Balloon mitral commissurotomy after previous surgical commissurotomy

Background. Mitral restenosis after surgical mitral commissurotomy often occurs within 5-15 years, necessitating a repeat procedure. Balloon mitral commissurotomy (BMC) has been advocated as an alternative to repeat surgery for mitral restenosis. Methods and Results. The purposes of this study are to determine the short- and intermediate-term outcomes of patients undergoing BMC after previous surgical commissurotomy, to compare these patients with those undergoing balloon mitral commissurotomy as an initial procedure, and to elucidate the multivariate determinants of acute procedural and clinical outcome. Of 738 patients undergoing BMC as part of the National Heart, Lung, and Blood Institute Balloon Valvuloplasty Registry, 133 underwent BMC after previous surgical mitral commissurotomy. Prospective data obtained included demographic, hemodynamic, echocardiographic, and clinical follow-up. BMC after previous surgical commissurotomy produced a significant reduction in transvalvular gradient from 13±5 to 6±3 mm Hg (p<0.0001) and an increase in mitral valve area from 1.0±0.3 to 1.8±0.8 cm² (p<0.0001). BMC as an initial procedure increased valve area from 1.0±0.4 to 2.0±0.8 cm² (p<0.0001) (p=0.03 versus prior surgery). Baseline characteristics including mitral valve echo score were similar for both groups. Comparing 6-month status in patients with prior surgery to those without, 80% versus 90% were New York Heart Association (NYHA) functional class I or II (p=0.004). Mortality was similar. In patients with previous mitral valve surgery, multivariate predictors of improvement in 6-month clinical status included the experience of the center (p=0.006), lower echocardiographic score (p=0.001), and lower left ventricular end-diastolic pressure p=0.008). Multivariate determinants of a final mitral valve area ≥1.5 cm² were a lower baseline NYHA functional class (p=0.003) and lower mitral valve echocardiographic score (p-0.008). Conclusions. BMC after previous surgical mitral commissurotomy results in similar hemodynamic changes as in patients undergoing BMC as an initial procedure. Symptomatic improvement at 6 months is slightly less frequent in prior commissurotomy patients. Patients with favorable valvular morphology and preserved left ventricular function who undergo BMC in experienced centers are most likely to achieve symptomatic improvement after previous surgical commissurotomy. In general, BMC is an effective treatment for mitral restenosis after previous surgical commissurotomy.