Hypercoagulation detected by Rotational Thromboelastometry predicts mortality in COVID-19: A risk model based on a prospective observational study.

ABSTRACT Background: Severe disease due to COVID-19 has been shown to be associated with hypercoagulation. The aim of this study was to assess Rotational Thromboelastometry (ROTEM®) as a marker of coagulopathy in hospitalized COVID-19 patients. Methods: This was a prospective, observational study where patients hospitalized due to a COVID-19 infection were eligible for inclusion. Conventional coagulation tests and ROTEM were taken after hospital admission, and patients were followed for 30 days. A prediction model including variables ROTEM EXTEM-MCF (Maximum Clot Firmness), which in previous data has been suggested a suitable marker of hypercoagulation, age and respiratory frequency was developed using logistic regression to evaluate the probability of death. Results: Out of the 141 patients included, 18 (13%) died within 30 days. In the final prediction model, the risk of death within 30 days for a patient hospitalized due to COVID-19 was increased with increased EXTEM-MCF, age and respiratory frequency. Longitudinal ROTEM data in the severely ill subpopulation showed enhanced hypercoagulation. In an in vitro analysis, no heparin effect on EXTEM-CT (Coagulation Time) was observed, supporting a SARS-CoV-2 effect on prolonged initiation of coagulation. Conclusions: Here we show that hypercoagulation measured with ROTEM predicts 30-days mortality in COVID-19. Longitudinal ROTEM data strengthen the hypothesis of hypercoagulation as a driver of severe disease in COVID-19. Thus, ROTEM may be a useful tool to assess disease severity in COVID-19 and could potentially guide anticoagulation therapy.

Temporary rise in blood thrombogenicity in patients with acute myocardial infarction

Objective: Although blood thrombogenicity seems to be one of the determinant factors for the development of acute myocardial infarction (MI), it has not been dealt with in-depth. This study aimed to investigate blood thrombogenicity and its change in acute MI patients. Methods and Results: We designed a prospective, observational study that included 51 acute MI patients and 83 stable coronary artery disease (CAD) patients who underwent cardiac catheterization, comparing thrombogenicity of whole blood between: (1) acute MI patients and stable CAD patients; and (2) acute and chronic phase in MI patients. Blood thrombogenicity was evaluated by the Total Thrombus-Formation Analysis System (T-TAS) using the area under the flow pressure curve (AUC30) for the AR-chip. Acute MI patients had significantly higher AUC30 than stable CAD patients (median [interquartile range], 1771 [1585 - 1884] vs. 1677 [1527 - 1756], p = 0.010). Multivariate regression analysis identified acute MI with initial TIMI flow grade 0/1 as an independent determinant of high AUC30 (β = 0.211, p = 0.013). In acute MI patients, AUC30 decreased significantly from acute to chronic phase (1859 [1550 - 2008] to 1521 [1328 - 1745], p=0.001). Conclusion: Blood thrombogenicity was significantly higher in acute MI patients than in stable CAD patients. Acute MI with initial TIMI flow grade 0/1 was significantly associated with high blood thrombogenicity by multivariate analysis. In acute MI patients, blood thrombogenicity was temporarily higher in acute phase than in chronic phase.

Daily monitoring of D-dimer allows outcomes prediction in COVID-19

No Abstract

Global Thrombosis Test: Occlusion is attributable to shear-induced platelet thrombus formation.

Herein, we set out a rebuttal to the publication by Claveria and co-workers published in TH Open this month entitled “Global Thrombosis Test: Occlusion by Coagulation or SIPA?” We strongly believe that the conclusions of their paper, suggesting that occlusion (OT) in the Global Thrombosis Test (GTT) is due to coagulation, rather than shear-induced platelet thrombus formation, is incorrect and the evidence and arguments they present are fundamentally flawed, with major errors both in the experimental approach and in the interpretations of the results. The evidence which they demonstrate, shows that occlusion in the GTT is, in fact, caused by high shear induced platelet thrombus formations. We set out herein the evidence for that, based on histology of the thrombus from the GTT in earlier work using electron microscopy showing large platelet aggregates, the very brief timescale of OT in the GTT compared to coagulation time and the sensitivity of the OT in the GTT to the effects of heparin, t-PA and P2Y12 inhibitors. In addition, we revisit the known pathomechanism of high shear-mediated platelet aggregation to underpin our rationale and show that the modifications to the instrument proposed by Claveria and co-authors would render the technique unphysiological. We highlight several methodological concerns and apparent misinterpreted of the data obtained. We present evidence predominantly from the authors’ own data, together with our earlier published data and evidence from the literature, showing that occlusion in the GTT occurs do to shear-induced platelet aggregation.

