Relationship between plasma tissue Factor Pathway Inhibitor (TFPI) levels, thrombin generation and clinical risk of bleeding in patients with severe haemophilia A or B.

INTRODUCTION: Bleeding severity in severe haemophilic patients, with low thrombin generation (TG) capacity, can vary widely between patients, possibly reflecting differences in tissue factor pathway inhibitor (TFPI) level. AIM: To compare free TFPI (fTFPI) levels in patients with severe haemophilia A (sHA) and severe haemophilia B (sHB) and to investigate in these patients as a whole the relationships between bleeding and TG potential, between TG potential and fTFPI level and between fTFPI level and bleeding tendency. METHODS: Data on bleeding episodes retrospectively recorded during follow-up visits over 5-10 years were collected and used to calculate the annualised joint bleeding rate (AJBR). fTFPI levels and basal TG parameters were determined in platelet-poor plasma (PPP) and platelet-rich plasma (PRP) using calibrated automated tomography (CAT). RESULTS: Mean fTFPI levels did not differ significantly between sHA (n = 34) and sHB (n = 19) patients. Mean values of endogenous thrombin potential (ETP) and thrombin peak (peak) in PPP and PRP were two-fold higher when fTFPI levels < 9.4 versus > 14.3 ng/mL. In patients treated on demand, ETP and peak in PRP were doubled when AJBR was ≤ 4.9 $ \le 4.9$ , AJBR being halved in patients with a low fTFPI level (9.4 ng/mL). In patients on factor prophylaxis, no association was found between TG parameters and either fTFPI level or AJBR. CONCLUSION: In patients treated on demand, bleeding tendency was influenced by fTFPI levels, which in turn affected basal TG potential. In patients on prophylaxis, bleeding tendency is probably determined primarily by the intensity of this treatment.

[Point-of-care testing for D-dimer in the exclusion of venous thromboembolism: a critical analysis]. / Les dispositifs délocalisés de dosage des D-dimères dans l'exclusion de la maladie thromboembolique veineuse : une analyse critique.

Point-of-care testing (POCT) for D-dimer is an alternative to -laboratory testing for the exclusion of venous thromboembolism (VTE). This critical review by the "CEC et biologie délocalisée" working group of the "Société Française de Thrombose et d'Hémostase" (French Society of -Thrombosis and Haemostasis) aims to present the characteristics of six POCT D-dimer assays available in France in 2023. The article highlights the need to define VTE -exclusion thresholds specific to each technique and validated by clinical studies. There is insufficient data to validate the use of cut off suggested by manufacturers, and age-adjusted thresholds. The article discusses the role of laboratories in justifying and prescribing POCT D-dimer, according to objective criteria, such as the availability and turnaround time of classical laboratory tests. They should also encourage rational prescribing, limited to patients with low risk of venous thromboembolism, following an assessment of clinical probability according to national and international guidelines.

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 (n = 39); G2, cardiothoracic intensive care unit (ICU) after CPB (n = 35); G3, medical ICU (n = 53); G4, other medical inpatients (n = 38). Blood was collected into citrated and CTAD tubes. Chromogenic anti-Xa assays were centrally performed, using seven reagent/analyzer combinations including two without DS. The association between anti-Xa levels and covariates was tested using a linear mixed-effects model. RESULTS: We analyzed 4,546 anti-Xa values from 165 patients. Median anti-Xa levels were systematically higher with reagents containing DS, whatever the patient group, with the greatest effect observed in G1 (0.32 vs. 0.05 IU/mL). Anti-Xa levels were slightly higher in CTAD than in citrate samples, irrespective of the assay. The model showed: (1) a significant dextran-patient group interaction (p < 0.0001), the effect of DS on anti-Xa levels varying from 30.9% in G4 to 296% in G1, and (2) a significant effect of CTAD, varying between patient groups (p = 0.0302). CONCLUSION: The variability of anti-Xa levels with a great overestimation of the values, using a reagent containing DS, can lead to different treatment decisions, especially after heparin neutralization by protamine. Clinical consequences of these differences remain to be demonstrated.

