13 Indexed left atrial volume predicts adverse outcomes independent of the severity of ischaemic mitral regurgitation-a cohort study of 1000 patients following acute myocardial infarction

Abstract

Background Ischaemic mitral regurgitation (IMR) is associated with left atrial (LA) dilatation. In patients with primary MR, LA enlargement is an independent predictor of mortality following medical management and mitral valve surgery. The prognostic significance of LA dilatation in IMR post-myocardial infarction (MI) has not been studied. Purpose To determine the impact of LA dilatation on mortality in patients with IMR. Methods 1000 consecutive patients admitted to the Queen Elizabeth Hospital Birmingham with MI who underwent percutaneous coronary intervention were included. Early inpatient TTE was performed within 24-48 hours by accredited echocardiographers using standard multiparametric quantification of IMR, including proximal isovelocity surface area (PISA), effective regurgitant orifice (EROA), vena contracta (VC), and regurgitant volume (RVol). LA size was measured by the recommended biplane method for calculation of LA volume and indexed to body surface area (Mosteller). Analysis was performed on patients with indexed LA volume (LAVi) above and below 34ml/m2 (defined as the upper limit of normal in European Cardiovascular Imaging guidelines). Results MR was observed in 294/1000 patients (29.4%) post-MI, graded as mild (76%), moderate (21%) and severe (3%). A total of 275/294 (94%) had complete chamber volume data. LA dilatation (LAVi > 34ml/m2) was seen in 124 (45%) patients while 151/275 (55%) had normal LA volume (LAVi Although patients with LAVi > 34ml/m2 were older (76+/-11 years vs 70+/-12; p 34ml/m2 accounted for 60% of this mortality. Conclusion IMR patients with LA dilatation have significantly higher mortality than those with normal LA volume. Those with LAVi > 34ml/m2 account for 60% of all IMR mortality, despite fewer ST elevation infarcts and smaller troponin rise. Future studies of intervention for IMR should consider LA dilatation as a potential marker of outcome. Conflict of Interest None