Insights Into the Histopathology of Intracoronary Stent Thrombosis
What are histopathological findings on evaluation of thrombus in patients presenting with coronary stent thrombosis (ST)?
This was an analysis of data collected by the PRESTIGE (Prevention of Late Stent Thrombosis by an Interdisciplinary Global European Effort) consortium. Patients presenting with ST and undergoing thrombus aspiration were eligible for inclusion. Patients were categorized according to timing of ST – as early (<30 days) and late (>30 days) post stent implantation and type of stent at the index procedure (drug-eluting stent [DES] or bare-metal stent [BMS]). Immunohistochemistry was performed to identify leukocyte subsets, prothrombotic neutrophic extracellular traps (NETs), erythrocytes, platelets, and fibrinogen.
Overall, thrombus from 253 patients was available for histological analysis: 79 (31.2%) thrombus specimens were from patients presenting with early ST, and 174 (68.8%) from late ST. 166 (65.6%) thrombus samples were from DES and 79 (31.2%) from BMS. Central components were platelet-rich thrombus, fibrin/fibrinogen fragments, trapped erythrocytes, and inflammatory cells. Mean platelet coverage was 57% of thrombus area. Both early and late ST were characterized by leukocyte infiltrations; neutrophils were the most prominent subset. Leukocyte counts were significantly higher in ST patients, compared to a control group of patients with thrombus aspiration in spontaneous myocardial infarction. Eosinophils were present in all stent types, and there was no significant difference in the number of eosinophils according to the timing of ST. Higher numbers of eosinophils were seen in patients with very late ST in sirolimus- and everolimus-eluting stents.
Histologic thrombus analysis from patients presenting with ST demonstrates heterogeneous morphology, recruitment of leukocytes (particularly neutrophils), and eosinophil accumulation in both BMS and DES thrombus specimens.
This is a significant contribution toward understanding the histopathology of thrombus formation in patients presenting with ST. In the largest analysis of its kind to date, the authors demonstrate the heterogeneity of the thrombus specimens, corroborating the known role of platelet activation and drawing attention to the predominance of leukocytes (neutrophils, in particular). Eosinophil accumulation implicates the role of allergic reactions in the development of ST. As the authors posit, their findings ‘suggest that immune cells could represent an important target for the prevention of ST in future experimental research and clinical trials.’
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