Given the growing number of patients receiving direct oral anticoagulant (DOAC), patients requiring rapid neutralization is also increasing in case of major bleedings or urgent surgery/procedures. ...Idarucizumab is commercialized as a specific antidote to dabigatran while andexanet alfa has gained the Food and Drug Administration and the European Medicines Agency approval as an oral anti-factor Xa inhibitors antidote. Other antidotes or hemostatic agents are still under preclinical or clinical development, the most advanced being ciraparantag. DOAC plasma levels measurement allows to appropriately select patient for antidote administration and may prevent unnecessary prescription of expensive molecules in some acute clinical settings. However, these tests might be inconclusive after some antidote administration, namely andexanet alfa and ciraparantag. The benefit of laboratory monitoring following DOAC reversal remains unclear. Here, we sought to provide an overview of the key studies evaluating the safety and efficacy of DOAC reversal using the most developed/commercialized specific antidotes, to discuss the potential role of the laboratory monitoring in the management of patients receiving DOAC specific antidotes and to highlight the areas that deserve further investigations in order to establish the exact role of laboratory monitoring in the appropriate management of DOAC specific antidotes.
Anticoagulation monitoring and specific reversal agent targets
DOAC: direct oral anticoagulant; dTT: diluted thrombin time; ECA: ecarin chromogenic assay; ECT: ecarin cloting time. Display omitted
•Antidotes for direct oral anticoagulant (DOAC) reversal have been developed.•The role of laboratory monitoring in DOAC reversal using antidotes is unclear.•Dabigatran level prior to idarucizumab could predict reversal outcome.•Oral FXa inhibitor levels cannot be easily measured following andexanet alfa.•DOAC measurement using commercialized assays is not possible after ciraparantag.
Antiphospholipid antibodies (aPL) promote endothelial dysfunction, inflammation and procoagulant state. We investigated the effect of hydroxychloroquine (HCQ) on prothrombotic state and endothelial ...function in mice and in human aortic endothelial cells (HAEC). Human aPL were injected to C57BL/6 mice treated or not with HCQ. Vascular endothelial function and eNOS were assessed in isolated mesenteric arteries. Thrombosis was assessed both in vitro by measuring thrombin generation time (TGT) and tissue factor (TF) expression and in vivo by the measurement of the time to occlusion in carotid and the total thrombosis area in mesenteric arteries. TGT, TF, and VCAM1 expression were evaluated in HAEC. aPL increased VCAM-1 expression and reduced endothelium dependent relaxation to acetylcholine. In parallel, aPL shortened the time to occlusion and extended thrombus area in mice. This was associated with an overexpression of TF and an increased TGT in mice and in HAEC. HCQ reduced clot formation as well as TGT, and improved endothelial-dependent relaxations. Finally, HCQ increased the p-eNOS/eNOS ratio. This study provides new evidence that HCQ improves procoagulant status and vascular function in APS by modulating eNOS, leading to an improvement in the production of NO.
Immature platelets (IP) are the youngest circulating platelets, released from megakaryocytes, and demonstrating increased dimensions, significant RNA content, and enhanced activity. Immature platelet ...research focuses on a differential diagnostic help in patients with thrombocytopenia. The objectives of this study were to compare the variability of IP in citrate and EDTA samples, and to determine stability over time.
Fifty-six patients were included for comparison between EDTA and citrate whole blood sample collection. Among the patients, 28 had thrombocytopenia (platelet count < 150G/L). Platelet measurement impedancemetry and fluorimetry were performed with Sysmex XN-9000. The immature platelet fraction (IPF) and absolute immature platelet count (A-IPC) were determined with a fluorescent method.
The mean value of platelet count with fluorescence was, in EDTA sample, 215 ± 171 and, in citrate sample, 153 ± 118 G/L. No significant difference was observed between IPF between EDTA and citrate (7.74 ± 6.68% vs. 8.45 ± 7.37%, p = 0.69), respectively. With the Bland-Altman analysis, the mean difference in the EDTA sample, between 1 and 24 h, was 8.06 ± 6.96% and 8.73 ± 7.12% for IPF, whereas in the citrate sample, between 1 and 6 h, it was 8.60 ± 7.29% and 7.54 ± 6.97%, for IPF. Comparing 1 h EDTA sample with 6 h citrate sample, the variance ratio was 0.974 (95% CI: 0.864-1.084) in IPF.
