Clinical, functional and prognostic implications of severe atrial dilation in secondary mitral regurgitation

OBJECTIVE: Atrial dilation is known to be a poor prognostic indicator. However, its clinical, functional and prognostic implications have not been thoroughly explored in secondary mitral regurgitation (SMR). We sought to describe the implications of severe atrial dilation (SAD) in SMR. METHODS: We included all adult patients with severe SMR due to left ventricle dysfunction (with no organic mitral valve disease) who underwent transthoracic echocardiography between January 2012 and March 2021 at our institution. The concomitant presence of severe left atrial (LA) dilation (>48 mL/m(2)) defined SADMR (SAD in SMR), and these patients were compared with those without SAD. RESULTS: A total of 2011 patients were included (mean age 70% and 41% females), with 71% having SADMR. MR severity and ejection fraction were similar between both groups. Patients with SADMR were older, less females and had more diabetes, but similar rates of atrial fibrillation. Mechanistically, they had lower A wave velocity (0.61 vs 0.72 cm/sec, p<0.001) and more impaired LA reservoir strain (9.7% vs 15.5%, p<0.001). Geometrically, SADMR had shallower leaflets’ angulations, lower tenting height, larger annuli and smaller leaflet length/annular diameter ratios (all p<0.001). They underwent fewer MV interventions, although these were associated with better outcomes (log-rank p<0.001). Over the study period, SAD was an independent predictor of mortality (HR 1.26, p=0.04). CONCLUSION: SADMR is associated with specific mechanistic and functional alterations and confers a worse prognosis.