Left atrial function as a determinant of symptoms in patients with severe degenerative mitral regurgitation

Abstract Funding Acknowledgements Type of funding sources: None. Background Understanding the pathophisiology of symptoms onset in degenerative mitral regurgitation may be helpful in the management of asymptomatic patients. Left atrium (LA) is far from simply being a passive connection chamber between mitral valve and pulmonary circulation, and the role of left atrial function as a predictor of symptoms onset has not yet been evaluated. The increase in atrial pressure that causes elevation of pulmonary capillary pressures and the onset of dyspnoea may be driven by the reduction of left atrial compliance, which can be assessed by peak atrial longitudinal strain (PALS) derived from speckle tracking echocardiography. Aim To assess the role of left atrial function as a determinant of symptoms in patients with severe degenerative MR. Methods We analysed retrospectively all patients affected by severe degenerative MR evaluated for cardiac surgery between May 2019 and July 2022 at IRCCS San Raffaele Hospital. The cohort was divided in symptomatic (NYHA >I) and asymptomatic (NYHA =I) patients. A comprehensive assessment of LA function was performed including pulmonary venous blood flow, LA ejection fraction, LA fractional atrial change, and PALS. Patients with atrial fibrillation during echocardiographic evaluation, left ventricular disfunction and more than mild left heart valvulopathy associated with MR were excluded. Results The final study population consisted of 408 patients. The grade of MR, assessed by multiparametric approach, was not different between the two groups. Age, history of coronary artery disease, dyslipidaemia, hypertension and history of atrial fibrillation were found to be predictive on symptomatology. Fractional area change (OR: 0.89; CI:0.87–0.91, p <0.001), atrial ejection fraction (OR: 0.92, CI= 0.90–0.94, p <0.001), atrial volume(OR: 1.04, CI: 1.02–1.05, p<0.001), pulmonary artery systolic pressure(OR:1.09, CI:1.06–1.13, p<0.001) and longitudinal atrial strain (OR:0.88, CI:0.85–0.90, p<0.001) but not EROA ( OR:1.06, CI: 0.63–2.30, p = 0.8) were found to be predictive. On multivariate logistic regression, only indexed biplane LA volume (OR: 1.02, CI 1.00–1.07, p = 0.035) and PALS (OR: 1.02, CI: 0.87–0.94, p<0.001) were found to be predictive. The best PALS threshold to identify symptomatic patients was 22% (OR: 3.3, SE 67%, SP 87%). Conclusions LA function is a determinant of symptoms in severe degenerative MR. The reduction of PALS appears to be a predictor of symptoms and a value of PALS < 22% identified symptomatic patients with 85% specificity and 67% sensitivity.