Left Atrial Size Is a Potent Predictor of Mortality in Mitral Regurgitation Due to Flail Leaflets

BACKGROUND: Left atrium (LA) enlargement is common in organic mitral regurgitation (MR) and is an emerging prognostic indicator. However, outcome implications of LA enlargement have not been analyzed in the context of routine clinical practice and in a multicenter study. METHODS AND RESULTS: The Mitral Regurgitation International DAtabase (MIDA) registry enrolls patients with organic MR due to flail leaflets, diagnosed in routine clinical practice, in 5 US and European centers. We investigated the relation between LA diameter and mortality under medical treatment and after mitral surgery in 788 patients in sinus rhythm (64±12 years; median LA, 48 43 to 52 mm). LA diameter was independently associated with survival after diagnosis (hazard ratio, 1.08 1.04 to 1.12 per 1 mm increment). Compared with patients with LA 0.20). Mitral surgery was associated with greater survival benefit in patients with LA ≥55 mm compared with LA <55 mm (P for interaction, 0.008). CONCLUSIONS: In MR caused by flail leaflets, LA diameter ≥55 mm is associated with increased mortality under medical treatment, independent of the presence of symptoms or left ventricular dysfunction.