Predictive Performance of the Aggregate Index of Systemic Inflammation for Contrast-Induced Nephropathy After PCI in...

Background and Objectives: This study aimed to evaluate the predictive value of the Aggregate Index of Systemic Inflammation (AISI) for contrast-induced nephropathy (CIN) development in elderly patients with acute coronary syndrome (ACS) undergoing PCI. Materials and Methods: The study included consecutive patients aged ≥65 years who underwent PCI for ACS between January 2022 and January 2024. The primary endpoint was the occurrence of CIN, defined as an increase in serum creatinine ≥0.5 mg/dL or ≥25% from baseline within 48-72 h after PCI. The AISI was calculated for each patient. Results: A total of 437 patients (mean age 73.7 ± 7.2 years, 64.5% male) were included. The overall incidence of CIN was 25.6%. Patients who developed CIN were older, more frequently female, and had lower left ventricular ejection fraction and albumin but higher SYNTAX I scores and baseline creatinine (all p < 0.001). AISI demonstrated a significant predictive accuracy for CIN (AUC: 0.709, 95% CI: 0.647-0.771, p < 0.001), which was statistically comparable to the Mehran score (AUC: 0.744, p = 0.095). In multivariable analysis, AISI emerged as a strong independent predictor of CIN (OR: 1.345, 95% CI: 1.123-1.437, p < 0.001), alongside SYNTAX I scores, baseline creatinine, and serum albumin. Notably, AISI retained its independent predictive power even when adjusted for the Mehran score (OR: 1.276, p < 0.001). Conclusions: AISI independently predicts CIN in elderly patients with ACS undergoing PCI. Its superior discriminative ability compared with single hematologic markers highlights the importance of systemic inflammatory burden in CIN pathogenesis. Incorporating AISI into pre-procedural assessment may improve risk stratification and preventive management in this high-risk population.