We confirmed the potential to conduct IP measurements up to 24 h in the EDTA sample and IPF measurements in the citrate sample for up to 6 h. These results may be useful for the use of IPF, which is a promising parameter whose interest in clinical practice and standardization is not yet well defined.
Background: Oral anti-Xa inhibitors have demonstrated noninferiority to vitamin K antagonists (VKAs) for the prevention of stroke in patients with atrial fibrillation and recurrent venous ...thromboembolism. They are associated with a decrease in major bleeding. In contrast with VKA, no coagulation monitoring is required. However, in clinical practice, determination of drug concentration is sometimes necessary. Objective: The objective of this study was to evaluate a low-molecular-weight heparin (LMWH) calibrated anti-Xa assay for the quantification of rivaroxaban and apixaban plasma concentration in emergency. Methods: The anti-Xa plasma concentration of rivaroxaban and apixaban were measured in emergency in 210 patients using STA anti-Xa liquid assay. For each plasma concentration <150 ng/mL of rivaroxaban or apixaban, an anti-Xa assay calibrated with LMWH was performed. Results: We demonstrated a significant correlation between LMWH anti-Xa activity and rivaroxaban (R2 = 0.947) or apixaban (R2 = 0.959) concentration and a significant correlation between rivaroxaban and apixaban plasma concentration (R2 = 0.972). A LMWH anti-Xa activity <0.50 IU/mL could exclude a plasma concentration of rivaroxaban and apixaban >30 ng/mL and indicate the feasibility of invasive procedure. Conclusion and Relevance: In the absence of a specific test, LMWH-calibrated anti-Xa assay could be used to determine the presence and evaluate the plasma concentration of oral anti-Xa inhibitors. However, these initial findings require confirmation using other chromogenic calibrated oral anti-Xa assays.
•Factor XI deficiency in plasma was not correlated with clinical bleeding phenotype.•With 1 pM of tissue factor, a non-significant decrease of TGA was observed in FXI deficiency bleeders.•During ...pregnancy, a normalization of thrombin generation was observed in FXI deficiency.
Factor XI (FXI) deficiency is characterized by a lack of correlation between FXI plasma levels and the occurrence of hemorrhagic events. The main objective of our study was to determine whether thrombin generation assay (TGA) could be used to assess the hemorrhagic phenotype of patients with FXI deficiency.
All patients had confirmed laboratory measurement of FXI < 50% in two plasma samples. Relevant bleeding history was evaluated by a senior physician. TGA was performed with Calibrated Automated Thrombography, in platelet poor plasma, from patients and healthy controls. The assay was performed with PPP low reagent (1 pM of human tissue factor).
Seventy-six patients with FXI deficiency were included between 2011 and 2020. Among them, eight patients had severe deficiency (FXI < 15%). Mean age was 34 years range: 9–77. Endogenous thrombin potential (ETP) was significantly lower in patients with FXI deficiency and bleeding (573 nM·min 225–1214) or no bleeding (732 nM·min 222–1435), compared to healthy controls (1184 nM·min 933–1518). No difference was observed for ETP and peak between patients with FXI deficiency and bleeding and patients with FXI deficiency and no bleeding. No difference was observed for ETP (923 nM·min 377–1497 vs 1063 nM·min 252–2529), peak (82 nM 28–154 vs 131 nM 20–330) or velocity (13.7 nM/min 3.6–29.6 vs 26.5 nM/min 2.5–90) in women with (n = 4) and without history (n = 17) of post-partum bleeding. No difference of thrombin generation was observed in pregnant women with FXI deficiency (ETP: 1395 nM·min 351–2529; peak: 154 nM 26–330; velocity: 29.6 nM/min 4.1–90.0), compared to healthy controls and a control group of healthy pregnant women.
