Preprocedural Serum Albumin and Early Contrast-Associated Acute Kidney Injury After Elective Carotid Artery Stenting: Incremental Prognostic Information Beyond the PCI-Derived Mehran Score

Background/Objectives: We assessed whether preprocedural serum albumin adds prognostic information to the PCI-derived Mehran score for early contrast-associated acute kidney injury (CA-AKI) after elective carotid artery stenting (CAS). Methods: This single-centre retrospective cohort included 121 consecutive elective patients (January 2020–April 2026). The primary model combined the reconstructed Mehran score with albumin < 3.5 g/dL, a conventional threshold fixed in advance. Because the score uses actual contrast volume, the combined model applies only after CAS. The outcome used KDIGO serum creatinine thresholds (≥0.3 mg/dL or ≥1.5 times baseline) from routine second-day testing. Internal validation used 1000 bootstrap resamples. Results: Early CA-AKI occurred in 32 patients (26.4%). Adjusted odds ratios were 1.35 per Mehran point (95% CI 1.13–1.60) and 11.68 for albumin < 3.5 g/dL (95% CI 4.14–32.97). AUC increased from 0.768 to 0.865 (95% CI 0.794–0.937; likelihood ratio χ2 = 24.58, p < 0.001). Corrected AUC, calibration slope, and Brier score were 0.860, 0.96, and 0.132. In exploratory decision curves (20% threshold), corrected net benefit was 0.168 for the combined model and 0.133 for Mehran alone. Conclusions: Low preprocedural albumin added prognostic information to the PCI-derived score and may help select patients for closer renal surveillance after CAS. External validation and prospective impact studies are needed before clinical use.