Of 280 patients treated by balloon mitral commissurotomy (BMC) between 1987 and 1991, 28 (10%) were > or = 70 years old. Two patients with associated significant aortic stenosis were excluded from the study. Older patients more often were in New York Heart Association class III or IV (84 vs 67%; p < 0.007) and atrial fibrillation (61 vs 36%; p < 0.0001), and had a higher echocardiographic score (9.3 +/- 2 vs 8 +/- 1.6; p < 0.0004) and a lower baseline cardiac index (2.1 +/- 0.6 vs 2.4 +/- 0.6 liters/min/m2; p < 0.03) than younger ones. Baseline mean pulmonary pressure (37 +/- 11 vs 34 +/- 12 mm Hg), transmitral gradient (14 +/- 4 vs 14 +/- 5 mm Hg) and valve area (1.0 +/- 0.4 vs 1.1 +/- 0.3 cm2) were not different between older and younger patients (p = NS). Acute complications during the procedure (including cardiac perforation, embolism, severe mitral regurgitation and surgical atrial shunt), and 30-day mortality after BMC were more frequent in older than younger patients (27 vs 9% [p < 0.01], and 12 vs 0.8% [p < 0.005], respectively). A complete success, defined as a mitral valve area increase > 25% and postmitral valve area > 1.5 cm2 was obtained in 16 of the 22 older patients (72%) with the completed procedure (compared with 81% of younger ones; p = 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)