Association of the Remnant Cholesterol Inflammatory Index with Acute Kidney Injury After Primary Percutaneous Coronary Intervention in Patients with ST-Segment Elevation Myocardial Infarction: A Retrospective Observational Study
Abstract
Background Contrast-induced acute kidney injury (CI-AKI) remains a clinically important complication after percutaneous coronary intervention (PCI), particularly in patients with ST-segment elevation myocardial infarction (STEMI). The remnant cholesterol inflammatory index (RCII), integrating remnant cholesterol (RC) and C-reactive protein (CRP), may reflect both residual lipid burden and systemic inflammatory activation. This study aimed to evaluate the association between RCII and CI-AKI in patients with STEMI undergoing PCI. Methods This single-center retrospective observational study included 771 consecutive patients with STEMI who underwent primary PCI between May 2023 and May 2026. The primary outcome was in-hospital CI-AKI. Multivariable logistic regression, restricted cubic spline (RCS) analysis, receiver operating characteristic (ROC) analysis, integrated discrimination improvement (IDI), and continuous net reclassification improvement (NRI) were performed. Results CI-AKI occurred in 85 patients (11.0%). Patients with high RCII had a significantly higher incidence of CI-AKI than those with low RCII (15.32% vs 6.74%, P<0.001). In multivariable logistic regression analysis, RCII remained independently associated with CI-AKI after adjustment for relevant covariates (adjusted odds ratio=1.026, 95% confidence interval: 1.007–1.045, P=0.007). RCS analysis demonstrated a significant nonlinear dose–response relationship between RCII and CI-AKI. The addition of RCII to the baseline clinical model resulted in significant improvements in IDI (0.027, P=0.015) and continuous NRI (0.283, P=0.007), whereas the increase in AUC was modest and not statistically significant. Conclusion Elevated RCII was independently associated with an increased risk of CI-AKI in patients with STEMI undergoing PCI. RCII may serve as a simple and readily available biomarker to assist in risk stratification.