Prevalence and prognostic implications of chronic kidney disease in patients with atrial functional mitral regurgitation

Background Atrial functional mitral regurgitation (AFMR) is increasingly recognized as a distinct mitral regurgitation subtype; the prognostic impact of coexisting chronic kidney disease (CKD) remains unclear. Methods Data from 989 patients enrolled in the multicenter REVEAL-AFMR registry were analyzed. Coexisting CKD was defined as reduced estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m 2 . Patients were further classified by CKD severity as stage 1 + 2 (eGFR ≥60), stage 3a (eGFR ≥45 and < 60), stage 3b (eGFR ≥30 and < 45), and stage 4 + 5 (eGFR <30). The primary endpoint was a composite of cardiovascular death and heart failure hospitalization. Kaplan-Meier and multivariable Cox regression analyses were performed to assess the primary endpoint. Results Coexisting CKD was present in 429 of 989 patients (43.4%). Lower eGFR was associated with more advanced mitral regurgitation (MR), higher BNP levels, and more severe heart failure symptoms. Over a median follow-up of 1002 days, 181 patients (18.3%) experienced the primary endpoint. The cumulative incidence of the primary endpoint increased stepwise across CKD stages (log-rank P < 0.001). In multivariable analysis, CKD stage remained independently associated with adverse outcomes (HR 1.26; 95% CI 1.09–1.46; P = 0.002). This association was consistent across MR severity strata, with no significant interaction between MR severity and CKD stage. Conclusion Among conservatively managed patients with AFMR, CKD is common in AFMR, and CKD stage is independently associated with worse outcomes in a graded manner, irrespective of MR severity. Renal function assessment may improve AFMR risk stratification.