Percutaneous balloon versus surgical closed commissurotomy for mitral stenosis. A prospective, randomized trial BACKGROUND. We performed a prospective, randomized trial comparing percutaneous balloon commissurotomy with surgical closed commissurotomy in 40 patients with severe rheumatic mitral stenosis. METHODS AND RESULTS. Data were analyzed by investigators who were masked to treatment assignment or phase of study. Patients randomized to balloon (n = 20) or surgical (n = 20) commissurotomy had severe mitral stenosis without significant baseline differences (left atrial pressure, 26.1 +/- 4.2 versus 27.6 +/- 6.2 mm Hg; mitral valve gradient, 18.0 +/- 4.2 versus 19.7 +/- 6.3 mm Hg; mitral valve area, 1.0 +/- 0.2 versus 1.0 +/- 0.4 cm2, respectively). At 1-week follow-up after balloon commissurotomy, pulmonary wedge pressure was 14.3 +/- 7.2 mm Hg; mitral valve gradient was 9.6 +/- 5.1 mm Hg; and mitral valve area was 1.6 +/- 0.6 cm2 (all p less than 0.0001). At 1-week follow-up after surgical closed commissurotomy, wedge pressure was 13.7 +/- 5.4 mm Hg; mitral valve gradient was 9.4 +/- 4.2 mm Hg (both p less than 0.0001); and mitral valve area was 1.6 +/- 0.7 cm2 (p less than 0.003). At 8-month follow-up, improvement occurred in both groups: Mitral valve area was 1.6 +/- 0.6 cm2 in the balloon commissurotomy group (p less than 0.002) and was 1.8 +/- 0.6 cm2 in the surgical closed commissurotomy group (p less than 0.0001). There was no difference between the groups at 1-week or 8-month follow-up (all p greater than 0.4). One case of severe mitral regurgitation occurred in each group; complications were otherwise related to transseptal catheterization. There was no death, stroke, or myocardial infarction. Cost analysis revealed that balloon commissurotomy may substantially exceed the cost of surgical commissurotomy in developing countries, whereas it may represent a significant savings in industrialized nations. CONCLUSIONS. We conclude that percutaneous balloon commissurotomy and surgical closed commissurotomy result in comparable hemodynamic improvement that is sustained through 8 months of follow-up. 