Categorization of MR severity as mild, moderate, or severe depends on data quality and integration of these parameters in conjunction with other clinical evidence. ERO indicates effective regurgitant orifice; IE, infective endocarditis; LA, left atrium/atrial; LV, left ventricular; LVEF, left ventricular ejection fraction; LVESD; left ventricular end-systolic dimension; and MR, mitral regurgitation. CLINICAL STATEMENTS AND GUIDELINES Recommendation-Specific Supportive Text 1. The onset of symptoms in severe MR (dyspnea on exertion, orthopnea, or declining exercise tolerance) is an indication for mitral intervention even if LV function is preserved.2 Symptoms are the culmina- tion of the pathophysiology of MR and may indicate changes in LV or LA compliance; increase in pulmo- nary artery pressure; decrease in RV function; or the coexistence of TR. Therefore, symptoms add patho- physiological data not readily available from imag- ing, if other confounding factors can be excluded. Furthermore, there is no evidence that treatment with diuretics or other therapies that might relieve symptoms changes the prognostic effect of symp- tom onset. Once symptoms have occurred and are caused by MR, mitral valve surgery will improve the natural history even if medication has led to improve- ment. Repeat TTE at the time of symptom onset is indicated to confirm that symptoms are likely attrib- utable to MR or its effect on the LV, which in turn supports surgical correction.1 The new onset of AF is also an indication for repeat TTE to look for changes in severity of MR and the status of the LV. 7.2.2.3. Diagnostic Testing: Routine Follow-Up Recommendations for Diagnostic Testing: Routine Follow-Up for Chronic Primary MR Referenced studies that support the recommendations are summarized in Online Data Supplement 27. 