Abstract Background The precise triggers for arterial plaque rupture and the underlying pathophysiology of thrombogenesis remain elusive. Polymorphonuclear neutrophils (PMN), particularly their formation of Neutrophil Extracellular Traps (NETs), have garnered attention in the context of coronary atherothrombosis. This study sought to explore the association of NETs burden with clinical and angiographic characteristics in ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (pPCI) and thrombus aspiration (TA). Methods This study included 336 consecutive STEMI patients undergoing pPCI and TA. Aspirated thrombi underwent histological analysis and NETs quantification via immunohistochemistry. Potential associations of clinical variables and angiographic outcomes with NETs burden were assessed. Results Manual TA was selectively performed in 72 cases with increased thrombotic burden and 60 thrombi were suitable for analysis. Most thrombi specimens displayed lytic features (63%) and almost three out of four specimens were identified as white thrombi. Increased NETs burden was significantly associated with prolonged pain-to-balloon time (>300 minutes) OR=10.29 (95% CI 2.11-42.22, p=0.001) and stress-induced hyperglycemia (SIH) OR=6.58 (95% CI 1.23-52.63, p=0.04) after multivariate regression analysis. Additionally, distal embolization (DE), a predictor of adverse outcomes, was more frequent among patients with an elevated NETs burden OR=16.9 (95% CI 4.23-44.52, p<0.001). Conversely, no significant association between NETs burden and final TIMI flow=3 was observed. Conclusion Elevated NETs burden in STEMI thrombi is linked to delayed reperfusion, SIH and increased risk of DE. Further research is needed to elucidate the role of NETs as a potential therapeutic target in acute atherothrombosis.