Journal of Thrombosis and Thrombolysis

Thrombelastography (TEG) measures coagulation in venous blood. We hypothesized that TEG, by reflecting clot subtype and ex vivo fibrinolysis, might predict fibrinolytic response to tPA as reflected by rapid clinical improvement or hemorrhagic transformation of the infarct. 171 acute ischemic stroke patients treated with tPA were prospectively enrolled. Venous blood for TEG was drawn before and 10 min after tPA bolus. We measured rapid clinical improvement (RCI = 8 point improvement on NIHSS or total NIHSS of 0, 1 at 36 h), Hemorrhagic transformation (HT = any blood on imaging within 36 h), and hyperdense middle cerebral artery sign (HDMCA = biomarker for erythrocyte-rich clot). Multivariable regression models compared TEG parameters after adjusting for potential confounders. No differences in pre- or post-tPA TEG were found between patients with or without RCI. Also, there was no correlation between TEG and HDMCA. Clotting was slightly prolonged in patients with HT (p = 0.046). We failed to find a robust association between TEG and clinical response to tPA. It is likely that arterial clot lysis is determined by factors unrelated to coagulation status as measured by TEG in the venous circulation. It is unlikely that TEG will be useful to predict clinical response to tPA, but may help predict bleeding.

Coronavirus disease 2019 (Covid-19) is associated with a high incidence of venous and arterial thromboembolic events. Currently, there are no clinical or laboratory markers that predict thrombotic risk. Circulating immature platelets are hyper-reactive platelets, which are associated with arterial thrombotic events. The aim of this study was to assess whether the proportion of circulating immature platelets is associated with disease severity in Covid-19 patients. Patients admitted with Covid-19 disease were prospectively assessed. Immature platelet count (IPC) and immature platelet fraction (IPF) were measured at admission and at additional time points during the hospital course using the Sysmex XN-3000 auto-analyzer. A total of 136 consecutive patients with Covid-19 were recruited [mean age 60 ± 19 years, 49% woman, 56 (41%) had mild-moderate disease and 80 (59%) had severe disease at presentation]. The median IPF% was higher in patients with severe compared to mild-moderate disease [5.8 (3.9–8.7) vs. 4.2 (2.73–6.45), respectively, p = 0.01]. The maximal IPC value was also higher in patients with severe disease [15 (10.03–21.56), vs 10.9 (IQR 6.79–15.62), respectively, p = 0.001]. Increased IPC was associated with increased length of hospital stay. Patients with severe Covid-19 have higher levels of IPF than patients with mild-moderate disease. IPF may serve as a prognostic marker for disease severity in Covid-19 patients.

Studies of patients with COVID-19 have demonstrated markedly dysregulated coagulation and a high risk of morbid arterial and venous thrombotic events. Elevated levels of blood neutrophils and neutrophil extracellular traps (NETs) have recently been described in patients with COVID-19. However, their potential role in COVID-19-associated thrombosis remains incompletely understood. In order to elucidate the potential role of hyperactive neutrophils and NET release in COVID-19-associated thrombosis, we conducted a case–control study of patients hospitalized with COVID-19 who developed thrombosis, as compared with gender- and age-matched COVID-19 patients without clinical thrombosis. We found that remnants of NETs (cell-free DNA, myeloperoxidase-DNA complexes, and citrullinated histone H3) and neutrophil-derived S100A8/A9 (calprotectin) in patient sera were associated with higher risk of morbid thrombotic events in spite of prophylactic anticoagulation. These observations underscore the need for urgent investigation into the potential relationship between NETs and unrelenting thrombosis in COVID-19, as well as novel approaches for thrombosis prevention.

Pulmonary embolectomy is a treatment option in selected patients with high-risk pulmonary embolism (PE). Efficiency of thrombus degradation in PE largely depends on the architecture of its fibrin network, however little is known about its determinants. We present the case of a 56-year-old woman with high-risk PE and proximal deep-vein thrombosis, whose thrombotic material removed during embolectomy from the right atrium and pulmonary (lobar and segmental) arteries has been studied using scanning electron microscopy (SEM). SEM images showed that distally located thrombi are richer in densely-packed fibrin fibers and contain more white cells and less erythrocytes than the proximal ones and the atrial thrombus. Fibrin fibers alignment along the flow vector was observed in the thrombi removed from high-velocity flow pulmonary arteries, and not in the atrial thrombus. The content of denser fibrin network and platelet aggregates was increased in segmental thromboemboli. Our findings describe the relation between thrombus architecture and location, and might help to elucidate thrombus resistance to anticoagulant therapy in some PE patients.

