Balloon mitral commissurotomy (BMC) was performed in 113 patients. Of these patients, 27 (24%) (25 women and 2 men, aged 49 +/- 13 years) had recurrent mitral stenosis 13 +/- 6 years (range 5 to 29) after surgical commissurotomy. Eleven patients (41%) were considered at high risk for surgery. BMC resulted in an increase in mitral valve area from 1.1 +/- 0.3 to 1.9 +/- 0.7 cm2 (p < 0.0001), and a decrease in mean mitral gradient from 16 +/- 7 to 6 +/- 3 mm Hg (p < 0.0001). An optimal result of BMC (increase in valve area > or = 25% with a post-BMC valve area > or = 1.5 cm2) was obtained in 18 patients (67%). The results did not differ from those observed in the 86 patients of our entire series without prior surgical commissurotomy. Patients with an optimal result of BMC had a more recent surgical commissurotomy and lesser morphologic alterations of the mitral valve than did those with a nonoptimal result. Patients with echocardiographic scores < 10 had an 80% success rate of BMC; however, this rate decreased to 29% for those with scores > or = 10. One patient (4%) died from a cerebrovascular accident. Clinical follow-up at 1 year showed persistent clinical improvement in 89% of patients with an optimal result of BMC; 72% were in New York Heart Association class I and 17% in class II.(ABSTRACT TRUNCATED AT 250 WORDS)