Admission Serum Total Brain-Derived Neurotrophic Factor and Angiographic No-Reflow in Non-ST-Segment Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Background and Objectives: Angiographic no-reflow (NRF) after percutaneous coronary intervention (PCI) reflects impaired microvascular reperfusion despite successful treatment of the epicardial culprit lesion. Brain-derived neurotrophic factor (BDNF) is a neurotrophin involved in endothelial signaling, platelet biology, inflammation, and angiogenesis. Its relationship with NRF in non-ST-segment elevation myocardial infarction (NSTEMI) remains insufficiently characterized. Materials and Methods: This single-center prospective observational cohort study included 700 consecutive NSTEMI patients undergoing culprit-lesion PCI. Admission serum total BDNF was measured before PCI using a standardized enzyme-linked immunosorbent assay protocol. Angiographic NRF was defined as final thrombolysis in myocardial infarction (TIMI) flow <3 and/or TIMI 3 flow with myocardial blush grade (MBG) 0–1 in the absence of residual stenosis, dissection, severe spasm, or other mechanical obstruction. Four sequential logistic regression models were used to evaluate the stability of the association between BDNF and NRF: Model 1 adjusted for clinical variables; Model 2 further adjusted for laboratory and inflammatory variables; Model 3 further adjusted for cardiac injury and functional variables; and Model 4 further adjusted for angiographic and procedural variables. Discrimination, calibration, reclassification, decision-curve analysis, and internal validation were assessed. Results: NRF occurred in 114 of 700 patients (16.3%). Serum total BDNF was higher in the NRF group than in the reflow group [555 (465–688) vs. 386 (292–496) pg/mL, p < 0.001]. BDNF remained independently associated with NRF across sequential models: Model 1 OR 1.67 per 100 pg/mL (95% CI 1.43–1.96), Model 2 OR 1.49 (95% CI 1.24–1.79), Model 3 OR 1.41 (95% CI 1.16–1.72), and Model 4 OR 1.31 (95% CI 1.07–1.60). The BDNF-only AUC was 0.787, while the final BDNF-enriched Model 4 reached an AUC of 0.866. The optimism-corrected bootstrap AUC was 0.852 and the 10-fold cross-validated AUC was 0.845. Conclusions: Higher admission serum total BDNF was independently associated with angiographic NRF in NSTEMI patients undergoing PCI and improved risk discrimination when added to clinical, biochemical, cardiac, and angiographic predictors. These findings suggest that serum total BDNF may reflect a context-dependent biomarker signal related to acute thrombo-inflammatory, platelet-associated, and microvascular injury pathways; however, the observed incremental value was modest and requires external validation.