Mitral valve surgery is an established therapy for rheumatic MS, with the preferred approach being commissurotomy (either closed, where the valve is opened blindly through the LA or LV, or open, which allows more extensive surgery under direct visual- ization) when anatomy is favorable.31 36 However, in the presence of severe valvular thickening and subvalvular fibrosis with leaflet tethering, mitral valve replacement may be the best option. In addi- tion to those who have suboptimal valve anatomy (or failed PMBC), patients with moderate or severe TR may also have a better outcome with a surgi- cal approach that includes tricuspid valve repair.37 Patients undergoing surgical commissurotomy at centers with a high level of expertise may have better long-term outcomes than those undergoing Because the natural history of rheumatic MS is one of slow progression over decades, sur- gery should be delayed until the patient has severe limiting symptoms (NYHA class III or IV), particu- larly if mitral valve repair is contemplated. asymptomatic will do well for years without inter- vention, an elevation of pulmonary artery pressure is an indication that there is progressive elevation of LA pressure affecting the pulmonary circulation. An elevated pulmonary pressure can be assessed by Doppler echocardiography. Although there may be a decrease in pulmonary pressure after relief of the rheumatic MS,38 some patients will have developed intrinsic pulmonary vascular disease, as evidenced by a poorer long-term survival rate in patients who have pulmonary hypertension before Figure 7. Intervention for MS. Colors correspond to Table 2. *Repair, commis- surotomy, or valve replacement. AF indicates atrial fibrillation; CVC, Comprehensive Valve Center; MR, mitral regurgitation; MS, mitral stenosis; MV, mitral valve; MVA, mitral valve area; NYHA, New York Heart Association; PASP, pulmonary artery systolic pressure; and PMBC, percutaneous mitral balloon commissurotomy. 