Carotid Artery Stenosis and ischemic Strokes in Patients with Giant Cell Arteritis A characteristic Pattern - Literature Review and Case Report

Purpose: Ischemic stroke is a relatively rare complication of giant cell arteritis often accompanied by vessel stenosis. Our purpose was to compare the location of internal carotid artery stenosis in GCA patients by performing a literature review suggesting a specific and characteristic pattern. Methods: We performed a Pubmed research including all articles and cited articles reporting cases and case series about giant cell arteritis patients with internal carotid artery stenosis and ischemic strokes. Results: In this case series 39 cases were included. We found a clear tendency of giant cell arteritis related stenosis to be in the intracranial segments (35/39 (89,7 %)). Only in 8/39 (20,5 %) patients there was further involvement of extracranial segments. Many cases (27/39 (69,2 %)) showed a bilateral involvement. Discussion: This literature review reveals a specific pattern of internal carotid artery involvement in patients with giant cell arteritis and ischemic strokes. To our knowledge this pattern has not been reported as a sign strongly pointing towards giant cell arteritis before. We have not found case reports mentioning other common types of vasculitis reporting this involvement pattern. Conclusion: Internal carotid artery stenosis and ischemic stroke is a rare complication in patients with giant cell arteritis. Considering the characteristic features of bilateral distal internal carotid artery stenosis giant cell arteritis should be suspected which potentially leads to an early diagnosis and immunotherapy.

Analysis of 180 genetic variants in a new interactive FX variant database reveals novel insights into FX deficiency

Coagulation Factor X (FX), often termed Stuart-Prower Factor, is a plasma glycoprotein composed of the γ-carboxyglutamic acid (Gla) domain, two epidermal growth factor domains (EGF-1, EGF-2) and the serine protease (SP) domain. FX plays a pivotal role in the coagulation cascade, activating thrombin to promote platelet plug formation and prevent excess blood loss. Genetic variants in FX disrupt coagulation and lead to FX or Stuart-Prower Factor deficiency. To better understand the relationship between FX deficiency and disease severity, an interactive FX variant database has been set up at https://www.factorx-db.org, based on earlier websites for the Factor XI and IX coagulation proteins. To date (April 2021), we report 427 case reports on FX deficiency corresponding to 180 distinct F10 genetic variants. Of these, 149 are point variants (of which 128 are missense), 22 are deletions, three are insertions and six are polymorphisms. FX variants are phenotypically classified as being Type I or Type II. Type I variants involve the simultaneous reduction of FX coagulant activity (FX:C) and FX antigen levels (FX:Ag), whereas Type II variants involve a reduction in FX:C with normal FX:Ag plasma levels. Both types of variants were distributed throughout the FXa protein structure. Analyses based on residue surface accessibilities showed the most damaging variants to occur at residues with low accessibilities. The interactive FX web database provides a novel easy-to-use resource for clinicians and scientists to improve the understanding of FX deficiency. Guidelines are provided for clinicians who wish to use the database for diagnostic purposes.

Measurement of Anticoagulation in Patients on Dabigatran, Rivaroxaban and Apixaban Therapy by Novel Automated Thrombelastography

Background: Direct-acting oral anticoagulants (DOACs) do not require monitoring. Measurement of DOAC effect would be useful in the event of bleeding, trauma, and thromboembolism while on anticoagulation. We evaluated the effectiveness of the investigational DOAC assays on the TEG®6s Hemostasis Analyzer to assess the anticoagulant effect of DOACs in patients treated for atrial fibrillation or DVT. Methods: Patients on treatment for a minimum of 7 days with standard doses of dabigatran, rivaroxaban and apixaban were included. DOAC plasma concentrations and TEG®6s R-time were measured and correlated. The sensitivity, specificity and negative predictive value (NPV) of R-time to detect DOAC concentrations of ≥ 30, ≥ 50 and ≥ 100 ng/mL were calculated. Results: 189 Subjects were included, (n=50) on apixaban, (n= 62) on rivaroxaban, (n=53) on dabigatran and (n=24) on no DOAC were studied. Using the direct thrombin inhibitor (DTI) channel, R-time demonstrated strong linear correlation with dabigatran levels (r = 0.93, p < 0.0001). Using the anti-factor Xa (AFXa) channel, R-time demonstrated strong non-linear correlation with rivaroxaban and apixaban levels (rs = 0.92 and 0.84 respectively, p < 0.0001 for both). R-time revealed strong sensitivity and NPV in detecting low DOAC levels for the predefined concentrations. Conclusion: R-time measured by TEG®6s DOAC Specific cartridge has a strong correlation with concentrations of the most commonly used DOACs, with high sensitivity and NPV for detecting lower drug levels that are considered clinically relevant for patients in need of antidote, or prior to urgent surgery. Further studies to determine the relation of R-time to clinical outcomes are warranted.

