Association and Discriminative Performance of Lipid-Derived and Metabolic Atherogenic Indices in Coronary Slow Flow

Abstract

Introduction: Coronary slow flow (CSF) is increasingly interpreted as a functional abnormality of the coronary microcirculation and has been associated with metabolic imbalance and unfavorable cardiovascular profiles. Recently proposed metabolic markers, including the atherogenic index of plasma (AIP) and the triglyceride–glucose (TyG) index, have attracted attention as easily applicable indicators that reflect atherogenic lipid burden and insulin resistance. Nevertheless, evidence comparing the relationship between these indices and CSF remains scarce. Methods: In this retrospective analysis, 132 patients diagnosed with CSF by coronary angiography and 175 individuals with normal coronary flow were evaluated. CSF was identified using corrected thrombolysis in myocardial infarction (TIMI) frame count measurements. AIP, TyG, and modified TyG (Mod-TyG) indices were derived from fasting biochemical data. Associations with CSF were examined using correlation analysis, receiver operating characteristic (ROC) curve analysis, and multivariable logistic regression models. Results: Patients with CSF demonstrated significantly higher AIP and TyG values, whereas Mod-TyG did not differ between the groups. AIP demonstrated the most robust correlation with corrected TIMI frame count values, particularly concerning the left anterior descending artery. ROC analysis revealed a better discriminative ability for AIP than TyG (AUC 0.685 vs. 0.634), whereas Mod-TyG was non-discriminatory. In the multivariate analysis, AIP and TyG remained independent predictors of CSF, along with smoking and hypertension. Discussion and Conclusion: Lipid-driven atherogenic burden appears to play an important role in CSF. Among the evaluated indices, AIP demonstrated the strongest discriminative performance and the closest association with flow delay, supporting its potential clinical utility in CSF assessment.