Prevention of perioperative venous thromboembolism: 2024 guidelines from the French Working Group on Perioperative Haemostasis (GIHP) developed in collaboration with the French Society of Anaesthesia and Intensive Care Medicine (SFAR), the French Society of Thrombosis and Haemostasis (SFTH) and the French Society of Vascular Medicine (SFMV) and endorsed by the French Society of Digestive Surgery (SFCD), the French Society of Pharmacology and Therapeutics (SFPT) and INNOVTE (Investigation Network On Venous ThromboEmbolism) network.

Background: Any surgical procedure carries a risk for venous thromboembolism (VTE), albeit variable. Improvements in medical and surgical practices and the shortening of care pathways due to the development of day surgery and enhanced recovery after surgery, have reduced the perioperative risk for VTE.

Objective: A collaborative working group of experts in perioperative haemostasis updated in 2024 the recommendations for the Prevention of perioperative venous thromboembolism published in 2011.

Management of Therapeutic-intensity Unfractionated Heparin: A Narrative Review on Critical Points.

Nowadays, unfractionated heparin (UFH) use is limited to selected patient groups at high risk of both bleeding and thrombosis (patients in cardiac surgery, in intensive care unit, and patients with severe renal impairment), rendering its management extremely challenging, with many unresolved questions despite decades of use. In this narrative review, we revisit the fundamental concepts of therapeutic anticoagulation with UFH and address five key points, summarizing controversies underlying the use of UFH and discussing the few recent advances in the field: (1) laboratory tests for UFH monitoring have significant limitations; (2) therapeutic ranges are not well grounded; (3) the actual influence of antithrombin levels on UFH's anticoagulant activity is not well established; (4) the concept of UFH resistance lacks supporting data; (5) scarce data are available on UFH use beyond acute venous thromboembolism. We therefore identified key issues to be appropriately addressed in future clinical research: (1) while anti-Xa assays are often considered as the preferred option, we call for a vigorous action to improve understanding of the differences between types of anti-Xa assays and to solve the issue of the usefulness of added dextran; (2) therapeutic ranges for UFH, which were defined decades ago using reagents no longer available, have not been properly validated and need to be confirmed or reestablished; (3) UFH dose adjustment nomograms require full validation.

Impact of thrombophilia on venous thromboembolism management.

Hypercoagulable states, also called thrombophilia, can either be congenital or acquired. Congenital thrombophilia, associated mainly with venous thrombosis, is either secondary to coagulation-inhibitor deficiencies, i.e.

Sensitivity and specificity of strategies to identify patients with hemostasis abnormalities leading to an increased risk of bleeding before scheduled intervention: the Hemorisk study.

Background: Preoperative identification of patients with hemostasis abnormalities leading to an increased bleeding risk is based on routine hemostasis tests: prothrombin time (PT), activated partial thromboplastin time (APTT), and platelet count. Because of their low predictive performance, guidelines recommend replacing them with structured bleeding risk questionnaires, but none is validated in this population.

Objectives: To assess the diagnostic accuracy of 3 strategies, performed at the preanesthesia visit before scheduled interventions, and to identify patients with hemostasis abnormalities leading to an increased bleeding risk METHODS: A multicenter study was performed in 7 French academic hospitals, involving patients scheduled for surgical intervention, without antiplatelet/anticoagulant treatment.

[Interference of oral anti-Xa anticoagulants during monitoring of unfractionated heparin treatments: practical and future attitudes].

Contrary to direct oral anticoagulants (DOAC), unfractionated heparin (UFH) requires daily monitoring when administered at therapeutic dose. At present, UFH monitoring is preferably carried out by measuring plasma anti-Xa activity, however, in patients previously treated with an anti-Xa DOAC and switched to UFH, there is a high risk of DOAC interfering with the measurement of UFH anti-Xa activity. Residual anti-Xa DOAC in the sample can lead to an overestimation of the anticoagulant activity attributed to heparin and thus to incorrect anticoagulation.

The use of 1E12, a monoclonal anti-platelet factor 4 antibody, to improve the diagnosis of vaccine-induced immune thrombotic thrombocytopenia.

Background: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a complication of adenoviral-based vaccine against SARS-CoV-2 due to prothrombotic immunoglobulin (Ig) G antibodies to platelet factor 4 (PF4) and may be difficult to distinguish from heparin-induced thrombocytopenia (HIT) in patients treated with heparin.

Objectives: We assessed the usefulness of competitive anti-PF4 enzyme immunoassays (EIAs) in this context.

Methods: The ability of F(ab')2 fragments of 1E12, 1C12, and 2E1, 3 monoclonal anti-PF4 antibodies, to inhibit the binding of human VITT or HIT antibodies to PF4 was evaluated using EIAs.

Antithrombin Levels and Heparin Responsiveness during Venoarterial Extracorporeal Membrane Oxygenation: A Prospective Single-center Cohort Study.

Background: Unfractionated heparin, administered during venoarterial extracorporeal membrane oxygenation to prevent thromboembolic events, largely depends on plasma antithrombin for its antithrombotic effects. Decreased heparin responsiveness seems frequent on extracorporeal membrane oxygenation; however, its association with acquired antithrombin deficiency is poorly understood. The objective of this study was to describe longitudinal changes in plasma antithrombin levels during extracorporeal membrane oxygenation support and evaluate the association between antithrombin levels and heparin responsiveness.

Reassessment of dextran sulfate in anti-Xa assay for unfractionated heparin laboratory monitoring.

Background: Anti-Xa assays are used for unfractionated heparin (UFH) monitoring. Dextran sulfate (DS) is used in some assays to overcome the artifactual preanalytical release of platelet factor 4. However, the practical implications of this test modification have not been studied extensively.

