Thrombotic microangiopathy, DIC-syndrome and COVID-19: link with pregnancy prothrombotic state.

For last months, humanity has faced a formidable unknown enemy, which is presented as a new coronavirus infection. Despite the fact that the causative agents of new diseases appear at a certain frequency and that the virus SARS-CoV-2 has certain common properties with its predecessors, at the moment we are dealing with a new unknown pathogenesis of the development of severe complications in patients with risk factors. A final understanding of pathological process mechanisms is the goal of the scientific community. Summarizing research data from different countries, it became obvious that in severe cases of viral infection, we are dealing with a combination of the systemic inflammatory response syndrome, disseminated intravascular coagulation and thrombotic microangiopathy (TMA). Thrombotic microangiopathy is represented by a group of different conditions in which thrombocytopenia, hemolytic anemia, and multiple organ failure occur. The article reflects the main types of TMA, pathogenesis and principles of therapy. The main participants in the process are described in detail, including the von Willebrand factor and ADAMTS-13. Based on the knowledge available, as well as new data obtained from patients with COVID-19, we proposed possible models for the implementation of conditions such as sepsis, TMA, and DIC in patients with severe new coronavirus infection. Through a deeper understanding of pathogenesis, it will be possible to develop more effective diagnosis and therapy.

Anticoagulants in frail patients. Seven situations at risk.

In the case of venous thromboembolic disease (VTE), physicians are facing more and more difficulties in managing VTE and their treatment in frail patients. These patients could present several risk situations such as: chronic kidney disease (CKD), underweight or malnourished, falls, cognitive impairment, multi-medicated patients, cancer and pregnancy. Guidelines typically recommend anticoagulation. There are multiple challenges in the safe use of anticoagulation in frail patients, including bleeding risk, monitoring and adherence, and polypharmacy. The objective of this review is to explore these at-risk situations and to suggest adequate anticoagulation therapy, when possible, in each of these complex situations.

Meeting Report EuroG20 Meeting on Cancer-Associated Thrombosis (CAT) Bergamo, Italy 7 April 2016.

The EuroG20 meeting on cancer-associated thrombosis (CAT) convened in Bergamo, Italy on 7 April 2016 to discuss a selection of controversial topics in CAT management. This satellite meeting besides ICTHIC in Bergamo has the objective to propose an European Guidance on CAT in various complex situations where evidence-based guidelines are lacking, driven by eminence-based thoughts of 20 experts and key opinion leaders in thrombosis from EU area and 8 experts from the rest of the world.

Real-Life Peak and Trough Dabigatran Plasma Measurements over Time in Hospitalized Geriatric Patients with Atrial Fibrillation.

BACKGROUND: Few geriatric patients were included in studies on direct oral anticoagulants and data on dabigatran concentration and safety are needed in this population. Our objectives were to evaluate peak and trough dabigatran plasma concentrations over time in a geriatric population and to identify factors associated with dabigatran plasma concentrations and to assess the relationship with bleeding events. METHODS: Peak and trough dabigatran plasma concentration were performed 4,8,15,30,45 days after inception of dabigatran treatment in 68 consecutive patients ≥75 years old hospitalized in a geriatric hospital with atrial fibrillation. Bleeding events were monitored for 1 year. RESULTS: Mean age was 85.8(5.1) years old and 76.5% were women. Overall, 541 dabigatran plasma measurements (270 peak, 271 trough) were performed. Mean dabigatran concentrations of the 5 sequential measurements ranged 106-146ng/mL for peak and 66-84ng/mL for trough. Renal failure was associated with high peak and trough dabigatran concentration. Inter- and intra-individual coefficients of variation were 59.5% and 44.7% for peak and 74.5% and 44.6% for trough. Participants in the lower two tertiles of dabigatran concentration at day 8 (D8) remained below the 90th percentile (243.9ng/ml) on the next measurements. Bleeding events were associated with high trough dabigatran concentrations. Trough dabigatran concentration at D8>243.9ng/mL significantly predicted bleeding. CONCLUSION: In this geriatric population, renal function and low albumin were associated with dabigatran concentrations. Despite large variability, participants in the lower two tertiles of dabigatran concentration at D8 remained below the 90th percentile on the following measurements. D8 dabigatran trough concentration≥243.9ng/mL identified patients at risk of bleeding.

Physicians' decision about long-term thromboprophylaxis in cancer outpatients: CAT AXIS, a case vignette study on clinical practice in France.