Smoking and Activated Clotting Time during coronary angiography and angioplasty: protocol for the ACT-Tobacco trial.

Background: During percutaneous transluminal coronary angioplasty (PTCA), activated clotting time (ACT) measurements are recommended to attest a correct anticoagulation level and, if needed, to administer further unfractionated heparin (UFH) to obtain a therapeutic ACT value. Our clinical routine led us to observe that smokers had lower ACT values after standardized UFH administration during PTCA. Procoagulant status in smokers is well documented. Objectives: To determine whether tobacco negatively affects UFH anticoagulation during PTCA when evaluated by ACT. Methods: The ACT-TOBACCO trial is a single-center, noninterventional, prospective study. The primary end point is the comparison of ACT values after standardized UFH administration between active smokers and nonsmokers (active smoker group vs nonsmoker group) requiring coronary angiography followed by PTCA. The main secondary end points include ACT comparison after the first and second standardized UFH administration according to the patient's smoking status (active, ex-, or nonsmoker) and the clinical presentation of ischemic cardiomyopathy: stable (silent ischemia or stable angina) or unstable (unstable angina or acute coronary syndrome without or with ST-segment elevation). Conclusions: To the best of our knowledge, ACT values during PTCA between smokers and nonsmokers have not previously been compared. As current PTCA procedures increase in complexity and duration, the understanding of procoagulant risk factors such as smoking and the need for reliable anticoagulation monitoring becomes essential to balance hemorrhagic risk against thrombotic risk.

[POCT-management during the first wave of Covid-19 in France. Results of a national survey leaded by the SFBC-POCT Working Group]. / Gestion de la biologie délocalisée lors de la première vague de Covid-19 en France. Résultats de l'enquête nationale menée par le groupe de travail des EBMD de la SFBC.

During the first wave of Covid-19 in France, in spring 2020, healthcare institution's laboratory had to adapt itself quickly to the growing demand for emergency biology, in particular by reorganizing their POCT analyzers: redeployment of analyzers and/or new installations. In order to analyze this management, a subgroup of 15 hospital biologists from the SFBC Working Group "Biochemical markers of Covid-19" sent, in fall 2020, an on-line survey to French hospital laboratories using POCT. Answers analysis (n = 86) shows a territorial disparity related to the severity of the first wave: increased activity essentially in red zones, management of unexpected situations, training of additional nursing staff for 40 % of the laboratories... The survey also showed simplification of aspects related to accreditation those periods of health crisis. An additional survey, carried out in the spring of 2021, showed good overall satisfaction of the healthcare services (n = 139) concerning the services provided by biology in the POCT sector. Because of their great adaptation capacity, the laboratories and their POCT-teams have played a key role in the management of the first wave of Covid-19 in France. However, the success of these organizations requires an essential collaboration between laboratories and healthcare services. The results of this survey are fundamental in the context of the prolongation of the pandemia throughout the world with a POCT sector appearing to be growing.

Running after Activated Clotting Time Values in Patients Receiving Direct Oral Anticoagulants: A Potentially Dangerous Race. Results from a Prospective Study in Atrial Fibrillation Catheter Ablation Procedures.

