A total of 318 consecutive patients with mitral stenosis underwent percutaneous mitral valvotomy at our institution from 1987 to 1993. Of those, 98 patients had color Doppler echocardiographic studies performed before, 24 hours after, and late after the intervention. On the basis of color Doppler echocardiographic grading of tricuspid regurgitation, 32 patients (32%; mean age 57 +/- 15 years) had significant (moderate or severe) tricuspid regurgitation before the intervention and were the subject of this study. The follow-up study was performed 18.4 +/- 13 months after the procedure. Successful percutaneous mitral valvotomy (> or = 1.5 cm2 valve area or > or = 50% increase after valvotomy) with no restenosis at follow-up was achieved in 20 patients. Tricuspid regurgitation decreased by one grade (from severe to moderate) in only four subjects in this group and in none of the 12 patients who did not meet the criteria for successful percutaneous mitral valvotomy or who had restenosis. Thus tricuspid regurgitation did not improve in 88% of all patients studied. On average, no significant change was observed in the ratio of maximal tricuspid regurgitant jet area to right atrial area 24 hours after percutaneous mitral valvotomy and at late follow-up (37% vs .33% vs 34%, respectively) or in any of the right heart dimensions, even in patients who underwent successful percutaneous mitral valvotomy. Right ventricular systolic pressure also did not change significantly on average in those patients (46 +/- 15 versus 42 +/- 14 versus 48 +/- 18 mm Hg, respectively). However, right ventricular dimensions did not decrease and tricuspid regurgitation did not resolve even in a subgroup of patients in whom right ventricular systolic pressure fell by more than 10 mm Hg (up to 41 mm Hg).