PURPOSE: Data on long-term venous thromboembolism prophylaxis in cancer outpatients remain scarce. In the absence of clear and consistent treatment guidelines, our objectives were to describe and better understand clinical practice and to identify factors influencing the use of thromboprophylaxis. METHODS: CAT AXIS was a multicentred cross-sectional study based on the completion of physician-profile questionnaires and the assessment of 10 e-mailed credible clinical scenarios of lung, colon and breast cancers by each of participants using the case vignette-validated method. RESULTS: A total of 224 physicians participated allowing the completion and the analysis of 2085 reviewed case vignettes corresponding to 765, 703 and 617 fictive clinical scenarios on lung, colon and breast cancers, respectively. The overall rate of thromboprophylaxis was 680/2085 (32.6%) among participants with a comparable proportion for the three types of cancer. Low-molecular-weight heparin (LMWH) was the most frequently used, by 92.7, 93.8 and 83.9% of participants for lung, colon and breast cancers, respectively; thromboprophylaxis duration of ≥ 3 months was used by 74.4% of participants. Multivariate analyses revealed that the Eastern Cooperative Oncology Group index, metastatic malignancy, chemotherapy and history of thrombosis were significantly associated with the therapeutic decision unlike Khorana score and anaemia. CONCLUSION: In the absence of clear guidance, the use of thromboprophylaxis remains low and rather empiric even though the selection of LMWH by the majority of participants and treatment duration seems appropriate based on available data to date. Specific guidelines with corresponding awareness are required.

Prevention and treatment of cancer-associated thrombosis in France: A national survey among vascular disease and supportive care specialists.

BACKGROUND/AIM: Long-term use of low-molecular-weight heparins (LMWH) for the treatment of cancer-associated thrombosis (CAT) has been well-established. Conversely, the use of thromboprophylaxis in patients with cancer remains controversial in the absence of homogeneous guidelines. Our aim was to assess the awareness of treatment guidelines and the management of patients with CAT in daily clinical practice. METHODS: A national survey based on an open questionnaire developed by a panel of health professionals including specialists in vascular medicine, oncology, supportive care and pharmacy, was proposed on line to 2104 specialists experts in the management of CAT with the objective to collect at least 400 answers. Clinical practice assessment included the treatment of lung adenocarcinoma-associated thrombosis, the use of thromboprophylaxis and factors influencing the management of patients with CAT. RESULTS: A total of 401 questionnaires were completed by specialists of vascular medicine (68%), oncology (12%) and other (20%). LMWH was the preferred option for over 90% of the participants for the treatment of recent overt proximal pulmonary embolism or deep-vein thrombosis. Up to 70% of the participants considered treatment duration for 6 months and more than 12 months in case of active malignancy. Patient management in the setting of incidental VTE and thromboprophylaxis were heterogeneous in the absence of clear guidance while VTE risk scores would be used by only 14% of participants. CONCLUSION: Patients with CAT are properly managed based on clear and consistent guidelines. Patient care is heterogeneous regarding treatment duration beyond 6 months and thromboprophylaxis while VTE risk scores are misused. Identification of referent health care professionals for CAT management and more clear guidelines are required.

Long-term treatment of cancer-associated thrombosis: the choice of the optimal anticoagulant.

Patients with cancer-associated thrombosis (CAT) carry a higher risk of recurrence, bleeding and mortality as compared with non-cancer patients. The specific profiles of cancer patients, combining frequent co-morbidities, the use of anti-tumoral therapies and the cancer progression itself, represent a major therapeutic challenge for choosing a long-term anticoagulant treatment. This review discusses the practical basis of making a choice between the available drugs for a long-term antithrombotic strategy, linked to their pharmacology, mechanism of action, evidence of clinical benefits, and advantages and limitations in such a complex clinical context. In patients with cancer, low-molecular-weight heparins (LMWHs) are the preferred option for the secondary prevention of venous thromboembolism according to current guidelines, because their efficacy is significantly superior to vitamin K antagonists (VKAs). Even though LMWHs are effective and safe in cancer patients, they require daily subcutaneous injections, which may be problematic for a long-term therapy that may exceed 6 months' duration. Compared with VKAs, non-vitamin-K antagonist oral anticoagulants or direct oral anticoagulants (DOACs) are more target specific and do not require laboratory monitoring, whereas the oral route of administration makes them potentially attractive alternatives to LMWH. In randomized controlled trials in the general population DOACs have been shown to be non-inferior to VKAs in terms of efficacy with a lower rate of clinically relevant or major bleeding. However, given the limited number of cancer patients enrolled in these studies (with poorly defined active cancer), available trials are inconclusive regarding the usefulness of DOACs in the cancer setting. Ongoing head-to-head comparisons vs. LMWH in patients with CAT may allow an informed choice to be made regarding the DOAC option.

