Correlation between Syndecan-1 in Inter Category of RACHS-1 Score and Immediate Clinical Outcomes

Background: Low cardiac output syndrome (LCOS) is a frequent and serious complication after pediatric cardiac surgery. Endothelial glycocalyx (EG) degradation, indicated by elevated syndecan-1, contributes to microvascular dysfunction and postoperative instability. The relationship between syndecan-1 dynamics and surgical risk categories remains unclear. Objective: To examine the association between perioperative syndecan-1 levels and clinical outcomes across Risk Adjustment for Congenital Heart Surgery (RACHS-1) categories. Methods: We analyzed 106 children (RACHS-1 categories 2-4) undergoing elective cardiac surgery with cardiopulmonary bypass (CPB). Syndecan-1 was measured at baseline (T0), 4 h (T4), and 72 h (T72). Outcomes included LCOS, vasoactive inotropic score (VIS), Pediatric Logistic Organ Dysfunction (PELOD-2), pediatric intensive care unit (PICU) stay, and mortality. Analyses used Kruskal-Wallis, Bonferroni post hoc tests, Spearman correlation, and multivariable regression adjusted for CPB duration, cross-clamp time, and pre-PICU status. Results: Syndecan-1 differed significantly across RACHS groups at T0 (p = 0.044) and T72 (p = 0.015). RACHS score was weakly correlated but significant with syndecan-1 at T72 (r = 0.238, p = 0.019) and decline from T4-T72 (r = 0.249, p = 0.013), indicating delayed recovery at higher risk. RACHS-4 patients had the highest VIS and PELOD-2 scores and longer PICU stay. In adjusted models, RACHS-3 was associated with higher syndecan-1 at T72 (β = +51.9, p = 0.016), higher VIS 0-4 h (β = +4.9, p = 0.008), and increased LCOS risk (OR 5.99, 95 CI 1.61-25.70, p = 0.010). RACHS-4 showed greater organ dysfunction but LCOS risk was attenuated (OR 0.19 vs. RACHS-3, p = 0.035). Mortality was highest in RACHS-4 (17.6) but not statistically significant (p = 0.368). Conclusion: Higher RACHS categories are linked with delayed EG recovery, greater vasoactive support, and more severe organ dysfunction. Syndecan-1 kinetics at 72 h, alongside VIS and LCOS, may serve as adjunctive markers for postoperative risk stratification in pediatric cardiac surgery.