Coronary angiography-derived index of microcirculatory resistance associated with contrast-induced acute kidney injury in patients with STEMI.

Background: More than half of ST-segment elevation myocardial infarction (STEMI) patients have coronary microcirculatory dysfunction (CMD) after percutaneous coronary intervention (PCI). This study aimed to explore the role of CMD in the occurrence of contrast-induced acute kidney injury (CI-AKI) in patients with STEMI. Methods: This was a single-centre retrospective clinical observational study. Coronary angiography-derived index of microcirculatory resistance (caIMR) was measured and used to assess CMD. Regression analysis was used to identify risk factors for CI-AKI. Restricted cubic splines (RCS) was employed to examine the dose-response relationship between caIMR and CI-AKI. The predictive accuracy of the models was assessed with net reclassification index (NRI), and integrated discrimination improvement (IDI). Results: This study included 745 patients, the incidence of CI-AKI was 10.6% (79/745). Multivariate logistic regression identified caIMR (OR = 1.072, 95% CI: 1.051-1.094) as an independent predictor of CI-AKI. RCS analysis indicated a linear dose-response relationship between caIMR and CI-AKI. Receiver operating characteristic (ROC) analysis demonstrated that the areas under the curve for caIMR was 0.725, the optimal cutoff value was 25.95 U. Integration of caIMR could significantly improve the risk model for CI-AKI in STEMI patients (NRI = 0.721, IDI = 0.102, Conclusions: Elevated caIMR is an independent risk factor for the development of CI-AKI after PCI in STEMI patients. Integrating caIMR significantly improves the risk model for CI-AKI.