BackgroundStent thrombosis (ST) is a rare but serious complication following percutaneous coronary intervention. Analysis of thrombus composition from patients undergoing catheter thrombectomy may provide important insights into the pathological processes leading to thrombus formation. We performed a large-scale multicentre study to evaluate thrombus specimens in patients with ST across Europe.MethodsPatients presenting with ST and undergoing thrombus aspiration were eligible for inclusion. Thrombus collection was performed according to a standardized protocol and specimens were analysed histologically at a core laboratory. Serial tissue cross sections were stained with haematoxylin–eosin (H&E), Carstairs and Luna. Immunohistochemistry was performed to identify leukocyte subsets, prothrombotic neutrophil extracellular traps (NETs), erythrocytes, platelets, and fibrinogen.ResultsOverall 253 thrombus specimens were analysed; 79 (31.2%) from patients presenting with early ST, 174 (68.8%) from late ST; 79 (31.2%) were from bare metal stents, 166 (65.6%) from drug-eluting stents, 8 (3.2%) were from stents of unknown type. Thrombus specimens displayed heterogeneous morphology with platelet-rich thrombus and fibrin/fibrinogen fragments most abundant; mean platelet coverage was 57% of thrombus area. Leukocyte infiltrations were hallmarks of both early and late ST (early: 2260 ± 1550 per mm2 vs. late: 2485 ± 1778 per mm2; P = 0.44); neutrophils represented the most prominent subset (early: 1364 ± 923 per mm2 vs. late: 1428 ± 1023 per mm2; P = 0.81). Leukocyte counts were significantly higher compared with a control group of patients with thrombus aspiration in spontaneous myocardial infarction. Neutrophil extracellular traps were observed in 23% of samples. Eosinophils were present in all stent types, with higher numbers in patients with late ST in sirolimus-and everolimus-eluting stents.ConclusionIn a large-scale study of histological thrombus analysis from patients presenting with ST, thrombus specimens displayed heterogeneous morphology. Recruitment of leukocytes, particularly neutrophils, appears to be a hallmark of ST. The presence of NETs supports their pathophysiological relevance. Eosinophil recruitment suggests an allergic component to the process of ST.
Among patients with acute STEMI undergoing emergent PCI, the MGuard micronet mesh-covered stent compared with conventional metal stents resulted in superior rates of epicardial coronary flow and complete ST-segment resolution. A larger randomized trial is warranted to determine whether these benefits result in reduced infarct size and/or improved clinical outcomes. (Safety and Efficacy Study of MGuard Stent After a Heart Attack [MASTER]; NCT01368471).
Blood flow restoration after primary percutaneous coronary intervention (pPCI) in patients with acute myocardial infarction (AMI) may not always be achieved and could be complicated by the no-reflow phenomenon (NRP). The aim of the current study was to assess the frequency of thrombus aspirations (TAs) and NRPs in patients with AMI and treated with pPCI based on the data collected during a 5-year period in the national ORPKI registry, as well as the frequency of periprocedural strokes and predictors of TA and NRP. This retrospective analysis was performed on prospectively collected data gathered in the Polish National Registry of Percutaneous Coronary Interventions (ORPKI), which covered the period between January 2014 and December 2018, and included 200,991 patients treated due to AMI out of 535,857 patients treated using PCI. Among them, 16,777 patients underwent TA. TA was mainly used in the STEMI subgroup of 14,207 patients (84.8%). The frequency of NRP among AMI patients in the thrombectomy group was 2.75% and in the non-thrombectomy group 0.82%. Predictors of TA and NRP were also assessed using multivariate analysis. The percentage of patients treated with pPCI and with PCI alone increased significantly in all of the three selected groups of patients from 88.7% to 94.3% in the AMI group (p < 0.001), from 82.3% to 90.3% in the STEMI subgroup (p < 0.001), and from 96.3% to 98.2% in the NSTEMI subgroup (p < 0.001) during the analysed period. NRP occurred more often in the thrombectomy group for the NSTEMI (0.58% vs. 3.07%, p < 0.05) and STEMI (1.06% vs. 2.69%, p < 0.05) subgroups. Periprocedural stroke occurred more often in the thrombectomy group in comparison to the non-thrombectomy group with AMI (0.03% vs. 0.01%, p < 0.05) and the NSTEMI (0.16% vs. 0.02%, p < 0.05). In conclusion, the frequency of TA has been experiencing a steady decline in recent years, regardless of AMI type, among patients treated with pPCI.
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