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. CLINICAL STATEMENTS AND GUIDELINES An elevated pulmonary arterial resistance before intervention is associated with RV dysfunction and TR after the procedure.40 42 Thus, PMBC may prevent the adverse consequences of irreversible pulmonary hypertension if it can be performed with a high success rate and low risk in patients who are developing pulmonary hyper- tension. Correction of the MR before irreversible changes occur can be curative. Thus, in chronic primary MR, MR is the disease. 4. The new onset of AF may be an indication for pro- ceeding with PMBC in the asymptomatic patient with a favorable valve morphology for several rea- sons. First, AF may be the equivalent of symptom onset, signifying that rheumatic MS is resulting in progressive LA damage. Second, AF increases the risk of thromboembolic events in patients with rheumatic MS. In addition, a shortened diastolic filling interval with AF and a rapid ventricular response further increase LV pressure. Finally, the presence of AF is associated with worse outcomes in patients with rheumatic MS and with subop- timal results after PMBC.43 In theory, lowering a high LA pressure after PMBC might be beneficial in restoring normal sinus rhythm. Although there is no randomized trial to prove the effectiveness of intervening early, there is a documented improve- ment in P-wave dispersion after PMBC, which may affect the ability to restore normal sinus rhythm.15 5. Some patients have symptoms from rheumatic MS even with a mitral valve area >1.5 cm2 and a resting mean transmitral gradient <10 mmHg. 