Supplementary Material for: Functional Mitral Regurgitation following Successful Living Donor Kidney Transplant: The VINTAGE Study

Introduction
Functional mitral regurgitation (FMR) is prevalent in CKD patients, but few studies have evaluated the effect of kidney transplant (KT) on FMR. This study aimed to clarify KT's effect on FMR.

Methods
This study included 115 living donor KT recipients (2012-2023). Primary outcome was change in FMR severity (5 categories: none to severe) based on echocardiographic findings before and 1 year post-KT. Aortic regurgitation (AR) severity and changes in left atrial diameter (LAD), left ventricular end-diastolic dimension (LVDd), ANP, and BNP levels were also assessed. Change in FMR and AR severity was assessed using Wilcoxon signed-rank tests. Multivariable logistic regression models were used to identify factors associated with the worsening of FMR and AR.

Results
At baseline, 76.5% had trivial FMR; 22.6% had mild/moderate/severe FMR. One year post-KT, moderate/severe FMR disappeared. Overall, FMR improved in 19.1%, remained unchanged in 73.1%, and worsened in 7.8%. FMR severity distribution significantly changed (P=0.004). Reductions in LAD/LVDd aligned with decreased ANP/BNP. Multivariable analysis identified acute ABMR as an independent factor for worsening FMR (OR 4.02, 95% CI 1.81–8.91, P < 0.001). No significant AR improvement was observed (P=0.377). A history of arrhythmia (OR 2.68, 95% CI 1.28–5.64, P = 0.009) and stroke (OR 2.27, 95% CI 1.12–4.59, P = 0.023) were identified as an independent factor for worsening AR.

Conclusions
KT is associated with an improvement in FMR among patients with kidney failure (KF). This is likely due to LA/LV reverse remodeling from reduced volume/pressure overload. However, this benefit may diminish with graft dysfunction (e.g., acute rejection). Conversely, KT is not associated with an improvement in AR. Our findings highlight another important cardioprotective benefit of successful KT. Further prospective studies are needed to better understand this association.