BACKGROUND: Activated Clotting Time (ACT) guided heparinization is the gold standard for titrating unfractionated heparin (UFH) administration during atrial fibrillation (AF) ablation procedures. The current ACT target (300 s) is based on studies in patients receiving a vitamin K antagonist (VKA). Several studies have shown that in patients receiving Direct Oral Anticoagulants (DOACs), the correlation between ACT values and UFH delivered dose is weak. OBJECTIVE: To assess the relationship between ACT and real heparin anticoagulant effect measured by anti-Xa activity in patients receiving different anticoagulant treatments. METHODS: Patients referred for AF catheter ablation in our centre were prospectively included depending on their anticoagulant type. RESULTS: 113 patients were included, receiving rivaroxaban (n = 30), apixaban (n = 30), dabigatran (n = 30), and VKA (n = 23). To meet target ACT, a higher UFH dose was required in DOAC than VKA patients (14,077.8 IU vs. 9565.2 IU, p < 0.001), leading to a longer time to achieve target ACT (46.5 min vs. 27.3 min, p = 0.001). The correlation of ACT and anti-Xa activity was tighter in the VKA group (Spearman correlation ρ = 0.53), compared to the DOAC group (ρ = 0.19). Despite lower ACT values in the DOAC group, this group demonstrated a higher mean anti-Xa activity compared to the VKA group (1.56 ± 0.39 vs. 1.14 ± 0.36; p = 0.002). CONCLUSION: Use of a conventional ACT threshold at 300 s during AF ablation procedures leads to a significant increase in UFH administration in patients treated with DOACs. This increase corresponds more likely to an overdosing than a real increase in UFH requirement.

Impact of Geographic Region on the COMMANDER-HF Trial.

OBJECTIVES: This study sought to compare patient characteristics, outcomes, and treatment effects among regions in the COMMANDER-HF trial. BACKGROUND: Globalization of cardiovascular trials increases generalizability. However, regional differences may also introduce heterogeneity in results. METHODS: Incidence rates and interactions with treatment were recorded in pre-specified regions: Eastern Europe, Western Europe and South Africa, North America, Asia-Pacific, and Latin America. RESULTS: Most patients (n = 3,224; 64.2%) were from Eastern Europe; 458 (9.1%) were from Western Europe and South Africa; 149 (3.0%) were from North America; 733 (14.6%) were from Asia-Pacific; and 458 (9.1%) were from Latin America. Compared with patients from Eastern Europe, patients from Western Europe and South Africa, North America, and Asia-Pacific were older and more likely to have coronary interventions and cardiac devices. Patients from Eastern Europe had the lowest event rates. For the primary outcome of myocardial infarction (MI), stroke, or all-cause death, event rates (100/year) were 11.6 in Eastern Europe (10.8 to 12.5); 19.5 (16.5 to 23.0) in Western Europe and South Africa; 14.2 (10.5 to 19.2) in North America; 17.7 (15.4 to 20.3) in Asia-Pacific; and 18.6 (15.6 to 22.1) in Latin America. There was a lower incidence of bleeding in Eastern Europe. Blood concentrations of rivaroxaban (Xarelto, Titusville, New Jersey) at 4 weeks were undetectable in 21% patients from Eastern Europe (n = 128) compared to 5% in other regions (n = 42). There was no evidence of treatment-by-region heterogeneity for the primary outcome (interactionp = 0.14), but a favorable effect on the secondary outcome of MI, stroke, or cardiovascular death was observed in Western Europe and South Africa, North America, and Latin America but not in Eastern Europe and Asia-Pacific (interactionp = 0.017). CONCLUSIONS: In the COMMANDER-HF study, patients from Eastern Europe had a lower risk profile and fewer cardiovascular and bleeding events, possibly related to lower treatment adherence. Those differences might have influenced the effect of rivaroxaban therapy. (A Study to Assess the Effectiveness and Safety of Rivaroxaban in Reducing the Risk of Death, Myocardial Infarction or Stroke in Participants With Heart Failure and Coronary Artery Disease Following an Episode of Decompensated Heart Failure [COMMANDER HF]; NCT01877915).

Platelet Counting: Ugly Traps and Good Advice. Proposals from the French-Speaking Cellular Hematology Group (GFHC).

Despite the ongoing development of automated hematology analyzers to optimize complete blood count results, platelet count still suffers from pre-analytical or analytical pitfalls, including EDTA-induced pseudothrombocytopenia. Although most of these interferences are widely known, laboratory practices remain highly heterogeneous. In order to harmonize and standardize cellular hematology practices, the French-speaking Cellular Hematology Group (GFHC) wants to focus on interferences that could affect the platelet count and to detail the verification steps with minimal recommendations, taking into account the different technologies employed nowadays. The conclusions of the GFHC presented here met with a "strong professional agreement" and are explained with their rationale to define the course of actions, in case thrombocytopenia or thrombocytosis is detected. They are proposed as minimum recommendations to be used by each specialist in laboratory medicine who remains free to use more restrictive guidelines based on the patient's condition.

