Atherogenic Index of Plasma Across the Angiographic Spectrum of Coronary Stenosis: Implications for Risk Stratification

Abstract

Objective: The atherogenic index of plasma (AIP), derived from the logarithmic ratio of triglycerides to high-density lipoprotein cholesterol, has been proposed as a marker of atherogenic lipid burden. Although previous studies have linked AIP to coronary artery disease, its association with progressively increasing angiographic stenosis and its contribution beyond routinely available clinical variables remain uncertain. Methods: We retrospectively evaluated 490 patients who underwent elective coronary angiography at a single tertiary centre. According to the highest degree of luminal narrowing, patients were classified into four predefined stenosis categories (<30%, 30–50%, 51–69%, and ≥70%). Ordinal logistic regression was used to examine the relationship between AIP and stenosis severity after sequential adjustment for clinical variables. Model discrimination, reclassification, calibration, and internal validation were assessed using receiver operating characteristic (ROC) analysis, continuous net reclassification improvement (cNRI), integrated discrimination improvement (IDI), and bootstrap resampling. Results: AIP values were higher in every lesion-bearing category than in the <30% group and were highest in the ≥70% group (median 0.4 to 0.6, p < 0.001). After adjustment for age, sex, diabetes mellitus, hypertension, and red cell distribution width, higher AIP remained associated with more advanced coronary stenosis (OR 2.66, 95% CI 2.18–3.25; p < 0.001). Incorporating AIP into the clinical model improved overall model performance, yielding an area under the curve (AUC) of 0.781 (optimism-corrected AUC 0.768) together with significant gains in both cNRI (0.764) and IDI (0.101) (both p < 0.001). In contrast, red cell distribution width (RDW) and the haemoglobin-albumin-lymphocyte-platelet (HALP) score were not independently associated with stenosis severity after multivariable adjustment. Conclusion: Among patients undergoing elective coronary angiography, higher AIP values were consistently associated with more extensive angiographic coronary stenosis. Adding AIP to conventional clinical variables improved risk classification, whereas RDW and HALP offered limited additional information after adjustment. These findings support further evaluation of AIP as an easily obtainable biomarker for angiographic risk assessment in prospective external validation studies.