Recruitment of leukocytes is a hallmark of stent thrombosis, according to results from a PRESTIGE substudy presented Aug. 30 during ESC Congress 2015 in London, and simultaneously published in European Heart Journal. Investigators say their findings suggest that immune cell mediated thrombotic processes may be a realistic target for novel therapies to prevent stent thrombosis.

The PRESTIGE substudy included patients with stent thrombosis and undergoing thrombus aspiration at nine centers in Europe between 2010 and 2014. Overall, 253 thrombus specimens were analyzed histologically. Of these, 79 (31.2 percent) were from patients presenting with early stent thrombosis and 174 (68.8 percent) were from late stent thrombosis, while 79 (31.2 percent) were from bare metal stents, 166 (65.6 percent) were from drug-eluting stents and eight (3.2 percent) were from stents of an unknown type.

Study investigators found that the thrombus specimens had heterogeneous morphology with platelet-rich thrombus and fibrin/fibrinogen fragments being most abundant. Leukocyte infiltrations were hallmarks of both early and late state thrombosis with neutrophils representing the most prominent subset. Neutrophils were found in similar amounts in early and late stent thrombosis. However, leukocyte counts were significantly higher compared with a control group of patients with thrombus aspiration in spontaneous myocardial infarction.

Additionally, neutrophil extracellular traps (NETs) were observed in 23 percent of samples, while eosinophils were present in all stent types, with higher numbers in patients with late stent thrombosis sirolimus-eluting and everolimus-eluting stents. "The presence of NETs supports their pathophysiological relevance in stent thrombosis, while eosinophil recruitment suggests an allergic component to the process of stent thrombosis," said principal investigator Steffen Massberg, MD, director of the Department of Cardiology at the Ludwig-Maximilians University, Munich, Germany.

"Although some pathological processes associated with stent thrombosis have been identified, the triggering mechanisms remain incompletely understood, and the influence of factors such as timing of ST after the procedure, stent type or polymer coating is poorly characterized," explains Julia Riegger, MD, also from Ludwig-Maximilians University. She noted that moving forward, greater detail is needed in particular around the potential role of immune cells and related extracellular components.

Keywords: ESC Congress, Europe, Stents, Thrombosis

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