The impact of antithrombin III activity (AT-III) on prophylactic enoxaparin anti-factor Xa concentration (anti-Xa) is unknown in high-risk trauma patients. So too is the optimal anti-Xa-adjusted enoxaparin dosage. This prospective, randomized, pilot study sought to explore the association between AT-III and anti-Xa goal attainment and to preliminarily evaluate two enoxaparin dosage adjustment strategies in patients with subprophylactic anti-Xa. Adult trauma patients with Risk Assessment Profile (RAP) ≥ 5 prescribed enoxaparin 30 mg subcutaneously every 12 h were eligible. AT-III and anti-Xa were drawn 8 h after the third enoxaparin dose and compared between patients with anti-Xa ≥ 0.1 IU/mL (goal; control group) or anti-Xa < 0.1 IU/mL (subprophylactic; intervention group). The primary outcome was difference in baseline AT-III. Subsequently, intervention group patients underwent 1:1 randomization to either enoxaparin 40 mg every 12 h (up to 50 mg every 12 h if repeat anti-Xa < 0.1 IU/mL) (enox12) or enoxaparin 30 mg every 8 h (enox8) with repeat anti-Xa assessments. The proportion of patients achieving goal anti-Xa after dosage adjustment were compared. A total of 103 patients were included. Anti-Xa was subprophylactic in 50.5%. Baseline AT-III (median [IQR]) was 87% [80–98%] in control patients versus 82% [71–96%] in intervention patients (p = 0.092). Goal trough anti-Xa was achieved on first assessment in 38.1% enox12 versus 50% enox8 patients (p = 0.67), 84.6% versus 53.3% on second assessment (p = 0.11), and 100% vs. 54.5% on third trough assessment (p = 0.045). AT-III activity did not differ between high-risk trauma patients with goal and subprophylactic enoxaparin anti-Xa concentrations, although future investigation is warranted. Enoxaparin dose adjustment rather than frequency adjustment may be associated with a higher proportion of patients achieving goal anti-Xa over time.

Venous thrombosis (VT) is a complex multi-factorial disease and a major health concern worldwide. Its clinical implications include deep vein thrombosis (DVT) and pulmonary embolism (PE). VT pathogenesis involves intricate interplay of various coagulants and anti-coagulants. Growing evidences from epidemiological studies have shown that many non-coding microRNAs play significant regulatory role in VT pathogenesis by modulating expressions of large number of gene involved in blood coagulation. Present study aimed to investigate the effect of human micro RNA (hsa-miR)-320a antagonist on thrombus formation in VT. Surgery was performed on Sprague–Dawley (SD) rats, wherein the inferior vena cava (IVC) was ligated to introduce DVT. Animals were divided into four groups (n = 5 in each group); Sham controls (Sham), IVC ligated-DVT (DVT), IVC ligated-DVT + transfection reagent (DVT-NC) and IVC ligated-DVT + miR320a antagonist (DVT-miR-320a antagonist). IVC was dissected after 6 h and 24 h of surgery to estimate thrombus weight and coagulatory parameters such as levels of D-dimer, clotting time and bleeding time. Also, ELISA based biochemical assays were formed to assess toxicity of miRNA antagonist in animals. Our experimental analysis demonstrated that there was a marked reduction in size of thrombus in hsa-miR-320a antagonist treated animals, both at 6 h and 24 h. There was a marked reduction in D-dimer levels in hsa-miR-320a antagonist treated animals. Also, blood clotting time was delayed and bleeding time was increased significantly in hsa-miR-320a antagonist treated rats compared to the non-treated and Sham rats. There was no sign of toxicity in treated group compared to control animals. Hsa-miR-320a antagonist could be promising therapeutic target for management of VT.