Type of plasma preparation used for plasma exchange and clinical outcome of adult patients with acquired idiopathic thrombotic thrombocytopenic purpura: a French retrospective multicenter cohort study.

BACKGROUND: Plasma exchange (PE) is the first-line therapy of acquired thrombotic thrombocytopenic purpura (TTP). Several plasma preparations have been available; their equivalence in terms of outcome remains uncertain. STUDY DESIGN AND METHODS: We performed a retrospective analysis of the cases prospectively reported from 2005 to 2010 to the national registry established by the thrombotic microangiopathies French reference center. We analyzed 108 initial episodes of acquired idiopathic TTP in adults treated with PE, 81 with solvent/detergent (S/D) plasma, and 27 with quarantine fresh-frozen plasma (qFFP). The primary endpoint was the time to platelet (PLT) count recovery. RESULTS: Time to PLT count recovery was not significantly different with S/D plasma versus qFFP (median, 15 days vs. 19 days, respectively; p = 0.126). Complete remission rates, exacerbations, and survival were comparable. By multivariate competitive risk (Fine-Gray) analysis, the only significant association with a shorter time to PLT count recovery was the absence of additional treatment (hazard ratio, 2.06; 95% confidence interval [CI], 1.39-3.05; p < 0.001). There was a significant interaction between type of plasma and age, and for patients less than 40 years old, the use of S/D plasma was associated with a shorter time to PLT count recovery versus qFFP (median, 13 [95% CI, 9-16] days vs. 20 [95% CI, 16-64] days, respectively; p = 0.004). CONCLUSION: The outcomes of acquired TTP treated with S/D plasma or qFFP seem similar and therefore both preparations can be used safely for PE in this indication. The faster response of S/D plasma observed in younger patients warrants confirmation in prospective studies.

[A case of dysfibrinogenemia without hemorrhagic diathesis or thromboembolism linked to a new mutation p.H103N in fibrinogen γ chain]. / Un cas de dysfibrinogénémie sans complication hémorragique ni thrombotique lié à une nouvelle mutation p.H103N de la chaîne γ du fibrinogène.

This work describes a dysfibrinogenemia linked to a new mutation in the gene coding for fibrinogen γ chain. Dysfibrinogenemia was fortuitously discovered in a 9-year old boy consulting for symptoms suggesting meningitis. DNA was extracted from blood, the fibrinogen genes coding for Aα, Bß and γ chains were sequenced, and compared with consensus sequences. Apart from the patient, dysfibrinogenemia and the mutation p.H103N in the γ chain of fibrinogen with heterozygous status were found in his mother, without any symptom. This mutation is unknown in fibrinogen variant databases and seems to affect mostly fibrin polymerisation. The reporting of this new p.H103N mutation in the γ chain has a great interest for improving the knowledge of the fibrinogen gene and its expression. Even if no haemorrhage was observed in this case, the expression of this mutation impaired the function of the molecule, particularly polymerisation, and could induce bleeding during an important surgery.

Internal carotid thrombus in patients with inflammatory bowel disease: two cases.

Increased ischemic stroke risk is observed in patients with inflammatory bowel disease (IBD). Causes and physiopathological aspects of cerebral infarct, in this specific population, are less often described. There is little information to provide guidelines for the best curative and preventive treatment. We report 2 cases of ischemic strokes due to internal carotid thrombus in patients during active phase of IBD. Ulceration of early atherosclerotic plaques activated by a hypercoagulation state may cause a thrombus. A combined therapy with heparin and corticosteroids was used for both our patients. Lysis of the thrombus was obtained after several days without surgical treatment and shown by ultrasonography. These cases highlight an aetiology of stroke in patients with IBD and use of a synergic treatment to respond to hypercoagulability in link with IBD. Benefits and safety of this therapy should be confirmed with clinical studies.

