Percutaneous transvenous mitral commissurotomy (PTMC) was performed in 350 patients. Of these patients, 51 (15%) (30 women and 21 men, aged 32 +/- 11 years) had restenosis 11 +/- 4 years following surgical valvotomy. Forty (79%) patients were in New York Heart Association (NYHA) class III and 11 (21%) were in class IV. PTMC resulted in an increase in mitral valve area from 0.82 +/- 0.3 to 1.9 +/- 0.2 cm2 (p < 0.001), an increase in cardiac index from 1.9 +/- 0.4 to 2.8 +/- 0.5 l/min/m2 (p < 0.001), and a decrease in mean transmitral gradients from 29 +/- 4 to 6 +/- 4 mmHg (p < 0.001). The results did not differ from those observed in 299 patients without prior surgical valvotomy. On univariate analysis, the subvalvular fibrosis, assessed angiographically, and the duration from prior surgery were not found to influence the overall outcome. At 24 weeks, 46 of 48 (96%) patients in whom clinical follow-up was available, were found to be in NYHA class I and 2 (4%) patients were in class II. Thus, PTMC is a safe and effective procedure for patients with mitral restenosis following surgical valvotomy.