The aim of this study was to assess late results of percutaneous mitral commissurotomy (PMC) in calcific mitral stenosis and to identify predictors to improve patient selection. We analyzed 422 patients who underwent PMC for calcific mitral stenosis. The extent of calcium was graded from 1 to 4 by fluoroscopy: 227 patients (53%) were graded 1, 125 (30%) graded 2, 55 graded 3 (13%), and 15 graded 4 (4%). The procedure failed in 15 patients, used a single balloon in 11, a double balloon in 126, and the Inoue balloon in 270. In-hospital mortality was 1.2%. Good immediate results (valve area >/=1.5 cm(2) without mitral regurgitation >2/4), were obtained in 321 patients (76%). Multivariate analysis identified 5 predictors of good immediate results: a younger age (p = 0.0004), a lesser degree of stenosis (p = 0.0005), a smaller extent of calcium (p = 0.04), the use of the Inoue balloon (p = 0.015), and a larger effective balloon dilating area (p = 0.006). Good functional results, defined as survival with no further intervention and in New York Heart Association class I or II, were 36 +/- 4% at 8 years. The predictors of good functional results after good immediate results were a younger age (p = 0.04), a lower pre-PMC New York Heart Association class (p <0.0001), sinus rhythm (p = 0.0006), a smaller extent of calcium (p = 0.02), and a lower gradient after PMC (p <0.0001). Despite a frequent deterioration on follow-up after PMC for calcific mitral stenosis, the predictive analysis suggests that PMC may be useful in deferring surgery in selected patients with mild to moderate calcific deposits, who have otherwise favorable characteristics.