Recommendations for Intervention for Chronic Primary MR Referenced studies that support the recommendations are summarized in Online Data Supplement 30. COR LOE Recommendations In symptomatic patients with severe primary MR (Stage D), mitral valve intervention is recommended irrespective of LV systolic In asymptomatic patients with severe primary MR and LV systolic dysfunction (LVEF 60%, LVESD 40 mm) (Stage C2), mitral valve surgery is recommended.3 10 In patients with severe primary MR for whom surgery is indicated, mitral valve repair is recommended in preference to mitral valve replacement when the anatomic cause of MR is degenerative disease, if a successful and durable repair is possible.11 15 In asymptomatic patients with severe primary MR and normal LV systolic function (LVEF 60% and LVESD 40 mm) (Stage C1), mitral valve repair is reasonable when the likelihood of a successful and durable repair without residual MR is >95% with an expected mortality rate of <1%, when it can be performed at a Primary or Comprehensive In asymptomatic patients with severe primary MR and normal LV systolic function (LVEF >60% and LVESD <40 mm) (Stage C1) but with a progressive increase in LV size or decrease in EF on 3 serial imaging studies, mitral valve surgery may be considered irrespective of the probability of a successful and durable repair.16 In severely symptomatic patients (NYHA class III or IV) with primary severe MR and high or prohibitive surgical risk, transcatheter edge-to- edge repair (TEER) is reasonable if mitral valve anatomy is favorable for the repair procedure and patient life expectancy is at least 1 year.17,18 In symptomatic patients with severe primary MR attributable to rheumatic valve disease, mitral valve repair may be considered at a Comprehensive Valve Center by an experienced team when surgical treatment is indicated, if a durable and successful repair is likely.19 3: Harm B-NR In patients with severe primary MR where leaflet pathology is limited to less than one half the posterior leaflet, mitral valve replacement should not be performed unless mitral valve repair has been attempted at a Primary or Comprehensive Valve Center and Synopsis Anterior and/or bileaflet primary mitral valve disease re- quires a complex and extensive repair,20,23 26 and durabil- ity of the repair is less certain than for simple posterior leaflet intervention. 