Percutaneous transvenous mitral commissurotomy has emerged as an effective nonsurgical technique for the treatment of patients with symptomatic mitral stenosis. This report highlights the immediate and long-term follow-up results of this procedure in an unselected cohort of patients with rheumatic mitral stenosis from a single center. It was performed in a total of 4,850 patients using double balloon in 320 (6.6%), flow-guided Inoue balloon technique in 4,374 (90.2%), and metallic valvulotome in 156 (3.2%) patients. Their age range was 6.5-72 years (mean, 27.2 +/- 11.2 years) and 1,552 (32%) patients were under 20 years of age. Atrial fibrillation was present in 702 (14.5%) patients. No patient was rejected on the basis of echocardiographic score using the Wilkins criteria. Echocardiographic score of > or = 8 was present in 1,632 (33.6%) patients, of which 103 (2.1%) had densely calcified (Wilkins score 4+) valve. A detailed clinical and echocardiographic (two-dimensional, continuous-wave Doppler and color-flow imaging) assessment was done at every 3 months for the first year and at 6-month interval thereafter. The procedure was technically successful in 4,838 (99.8%) patients but optimal result was achieved in 4,408 (90.9%) patients with an increase in mitral valve area (MVA) from 0.7 +/- 0.2 to 1.9 +/- 0.3 cm(2) (P < 0.001) and a reduction in mean transmitral gradient from 29.5 +/- 7.0 to 5.9 +/- 2.1 mm Hg (P < 0.001). The mean left atrial pressure decreased from 32.1 +/- 9.8 to 13.1 +/- 6.2 mm Hg (P < 0.001). Although there was no statistically significant difference in the MVA achieved between de novo and restenosed valves (1.9 +/- 0.3 and 1.8 +/- 0.2 cm(2), respectively; P > 0.05), or between noncalcific and calcific valves (2.0 +/- 0.3 and 1.8 +/- 0.2 cm(2), respectively; P > 0.05), on the whole MVA obtained after percutaneous transvenous mitral commissurotomy was less in restenosed and calcific valves. Ten (0.20%) patients had cardiac tamponade during the procedure. Mitral regurgitation appeared or worsened in 2,038 (42%) patients, of which 68 (1.4%) developed severe mitral regurgitation. Urgent mitral valve replacement was carried out in 52 (1.1%) of these patients. Data of 3,500 patients followed over a period of 94 +/- 41 months (range, 12-166 months) revealed MVA of 1.7 +/- 0.3 cm(2). Elective mitral valve replacement was done in 34 (0.97%) patients. Mitral restenosis was seen in 168 (4.8%) patients, of which 133 (3.8%) were having recurrence of class III or more symptoms. Thus, percutaneous transvenous mitral commissurotomy is an effective and safe procedure with gratifying results in high percentage of patients. The benefits are sustained in a majority of these patients on long-term follow-up. It should be considered as the treatment of choice in patients with rheumatic mitral stenosis of all age groups.