Platelet-dependent thrombography gives a distinct pattern of in vitro thrombin generation after surgery with cardio-pulmonary bypass: potential implications.

BACKGROUND: Bleeding remains a potentially lethal complication of cardio-pulmonary bypass (CPB) surgery. The purpose of this study was to obtain a better insight into in vitro thrombin generation in the context of CPB. METHODS: We used Calibrated Automated Thrombography to assess blood coagulation of 10 low-risk patients operated for valve replacement with CPB, under 2 experimental conditions, one implicating platelets as platelet dysfunction has been described to occur during CPB. RESULTS: Our main finding was that CPB-induced coagulopathy was differently appreciated depending on the presence or absence of platelets: the decrease in thrombin generation was much less pronounced in their presence (mean endogenous thrombin potential change values before and after CPB were -3.9% in the presence of platelets and -39.6% in their absence). CONCLUSION: Our results show that experimental conditions have a profound effect in the study of in vitro thrombin generation in the context of CPB.

Off-label use of recombinant activated factor VII in intractable haemorrhage after cardiovascular surgery: an observational study of practices in 23 French cardiac centres (2005-7).

OBJECTIVES: The study aimed to describe French off-label use of rFVIIa for intractable bleeding in major cardiovascular surgery. METHODS: Retrospective observational analysis of data from 2005 to October 2007 (no formal guidelines were available) was employed. The collect request form was elaborated by a multidisciplinary committee. RESULTS: Data on 109 patients--37 mechanical cardiac assist devices--were collected, with repeated injection for 24%. Bleeding stopped, decreased or continued in 43%, 37% and 20% of the cases, respectively. For patients treated in the intensive care unit (ICU), hourly bleeding decreased from 365 ± 212 to 115 ± 106 ml h(-1) (p<0.001). The median number of transfused products was 25 (2-90) before and 6 (0-48) after rFVIIa (p<0.001). Most patients had been well compensated with fibrinogen (>1g.l(-1)) and platelets (>50 G.l(-1)) before rFVIIa. The bleeding outcome (cessation, decrease or no change) was associated with the infused dose (81 ± 31, 71 ± 24, 64 ± 23 µg.kg(-1); p = 0.044) and did not differ whether rFVIIa was administered in the operating room (49%) or ICU (51%). Thrombotic events occurred in 13% of patients without assist devices and in 27% of those with them (but without obvious intra-device clotting). The overall 28-day survival rate was 60% and associated with bleeding outcome (p = 0.002). CONCLUSIONS: rFVIIa rescue therapy was followed by control of bleeding in a substantial number of the patients with seemingly acceptable safety; however, thrombotic risk remains a matter of concern. Our observational study suggests that the dose to be tested prospectively is at least 80 µg.kg(-1).

Inter-individual variability of effect of 7 low molecular weight antithrombin-dependent anticoagulants studied in vitro with calibrated automated thrombography.

INTRODUCTION: Low-molecular-weight heparins (LMWHs) and fondaparinux are antithrombin dependent anticoagulant drugs considered to need no laboratory monitoring because of their reputedly predictable anticoagulant effect. However it has been suggested in the literature the existence of an inter-individual variability in response to LMWHs that would be not fully attributable to pharmacokinetics causes. MATERIAL AND METHODS: In order to separate pharmacokinetic from pharmacodynamics effects we studied in 12 platelet-depleted plasmas from normal donors the inhibitory effect on TG determined with the CAT of added UFH, 5 LMWHs and 2 oligosaccharides with anti-Xa activity only. RESULTS: A concentration-dependent inhibition of thrombin generation was found with all molecules tested. The concentration-response relation was very different when the concentrations were expressed in anti-Xa unit but became very similar when expressed in anti-thrombin units regarding LMWHs. Most importantly, we noticed a large inter-individual variability of the inhibitory effects with all molecules tested, UFH and LMWHs alike. The IC40 value varied at least twofold between the highest and the lowest responder. For any given anti-Xa level of any heparin and of pentasaccharide the inhibition of the ETP showed scattering of around 25%. CONCLUSION: In contrast to what is generally assumed the inter-individual variation of the in vitro pharmacodynamics response is equally high for UFH and any LMWH (~25%) and even for the synthetic pentasaccharide. This questions the rationale for standard dosage, the more so as in clinical practice pharmacokinetic variation (e.g. due to body weight) will add to this pharmacodynamic variability.

