Clinical and echocardiographic parameters associated with outcomes in patients with moderate secondary mitral regurgitation

Background Significant secondary mitral regurgitation (SMR) is known to be associated with worse prognosis. However, data focusing specifically on moderate SMR and associated risk factors are lacking. In the present study, clinical and echocardiographic parameters associated with outcomes were evaluated in a large cohort of patients with moderate SMR. Methods Patients with moderate SMR were retrospectively included and stratified by New York Heart Association (NYHA) class and specific aetiology (atrial SMR (aSMR) or ventricular SMR (vSMR)) with a further classification of vSMR based on left ventricular ejection fraction (LVEF) ≥40% or <40%. The primary endpoint was all-cause mortality and the secondary endpoint was the composite of all-cause mortality and heart failure (HF) events. Results Of the total 1061 patients with moderate SMR (age 69±11 years, 59% male) included, 854 (80%) were in NYHA class I−II and 207 (20%) were in NYHA class III−IV. Regarding the aetiology, 352 (33%) had aSMR and 709 (67%) had vSMR, of which 329 (46%) had LVEF ≥40% and 380 (54%) had LVEF <40%. During a median follow-up of 82 (IQR 55–115) months, 397 (37%) died and 539 (51%) patients had HF events or died. On multivariable analysis, NYHA class III−IV (HR 1.578; 95% CI 1.244 to 2.002, p<0.001) and SMR aetiology were independently associated with both endpoints. Specifically, compared to aSMR, vSMR with LVEF ≥40% had a HR of 1.528 (95% CI 1.108 to 2.106, p=0.010) and vSMR with LVEF <40% had a HR of 1.960 (95% CI 1.434 to 2.679, p<0.001). To further support these findings, patients were matched for (1) NYHA class and (2) SMR aetiology by propensity scores including age, sex, diabetes, chronic obstructive pulmonary disease, renal function, left atrial volume index, NYHA class (only for SMR aetiology matching), LVEF, SMR aetiology (only for NYHA class matching), tricuspid regurgitation severity and right ventricular pulmonary artery coupling index. After matching, NYHA class and SMR aetiology remained associated with both outcomes (for both: log rank p<0.050). Conclusion In patients with moderate SMR, distinction in SMR aetiology and assessment of symptoms are important independent determinants of outcome.