Pre-PCI C-reactive protein–triglyceride glucose index and angiographic no-reflow or slow flow in acute myocardial infarction: a single-centre retrospective study

Background Angiographic no-reflow or slow flow after percutaneous coronary intervention (PCI) is linked to impaired myocardial reperfusion in acute myocardial infarction (AMI). The C-reactive protein–triglyceride glucose index (CTI) combines information on systemic inflammation and insulin resistance. This study examined the association of pre-PCI CTI with immediate post-PCI no-reflow or slow flow and assessed its additional predictive information beyond routine clinical variables. Methods This single-centre retrospective study included 429 patients with AMI who underwent PCI between January 2023 and January 2025. All variables used to calculate CTI were collected before PCI. Immediate post-PCI Thrombolysis in Myocardial Infarction (TIMI) flow was assessed by two experienced interventional cardiologists who were blinded during adjudication. TIMI grade 3 was classified as normal flow, and TIMI grades 0–2 as no-reflow or slow flow after excluding mechanical obstruction. Multivariable logistic regression, restricted cubic splines, receiver operating characteristic curves, bootstrap internal validation, and exploratory incremental-value and subgroup analyses were performed. Results Among 429 patients, 102 had no-reflow or slow flow. Pre-PCI CTI was higher in patients with the outcome than in those with normal flow (10.57 ± 0.96 versus 9.39 ± 0.86). After adjustment for age, sex, ST-elevation myocardial infarction, diabetes, hypertension, current smoking, estimated glomerular filtration rate, and left ventricular ejection fraction, each 1-unit increase in CTI was associated with higher odds of no-reflow or slow flow (odds ratio 3.34, 95% confidence interval 2.30–5.05; P < 0.001). The association was nonlinear (P for nonlinearity = 0.003). CTI alone had an area under the curve (AUC) of 0.830 (95% confidence interval 0.778–0.883). Adding CTI to the clinical model increased the AUC from 0.850 to 0.889 (difference 0.039, 95% confidence interval 0.010–0.067; P = 0.008). The optimism-corrected AUC was 0.875 (95% confidence interval 0.837–0.917). Diabetes did not show evidence of effect modification (P for interaction = 0.533). Conclusions Higher pre-PCI CTI was associated with immediate angiographic no-reflow or slow flow in this retrospective AMI cohort and added predictive information to a clinical model. The cut-off, reclassification measures, decision curves, and diabetes subgroup findings remain exploratory. Bootstrap internal validation cannot replace validation in an independent external cohort.