OC-03 - Modelisation of the procoagulant properties of cancer cells and their capacity to alter the antithrombotic efficiency of LMWHs and specific inhibitors of factor Xa.

INTRODUCTION: The risk of venous thromboembolism varies according to the histological type of cancer. The failure of antithrombotic treatment is more frequent in cancer patients as compared to non-cancer ones. AIM: We aimed to elucidate the mechanism of activation of blood coagulation induced by cancer, the impact of chemo-resistance phenotype on the capacity of cancer cells to trigger thrombin generation and the alterations of the efficiency of LMWHs and the specific inhibitors of factor Xa (fondaparinux and apixaban) in the presence of cancer cells. MATERIALS AND METHODS: Thrombin generation of human plasma was assessed in the presence of various cancer cell lines. The model of cancer-induced hypercoagulability was coupled to the research for the expression of procoagulant molecules by cancer cells. RESULTS: The pancreatic adenocarcinoma cells BXPC3 and the breast adenocarcinoma cells MCF7 were initially tested. The BXPC3 cells induce significantly higher thrombin generation as compared to the MCF7 cells. In the same line Marchetti et al. showed that malignant hematologic cells (NB4, HEL, and K562) and H69 small cell lung cells express different procoagulant potential on triggering thrombin generation of human plasma. The comparison of the procoagulant activity has been extended to cancer cell lines from various cancers (i.e. colon, ovarian and prostatic cancer) as well as to different cell lines of the same type of cancer. The differences of the cancer cell lines to trigger thrombin generation are mainly due to the expression of TF. The acquisition of chemoresistant phenotype by cancer cells is correlated with increased TF expression and enhancement of theit procoagulant activity. The ability of cancer cells to activate FXII is an alternative pathway of significant importance for some cancer cell lines (i.e. MCF7). Clinically relevant concentrations of LMWH and specific direct and indirect inhibitors of FXa (apixaban and fondaparinux) inhibit thrombin generation induced by cancer cells. The synergy between the anti-Xa and anti-IIa activities of LMWHs rather than the AT-dependent selective inhibition of FXa results in profound inhibition of thrombin generation induced by BXPC3 cells. This experimental model allowed the functional distinction between the two specific FXa inhibitors (apixaban and fondaparinux). CONCLUSIONS: The cancer cell-based model of hypercoagulability is suitable for the identification of the prothrombotic fingerprint of various cancer types. This experimental model allows to perform pharmacological studies for the evaluation of the efficiency of the antithrombotic drugs in cancer-induced hypercoagulability. It is suitable for the study of the impact of anticancer drugs on the procoagulant properties of the cancer cells.

PO-53 - Prospective evaluation of risk assessment models and biological markers of hypercoagulability for the identification of high VTE risk patients with lung adenocarcinoma. The ROADMAP study.

INTRODUCTION: In patients with lung adenocarcinoma (LA), metastasis (MTS), advanced stage and chemotherapy (CTx) are risk factors for thromboembolism (VTE). Routine thromboprophylaxis is not recommended but individualized risk assessment is encouraged. AIM: The selection of the most relevant hypercoagulability biomarkers (HB) for incorporation into the risk assessment models (RAM) for VTE. MATERIALS AND METHODS: Patients with documented LA eligible for CTx at distance of at least 3months from surgery or hospitalization were included. They were either CTx naive (NG) or had received CTx (OTG). Control group (CG) consisted of 30 healthy age & sex-matched individuals. We assessed them for thrombin generation (TG), P-Selectin, heparanase (HPA), procoagulant phospholipids (PPL), factor VIIa, D-Dimers (DDi) and Tissue Factor activity (TFa). RESULTS: Patients showed significantly shortened PPL and higher levels of TFa, DDi and HPA as compared to the CG. FVIIa levels were lower in patients compared to CG. The NG showed significantly shorter lag-time and lower ETP as compared to the OTG. It also showed significantly higher levels of HPA as compared to the OTG.The increase of TG and of HPA, P-Selectin, FVIIa was associated with the stage. Patients with MTS had higher levels of P-Selectin, TFa, DDi, FVIIa, TGT and HPA than those with localized or advanced disease.Patients with VTE had higher baseline levels of DDi, TGT, shorter PPL and lower levels of HPA as compared to those without. Patients who died within 3-months had higher baseline levels of DDi and lower HPA levels as compared to those who were alive. CONCLUSIONS: Increased PPL, TF pathway up regulation, DDi and HPA increase is a universal phenomenon in LA. CTx has an impact on TGT and HPA levels. Baseline values of TGT, PPL, HPA, DDi were related with mortality and thrombosis. The incorporation of HB in VTE-RAMs might improve their predictive value. This concept is being studied on an ongoing trial.

