The onset of symptoms that results from severe MR worsens prognosis even when LV function appears to be normal,1,2 and the negative prognosis extends even to mild symptoms.2 Thus, the onset of symp- toms is an indication for prompt mitral valve surgery. 2. The goal of therapy in MR is to correct it before the onset of LV systolic dysfunction and its sub- sequent adverse effect on patient outcomes. The ideal time for mitral valve surgery is when the patient s LV approaches but has not yet reached the parameters that indicate systolic dysfunction Because symptoms do not always coincide with LV dys- function, imaging surveillance is used to plan surgery before severe dysfunction has occurred. If moderate LV dysfunction is already present, prog- nosis is worse after mitral valve operation.5 7,9,10,16 Thus, further delay (although symptoms are absent) will lead to greater LV dysfunction and a CLINICAL STATEMENTS AND GUIDELINES still worse prognosis. Because the loading condi- tions in MR allow continued late ejection into a lower-impedance LA, a higher cutoff for nor- mal LVEF is used in MR than in other types of heart disease. Although it is clearly inadvisable to allow patients LV function to deteriorate beyond the benchmarks of an LVEF 60% or LVESD 40 mm, some recovery of LV function can still occur even if these thresholds have been crossed.5,32 3. Repair success increases with surgical volume and expertise, which is a principle guiding surgical However, mitral valve replacement is preferable to a poor repair. 