In conclusion, under our experimental condition, a non-significant decrease of thrombin generation was observed in plasma samples of patients with FXI deficiency and bleeding. Our results suggest an increase of coagulation parameters during pregnancy in women with FXI deficiency. A larger sample size or other experimental conditions are required to evaluate the use of TGA in FXI deficiency.
•Red blood cell disorders are associated with hypercoagulability state.•Thrombin generation assay evaluates hypercoagulability.•All red blood cell disorders reported hypercoagulability on peak and ...velocity.•Splenectomy is associated with hypercoagulability in hereditary spherocytosis.•Co-inherited α-thalassemia with sickle cell trait decreased hypercoagulability.
Heparin-induced thrombocytopenia (HIT) is a rare, iatrogenic condition, characterized by its potential severity and diagnostic difficulties. The diagnosis is based on a set of arguments allowing the ...calculation of a pre-test score pointing to HIT. There are rapid diagnostic tests for suspected HIT. Among these, the STic Expert® HIT has a good sensitivity to detect HIT. However, it must be performed within 2 hours after sampling. The aim of this study was to evaluate a delayed STic Expert® HIT test at 8 hours and in frozen plasma. Thirty-six patients were prospectively included for HIT testing between April 01, 2018, and July 1, 2022, at the University Rouen Hospital. For any request for HIT testing, an analysis by STic Expert® HIT was performed within 2 hours and 8 hours post-sampling. Any positive result was confirmed by a functional test, platelet aggregation with heparin, release of 14C-serotonin assay (SRA), and immunological assay by a research for anti-platelet factor 4 IgG antibodies. Twenty-three patients had a STic Expert® HIT. Sixteen presented platelet aggregations in the presence of heparin and had a positive anti-PF4 test, 17 had a positive SRA. Six patients had no HIT. For the test performed within 2 hours of collection, the Se = 100%, Sp = 68.42%, PPV = 73.91%, and NPV = 100%. The X2 = 18.21 with p < 0.001. For the test performed at 8 hours post sampling, the Se = 100%, Sp = 68.42%, PPV = 73.91% and NPV = 100%. The X2 = 18.21 with p < 0.001. In conclusion, we have demonstrated that the STic Expert® can be used to perform an HIT diagnostic test 8 hours after sampling and on thawed plasma. However, this study needs to be confirmed on a larger number of samples.
Objective
To assess the role of Toll‐like receptors (TLRs) in antiphospholipid antibody (aPL)–mediated vascular abnormalities in patients with primary arterial antiphospholipid syndrome (APS).
...Methods
Forty‐eight subjects participated in the study. Arterial function and structure and TLR pathway activation were determined in patients with primary arterial APS and matched controls. The pathogenic effects of aPL isolated from patients were assessed in wild‐type (WT) and TLR‐knockout mice.
Results
APS patients had endothelial dysfunction, arterial stiffening, and hypertrophy, as evidenced by decreased brachial artery endothelium‐dependent flow‐mediated dilation (FMD) and increased aortic pulse wave velocity and carotid intima‐media thickness (IMT), as compared with controls. Plasma samples from APS patients revealed decreased nitric oxide (NO) availability and a pro‐oxidative, proinflammatory, and prothrombotic state illustrated by a decrease in nitrite and an increase in lipid peroxidation, tumor necrosis factor α levels, and tissue factor (TF) levels. Furthermore, TLR pathway activation was found in APS patients with increased TLR‐2 and TLR‐4 messenger RNA expression and increased protein levels of the activated TLR transduction protein interleukin‐1 receptor–associated kinase 1 in peripheral blood mononuclear cells. Moreover, agonist‐stimulated cell‐surface expression of TLR‐2 and TLR‐4 in circulating monocytes was higher in APS patients than in controls. These changes were positively associated with IMT and negatively associated with FMD. Finally, aPL injection decreased mesenteric endothelium‐dependent relaxation and increased TF expression in WT mice but not in TLR‐2– or TLR‐4–knockout mice.
Conclusion
This translational study supports the notion that TLR‐2 and TLR‐4 play a role in mediating vascular abnormalities in patients with primary arterial APS. TLRs thus constitute a promising pharmacologic target for preventing cardiovascular complications in APS.
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