Recombinant activated factor VII attenuates major arterial bleeding in noncoagulopathic rabbits.

BACKGROUND AND OBJECTIVE: Recombinant activated factor VII (rFVIIa), which is used off-label as an adjuvant therapy for uncontrolled and life-threatening bleeding, might also attenuate intractable bleeding related to macrovascular arterial lesions. Here we evaluated the efficacy of rFVIIa in sealing a large arterial wound in haemostatically competent rabbits. METHODS: Sixty male New Zealand rabbits were randomly divided into vehicle control and 80 and 200 µg kg⁻¹ rFVIIa groups (n = 20 animals each). A standardized wound of the isolated right carotid artery was made in all rabbits with an 18-G catheter. Bleeding, which was limited by mild compression, was assessed every minute. At 5 min, an intravenous bolus of vehicle or human rFVIIa was given and the animals were further observed for 1 h. Efficacy was assessed from the bleeding duration and blood mass lost. Statistical significance was defined as P less than 0.05. All investigators were blinded to the treatment the animals received. RESULTS: The bleeding duration and blood mass lost were significantly reduced in both rFVIIa dosage groups as compared with the vehicle control group. For the vehicle, 80 and 200 µg kg⁻¹ rFVIIa groups, the median bleeding durations were 56 min (range 7-60 min), 15 min (range 5-60 min) and 10 min (range 5-60 min), respectively; and the median blood mass losses were 22.5 g (range 1-58 g), 12 g (range 0-36 g) and 5 g (range 0-31 g), respectively. The prothrombin time was shorter in the rFVIIa groups. Visual inspection of the carotid artery and microscopic analysis of the liver and kidney revealed neither gross thrombi nor entrapped microthrombi in any rabbit. CONCLUSION: Recombinant FVIIa at 80 or 200 µg kg⁻¹ promoted the sealing of a large and slightly compressed arterial wound in rabbits. These results suggest a potential role for the drug in the management of massive bleeds due to an arterial lesion when surgical intervention is not immediately and readily available. Safety should remain a matter of concern.

Levetiracetam-induced platelet dysfunction.

Levetiracetam is an antiepileptic drug widely prescribed. We report here for the first time, an alteration of platelet function attributable to this drug. This effect has never been reported before. The responsibility of levetiracetam seems to be probable: restoration of platelet functionality was observed after withholding this treatment and this effect has been described for a structurally related molecule, piracetam.

Heparin-induced thrombocytopenia and cardiopulmonary bypass: anticoagulation with unfractionated heparin and the GPIIb/IIIa inhibitor tirofiban and successful use of rFVIIa for post-protamine bleeding due to persistent platelet blockade.

Heparin-induced thrombocytopenia was diagnosed in a 50-year-old man on day 5 after cardiac surgery (aorto-coronary bypass and mitral valve replacement). He required redo (para-prosthesis leak) on day 13. The cardiopulmonary bypass (CPB) was performed with unfractionated heparin (UFH) and the platelet glycoprotein (GP) IIb/IIIa inhibitor tirofiban. Post-protamine bleeding likely due to documented persistent platelet blockade by tirofiban was successfully treated with one dose of recombinant activated factor VII (rFVIIa, 60 microg/kg). No thrombotic complications were detected. The management of CPB with UHF and tirofiban is a convenient option and rFVIIa seems appropriate to handle bleeding issues.