Stages of MS Stage Definition Valve Anatomy Valve Hemodynamics Hemodynamic Consequences Symptoms A At risk of MS Mild valve doming during diastole Normal transmitral flow velocity None None B Progressive MS Rheumatic valve changes with commissural fusion and diastolic doming of the mitral valve leaflets Planimetered mitral valve area Increased transmitral flow velocities Mitral valve area >1.5 cm2 Diastolic pressure half-time Mild to moderate LA enlargement Normal pulmonary pressure at rest None C Asymptomatic severe MS Rheumatic valve changes with commissural fusion and diastolic doming of the mitral valve leaflets Planimetered mitral valve area Mitral valve area 1.5 cm2 Diastolic pressure half-time Severe LA enlargement Elevated PASP >50 mm Hg None D Symptomatic severe MS Rheumatic valve changes with commissural fusion and diastolic doming of the mitral valve leaflets Planimetered mitral valve area Mitral valve area 1.5 cm2 Diastolic pressure half-time Severe LA enlargement Elevated PASP >50 mm Hg Decreased exercise tolerance Exertional dyspnea The transmitral mean pressure gradient should be obtained to further determine the hemodynamic effect of the MS and is usually >5 mm Hg to 10 mm Hg in severe MS; however, because of the variability of the mean pressure gradient with heart rate and forward flow, it has not been included in the criteria for severity. LA indicates left atrial; MS, mitral stenosis; and PASP, pulmonary artery systolic pressure. CLINICAL STATEMENTS AND GUIDELINES and suitability for PMBC. If PMBC is being considered, a TEE can further evaluate the presence and severity of concomitant MR and rule out LA thrombus. Recommendation-Specific Supportive Text 1. 