Factors Influencing Unfractionated Heparin Pharmacokinetics and Pharmacodynamics During a Cardiopulmonary Bypass.

Background: Unfractionated heparin (UFH) is commonly used during cardiac surgery with a cardiopulmonary bypass to prevent blood clotting. However, empirical administration of UFH leads to variable responses. Pharmacokinetic and pharmacodynamic modeling can be used to optimize UFH dosing and perform real-time individualization.

Comparisons between diluted thrombin time, ecarin chromogenic assays, and UPLC-MS for plasma level dabigatran quantification: Results from DRIVING study.

Introduction: The knowledge of dabigatran levels is helpful for decision-making in specific situations such as urgent surgery or when the question of reversal arises (uncontrolled bleeding, eligibility for thrombolysis). However, a limited number of observational studies are available regarding comparisons between quantification methods. The objective of the study was to compare dabigatran plasma levels using three assays including the reference method (high-performance liquid chromatography coupled with mass spectrometry), focusing on the agreement around the 30-50 ng/mL clinically relevant thresholds.

A performance evaluation of sthemO 301 coagulation analyzer and associated reagents.

Aim: The study objective was to evaluate the performance of sthemO 301 system and to compare it with the analyzer used in our university hospital laboratory (STA R Max® 2), for a selection of hemostasis parameters.

Methods: Method comparison (according to CLSI EP09-A3), carryover (according to CLSI H57-A), APTT sensitivity to heparin (according to CLSI H47-A2), HIL level assessment, and productivity were performed using leftover samples from our laboratory (n > 1000). Commercial quality control materials were used to evaluate precision (according to CLSI EP15-A3) and accuracy.

Factors Influencing Anti-Xa Assays: A Multicenter Prospective Study in Critically Ill and Noncritically Ill Patients Receiving Unfractionated Heparin.

Background:  The presence of dextran sulfate (DS) in reagents and the type of blood collection tube (citrate/citrated-theophylline-adenosine-dipyridamole [CTAD]) can lead to discrepancies between unfractionated heparin (UFH) anti-Xa levels.

Objectives:  To evaluate the extent of the effect (1) of different reagents containing or not containing DS and (2) of the blood collection tubes, on UFH anti-Xa levels, in various clinical situations (NCT04700670).

Methods:  We prospectively included patients from eight centers: group (G)1, cardiopulmonary bypass (CPB) after heparin neutralization ( = 39); G2, cardiothoracic intensive care unit (ICU) after CPB ( = 35); G3, medical ICU ( = 53); G4, other medical inpatients ( = 38).

Management of Gastrointestinal Bleeding and Resumption of Oral Anticoagulant Therapy in Patients with Atrial Fibrillation: A Multidisciplinary Discussion.

Direct oral anticoagulants (DOACs) are recommended for the prevention of thromboembolism in patients with atrial fibrillation (AF), and are now preferred over vitamin K antagonists due to their beneficial efficacy and safety profile. However, all oral anticoagulants carry a risk of gastrointestinal (GI) bleeding. Although the risk is well documented and acute bleeding well codified, there is limited high-quality evidence and no guidelines to guide physicians on the optimal management of anticoagulation after a GI bleeding event.

Impact of age on metabolism of clopidogrel: a potential explanation for high on-treatment platelet reactivity in the elderly?

Background: High on-treatment platelet reactivity has been reported in 30% of patients on clopidogrel and 50% in elderly patients; however, little is known about the mechanisms of this biological resistance. One hypothesis is an age-related impaired hepatic metabolism of the prodrug clopidogrel, leading to a lower formation of its active metabolite (clopidogrel-AM).

Objectives: To compare the levels of clopidogrel-AM formed using "old" and "young" human liver microsomes (HLMs) and their consequences on platelet functions.

Transferability of Published Population Pharmacokinetic Models for Apixaban and Rivaroxaban to Subjects with Obesity Treated for Venous Thromboembolism: A Systematic Review and External Evaluations.

Apixaban and rivaroxaban have first-line use for many patients needing anticoagulation for venous thromboembolism (VTE). The pharmacokinetics of these drugs in non-obese subjects have been extensively studied, and, while changes in pharmacokinetics have been documented in obese patients, data remain scarce for these anticoagulants. The aim of this study was to perform an external validation of published population pharmacokinetic (PPK) models of apixaban and rivaroxaban in a cohort of obese patients with VTE.

Assessment of DOAC in GEriatrics (Adage Study): Rivaroxaban/Apixaban Concentrations and Thrombin Generation Profiles in NVAF Very Elderly Patients.

Background:  Although a growing number of very elderly patients with atrial fibrillation (AF), multiple conditions, and polypharmacy receive direct oral anticoagulants (DOACs), few studies specifically investigated both apixaban/rivaroxaban pharmacokinetics and pharmacodynamics in such patients.

Aims:  To investigate: (1) DOAC concentration-time profiles; (2) thrombin generation (TG); and (3) clinical outcomes 6 months after inclusion in very elderly AF in-patients receiving rivaroxaban or apixaban.

Methods:  Adage-NCT02464488 was an academic prospective exploratory multicenter study, enrolling AF in-patients aged ≥80 years, receiving DOAC for at least 4 days.

Bleeding and thrombotic events in patients with severe COVID-19 supported with extracorporeal membrane oxygenation: a nationwide cohort study.

Purpose: To describe bleeding and thrombotic events and their risk factors in patients receiving extracorporeal membrane oxygenation (ECMO) for severe coronavirus disease 2019 (COVID-19) and to evaluate their impact on in-hospital mortality.

Methods: The ECMOSARS registry included COVID-19 patients supported by ECMO in France. We analyzed all patients included up to March 31, 2022 without missing data regarding bleeding and thrombotic events.