Có rất ít nghiên cứu so sánh đột quỵ thiếu máu cục bộ cấp tính ở tuần hoàn trước (AC) và tuần hoàn sau (PC). Nghiên cứu của chúng tôi nhằm đánh giá các đặc điểm khác biệt của đột quỵ AC và PC liên quan đến các yếu tố lâm sàng, nguy cơ mạch máu, sinh bệnh học và kết quả sau các thủ thuật nội mạch. Nghiên cứu đa trung tâm triển vọng này đã ghi nhận 873 bệnh nhân bị tắc mạch cấp tính lớn ở đột quỵ tuần hoàn trước (ACS) và đột quỵ tuần hoàn sau (PCS). Những bệnh nhân đã trải qua các thủ thuật nội mạch được đưa vào nghiên cứu này. Sự khác biệt trong ACS và PCS về các đặc điểm cơ bản, chảy máu nội sọ sau phẫu thuật và kết quả đã được đánh giá. Tổng có 741 bệnh nhân được đưa vào phân tích dữ liệu. Thrombolysis tĩnh mạch (31,5%), rung nhĩ (22,7%) và thrombectomy stent (82,4%) được ghi nhận thường xuyên hơn ở bệnh nhân ACS. Trong khi điểm số NIHSS cao hơn, tăng huyết áp (67,6%) và bóng thông mạch (20,7%) phổ biến hơn ở bệnh nhân PCS. Chảy máu nội sọ có triệu chứng thường gặp hơn ở ACS (7,4% so với 2,8%). Tuy nhiên, kết quả theo dõi sau 3 tháng tốt hơn ở ACS với tỷ lệ độc lập chức năng cao hơn và tỷ lệ tử vong thấp hơn so với PCS (46,8% so với 30,3% và 16,4% so với 33,8%, tương ứng, P < 0,01). Trong nghiên cứu lớn này, có sự khác biệt đáng kể trong sinh bệnh học của đột quỵ và quy trình điều trị giữa ACS và PCS, ảnh hưởng đến kết quả lâm sàng. Những phát hiện này có thể dẫn đến các quy trình lâm sàng và chiến lược điều trị được điều chỉnh nhằm cải thiện tiên lượng ở cả hai nhóm.

Complexing recombinant DNA with cationic liposomes is a convenient means of introducing foreign genes into cells (lipofection) and could potentially form the basis for genetically modifying diseased blood vessels in patients. The mechanism of lipofection is incompletely understood, but it is recognized that the degree of successful gene transfer is highly dependent on cell type. We have transfected primary cultures of human vascular smooth muscle cells with a plasmid expressing either firefly luciferase (Luc) or nuclearlocalized β-galactosidase (NL-β-gal). Cells were derived from either normal human internal mammary arteries, fragments of primary atherosclerotic plaque, or fragments of restenotic lesion. Concurrent lipofection of rabbit vascular smooth muscle cells and NIH 3T3 cells was performed as well. Compared with NIH 3T3 cells, expression in human vascular smooth muscle cells was markedly reduced: In cells derived from internal mammary artery, Luc expression, normalized for protein content, was 123-fold lower than in NIH 3T3 cells, while the proportion of cells expressing NL-β-gal was 30-fold lower. Luc expression in cells derived from restenotic tissue was significantly greater than from cells derived from primary plaque. Within a given population of cells, the mitotic index of cells expressing the recombinant gene was significantly higher than the mitotic index for the total population of cells (p < 0.05). Finally, cotransfection experiments, in which lipofection of smooth muscle cells was performed using genes for NL-β-gal and for human growth hormone, showed that among positive transfectants a high proportion of cells (23–36%) coexpressed both genes. Thus, the efficiency of successful lipofection in human vascular smooth muscle cells in vitro is low. Transfection appears to be preferentially facilitated in cells derived from restenotic tissue and specific properties of smooth muscle cells, including growth rates, appear to be critical for successful transfection. Further elucidation of cell properties that promote transfection is required to augment the efficiency of liposome-mediated gene transfer in human vascular cells.

Background: Acute coronary syndromes, characterized by the rupture of unstable plaque and the subsequent thrombotic process involving platelets, have been increasing in relative frequency. The central role of platelet activation has long been noticed in this pathophysiology; hence, many therapies have been directed against it. In this study, we have aimed to search prospectively the value of mean platelet volume (MPV), which is a simple and accurate measure of the functional status of platelets, in patients hospitalized with diagnosis of acute coronary syndromes (ACS). Materials and methods: A total of 216 consecutive patients (156 male, 60 female) hospitalized with the diagnosis of non-ST segment elevation (NSTE) ACS within the first 24 h of their chest pain were enrolled. One hundred and twenty patients, matched according to sex and age, with stable coronary heart disease (CHD) (85 male, 35 female) were enrolled as a control group. Patients were classified into two group: those with unstable angina (USAP, n = 105) and those with non-ST segment elevation myocardial infarction (NSTEMI, n = 111). Results: MPVs were 10.4 ± 0.6 fL, 10 ± 0.7 fL, 8.9 ± 0.7 fL consecutively for NSTEMI, USAP and stable CHD with significant differences. Patients with ischemic attacks in the first day of hospitalization accompanied by >0.05 mV ST segment shift had significantly higher MPV compared to those without such attacks (P = 0.001). Multivariable logistic regression analysis yielded that MPV (P = 0.016), platelet count (P < 0.001), and the presence of >0.05 mV ST segment depression at admission (P = 0.002) were independent predictors of development of NSTEMI in patients presenting with NSTE ACS. Conclusion: In patients presenting with NSTE ACS, higher MPV, though there are overlaps among subgroups, indicates not only more risk of having NSTEMI but also ischemic complications.