Analysis of 272 genetic variants in the upgraded interactive FXI web database reveals new insights on FXI deficiency

Coagulation Factor XI (FXI) is a plasma glycoprotein composed of four apple (Ap) domains and a serine protease (SP) domain. FXI circulates as a dimer and activates Factor IX (FIX), promoting thrombin production and preventing excess blood loss. Genetic variants that degrade FXI structure and function often lead to bleeding diatheses, commonly termed FXI deficiency. The first interactive FXI variant database underwent initial development in 2003 at https://www.factorxi.org. Here, based on a much improved FXI crystal structure, the upgraded FXI database contains information regarding 272 FXI variants (including 154 missense variants) found in 657 patients, this being a significant increase from the 183 variants identified in the 2009 update. Type I variants involve the simultaneous reduction of FXI coagulant activity (FXI:C) and FXI antigen levels (FXI:Ag), whereas Type II variants result in decreased FXI:C yet normal FXI:Ag. The database updates now highlight the predominance of Type I variants in FXI. Analysis in terms of a consensus Ap domain revealed the near-uniform distribution of 81 missense variants across the Ap domains. A further 66 missense variants were identified in the SP domain, showing that all regions of the FXI protein were important for function. The variants clarified the critical importance of changes in surface solvent accessibility, as well as those of cysteine residues and the dimer interface. Guidelines are provided below for clinicians who wish to use the database for diagnostic purposes. In conclusion, the updated database provides an easy-to-use web resource on FXI deficiency for clinicians.

Combined antiplatelet therapy reduces the pro-inflammatory properties of activated platelets

The cause of atherothrombosis is rupture or erosion of atherosclerotic lesions, leading to an increased risk on myocardial infarction or stroke. Here, platelet activation plays a major role, leading to the release of bioactive molecules, e.g. chemokines and coagulation factors, and to platelet clot formation. Several antiplatelet therapies have been developed for secondary prevention of cardiovascular events, in which anticoagulant drugs are often combined. Besides playing a role in haemostasis, platelets are also involved in inflammation. However, it is unclear whether current antiplatelet therapies also affect platelet immune functions. In this study, the possible anti-inflammatory effects of antiplatelet medications on chemokine release were investigated using ELISA and on the chemotaxis of THP-1 cells towards platelet releasates. The cause of atherothrombosis is rupture or erosion of atherosclerotic lesions, leading to an increased risk on myocardial infarction or stroke. Here, platelet activation plays a major role, leading to the release of bioactive molecules, e.g. chemokines and coagulation factors, and to platelet clot formation. Several antiplatelet therapies have been developed for secondary prevention of cardiovascular events, in which anticoagulant drugs are often combined. Besides playing a role in haemostasis, platelets are also involved in inflammation. However, it is unclear whether current antiplatelet therapies also affect platelet immune functions. In this study, the possible anti-inflammatory effects of antiplatelet medications on chemokine release were investigated using ELISA and on the chemotaxis of THP-1 cells towards platelet releasates. We found that antiplatelet medication acetylsalicylic acid (ASA) led to reduced chemokine (C-C motif) ligand 5 (CCL5) and chemokine (C-X-C motif) ligand 4 (CXCL4) release from platelets, while leukocyte chemotaxis was not affected. Depending on the agonist, αIIbβ3- and P2Y12-inhibitors also affected CCL5 or CXCL4 release. The combination of ASA with a P2Y12 inhibitor or a phosphodiesterase inhibitor did not lead to an additive reduction on CCL5 or CXCL4 release. Interestingly, these combinations did reduce leukocyte chemotaxis. This study provides evidence that combined therapy of ASA and a P2Y12 or PDE3 inhibitor can decrease the inflammatory leukocyte recruiting potential of the releasate of activated platelets.

Design and Baseline Data for a Prospective Observational Study of Rivaroxaban in Patients with Venous Thromboembolism in Japan (XASSENT)

Background The efficacy and safety of rivaroxaban have been demonstrated in phase 3 trials of patients with venous thromboembolism (VTE; pulmonary embolism [PE] and deep vein thrombosis [DVT]). Data regarding rivaroxaban treatment of VTE in routine Japanese clinical practice remain limited. Objectives XASSENT will evaluate rivaroxaban treatment of VTE in real-world Japanese clinical practice. We report the study design and baseline patient characteristics. Methods XASSENT (NCT02558465) is a an open-label, prospective observational, post-marketing surveillance cohort study in patients receiving rivaroxaban treatment for VTE. Enrolment took place between November 2015 and March 2018. XASSENT will follow patients for up to 2 years. Primary outcome variables: major bleeding and symptomatic recurrent VTE. Statistical analyses are exploratory and descriptive. Results Baseline patient characteristics at June 2020 (n=2,299) are presented (58.2% female; mean age 66.7 years; mean weight 60.9kg). The population encompasses patients with wide-ranging characteristics including older age, low weight, and renal dysfunction. Most participants (67.6%) had a history of VTE risk factors at baseline. Half of the population (50.4%) had DVT only; 41.4% had DVT with PE; 8.2% had PE only. Overall, 68.4% were inpatients and 77.1% had symptomatic VTE. Rivaroxaban was prescribed for initial treatment in 84.6% of patients and maintenance treatment in 15.4%. Most were prescribed the approved dose of rivaroxaban for initial (30mg daily; 84.4%) or maintenance (15mg daily; 81.9%) treatment of VTE in Japan. The most common reason for selecting non-recommended dose was ‘elderly’. Conclusions Results from XASSENT will complement phase 3 trial data and inform clinical practice.