend on its potential for sustained improvement. Long-term outcome data including survival, reoperation and thromboembolism are available for surgical commissurotomy. However, length of follow up for percutaneous balloon mitral valvotomy is inadequate to acquire similar end-point data. We therefore hypothesized that comparison of changes in mitral valve area following balloon or surgical commissurotomy would serve as a useful surrogate end-point by which the long-term benefit of percutaneous balloon mitral valvotomy could be determined. Mitral valve area was determined by Doppler echocardiography following percutaneous balloon mitral valvotomy (N = 230) and surgical commissurotomy (N = 241, 130 closed and 111 open mitral commissurotomy). Regression lines of mitral valve area versus interval from intervention were constructed for each of the two groups. Nine clinical and echocardiographic variables were also analyzed to determine their predictive value for low mitral valve areas. Both groups showed similar and significant negative correlations for mitral valve area versus time (r = -0.48, r = -0.6, balloon vs. surgical commissurotomy respectively, p = 0.001 for both groups). The slopes of the regression lines for both groups were also similar (y = -0.007 x +1.9, y = -0.005 x +1.8, y = -0.006 x +1.8, p = NS). There were no differences in the prevalence of mitral regurgitation. Independent predictors of mitral restenosis according to multivariate analysis were time interval from surgery (p < 0.03), composite mitral valve morphology score (p < 0.04) and subvalvular disease (p < 0.04). Thus, there is a progressive decrease in mitral valve area following percutaneous mitral balloon valvotomy that, at least for the available duration of follow up, appears to parallel changes in valve area following closed or open mitral commissurotomy. A less pliable valve and more subvalvular disease are independent predictors of smaller valve areas. These data suggest that the long term clinical outcome following percutaneous balloon mitral valvotomy may be expected to be similar to the available data for surgical commissurotomy.