#1688 Association of Baseline Serum Activin Levels with Left Atrial Diameter at 5 Years Post-Kidney Transplantation: Results from the KNOW-KT

Abstract Background and Aims Serum activin A inhibits muscle growth, promotes apoptosis, and impairs heart function. However, the role of serum activin remains unclear in kidney transplant patients, where cardiovascular complications are a significant cause of morbidity and mortality. In this multicenter, observational cohort study, we investigated a potential association of pre-transplant serum activin levels with the left atrial (LA) diameter, an indicator of diastolic burden and a predictor of cardiovascular complications, to indirectly assess the impact of pre-transplant activin levels on heart function in kidney transplant patients. Method Overall, 602 kidney transplant patients from KNOW-KT (Korean cohort study for outcome in patients with kidney transplantation) were analyzed. Activin levels were measured at baseline immediately before kidney transplantation (KT). The primary outcome was the LA diameter that was measured by transthoracic echocardiography at 5 years after KT. Results The mean age of study population was 45.4 years and 221 (46.7%) patients were men. Pre-transplant serum activin levels were 718.4 ± 363.2 (mean ± standard deviation). When activin levels were divided into categorical variables according to the median value, the ejection fraction of LV showed a lower tendency in the high-activin group (64.3 ± 7.0) compared to the low-activin group (65.3 ± 6.2); however, there was no statistical significance (P=0.069). LV diastolic dimension was significantly higher in the high-activin group (47.3 ± 5.3) compared to the low-activin group (46.3 ± 5.5) (P=0.021). Notably, the post-transplant LA diameter was 37.0 ± 7.0 mm in the low-activin group and 39.1 ± 6.5 mm in the high-activin group, showing a significant difference (P<0.001). The multivariate linear regression coefficient for association between activin groups and LA diameter was 1.08 (95% confidence interval [CI], 0.67-2.10, P=0.037). In an additional logistic regression analysis of LA diameter groups, the high activin group was significantly associated with the high LA diameters compared to the low-activin group in multivariate analysis (adjusted odds ratio [OR], 2.04; 95% CI, 1.34-3.09, P=0.001). When activin levels were used as a continuous variable, adjusted ORs of activin for high LA diameters were 1.29 (95% CI, 1.04-1.60, P=0.018). Conclusion Pre-transplant serum activin levels were independently associated with a higher post-transplant LA diameter, suggesting that activin may negatively affect heart functions in kidney transplant patients. Therefore, activin may be a potential prognostic and therapeutic target in kidney transplant patients.