Previous studies have demonstrated that mitral regurgitation (MR) greatly influenced long-term outcome after surgical mitral commissurotomy in pts with mitral stenosis. However, this issue has not been addressed after balloon mitral valvotomy (BMV). We therefore examined 6 year follow-up (FU) data in 69 pts who presented MR assessed by angiography before BMV (group 1), and compared the results with 75 pts who had no MR (group 2). Mean FU period was 27±20 mo in group 1 and 33±23 mo in group 2 (p=NS). Comparison of pts baseline characteristics, mitral valve area (MVA) before and after BMV and FU results between the groups were:Clinical ProfileGroup 1Group 2p-valueAge (yr)57±1345±160.0001Sex: M/F80%/20%17%/83%NSNYHA-FC: III-IV90%81%NSEcho score>822%12%NSFluoroscopic Ca2+87%60%0.001A.F56%19%0.0001Pre 2D MVA (cm2)1.06±0.30100±027NSPost 2D MVA (cm2)1.71±0.351.88±0.410.01FU NYHA class I51%88%0.0001Cardiac events (CE)28%9%<0.01CE=stroke, repeat BMV, mitral valve replacement (MVR), and deathComparison of 6 year CE-free and MVR-free actuarial survival rates were:Gr 1/Gr 21-yr2-yr3-yr4-yr5-yr6-yrp-valueCE-free (%)87/9479/9273/9065/9059/9049/790.002MVR-free (%)93/9689/9682/9678/9678/9665/840.01Hazard risk ratio by Cox regression analysis was 3.7 (95% CI: 1.5-8.9) times greater for CE (p<0.01), and 4.0 (1.2–12.7) times greater for MVR (p<0.05) at FU in group 1 than in group 2.(1) MR before BMV increases risk for late CE, particularly requiring MVR in the early FU. (2) Pts with MR appears to be older with calcified valves and AF, and to obtain smaller MVA post BMV, all of which may exacerbate the poor later outcome. (3) Half of such pts may still derive long-term benefits from BMV.