Platelet microparticle generation assay: a valuable test for immune heparin-induced thrombocytopenia diagnosis.

BACKGROUND: Early diagnosis of immune heparin-induced thrombocytopenia (HIT) is essential to improve clinical outcome but remains challenging. The release of platelet microparticles (PMPs) is considered of major pathophysiological significance. OBJECTIVES: The aim of this study was to evaluate performances of PMP generation assay (PMPGA) compared to clinical outcome to diagnose HIT. The second objective was to compare PMPGA with performances of (14)C-serotonin release assay (SRA) on the same series of patients. METHODS: Sera of 53 HIT-suspected patients were retrospectively incubated with citrated-whole blood from healthy donors with 1IU and 500IU/ml of unfractionated heparin (UH). PMPGA was performed using FACSAria® flow cytometer. The clinical diagnosis was established by two blinded independent investigators analysing in a standardized manner the patient's medical records. Performances of PMPGA and SRA (n=53) were evaluated using ROC curve analysis with clinical outcome as reference. RESULTS: In positive HIT patients, PMPs expressing phosphatidylserine are generated with low UH concentration whereas PMP rate decreases significantly in presence of high UH concentration. Using clinical outcome as reference, sensitivity and specificity of PMPGA reached 88.9% (95% CI: 50.7-99.4) and 100.0% (95% CI: 90.0-100.0). Sensitivity and specificity of (14)C-SRA were 88.9% (95% CI: 50.7-99.4) and 95.5% (95% CI: 83.3-99.2). CONCLUSIONS: PMPGA is a rapid and reliable assay for HIT diagnosis. PMPGA showed good correlation with (14)C-SRA performances and predominately with clinical outcome.

Assessment of the performances of AcuStar HIT and the combination with heparin-induced multiple electrode aggregometry: a retrospective study.

BACKGROUND: Early diagnosis of immune heparin-induced thrombocytopenia (HIT) is challenging. HemosIL® AcuStar HIT and heparin-induced multiple electrode aggregometry (HIMEA) were recently proposed as rapid diagnostic methods. OBJECTIVES: We conducted a study to assess performances of AcuStar HIT-IgG (PF4-H) and AcuStar HIT-Ab (PF4-H). The secondary objective was to compare the performances of the combination of Acustar HIT and HIMEA with standardised clinical diagnosis. METHODS: Sera of 104 suspected HIT patients were retrospectively tested with AcuStar HIT. HIMEA was performed on available sera (n=81). The clinical diagnosis was established by analysing in a standardized manner the patient's medical records. These tests were also compared with PF4-Enhanced®, LTA, and SRA in subsets of patients. Thresholds were determined using ROC curve analysis with clinical outcome as reference. RESULTS: Using the recommended thresholds (1.00AU), the negative predictive value (NPV) of HIT-IgG and HIT-Ab were 100.0% (95% CI: 95.9%-100.0% and 95.7%-100.0%). The positive predictive value (PPV) were 64.3% (95% CI: 35.1%-87.2.2%) and 45.0% (95% CI: 23.2%-68.6%), respectively. Using our thresholds (HIT-IgG: 2.89AU, HIT-Ab: 9.41AU), NPV of HIT-IgG and HIT-Ab were 100.0% (95% CI: 96.0%-100.0% and 96.1%-100.0%). PPV were 75.0% (95% CI: 42.7%-94.5%) and 81.8% (95% CI: 48.3%-97.7%), respectively. Of the 79 patients with a medium-high pretest probability score, 67 were negative using HIT-IgG (PF4-H) test at our thresholds. HIMEA was performed on HIT-IgG positive patients. Using this combination, only one patient on 79 was incorrectly diagnosed. CONCLUSION: Acustar HIT showed good performances to exclude the diagnosis of HIT. Combination with HIMEA improves PPV.

Measuring Oral Direct Inhibitors (ODIs) of thrombin and factor Xa: A recommendation from the Subcommittee on Control of Anticoagulation of the Scientific and Standardisation Committee of the International Society on Thrombosis and Haemostasis.

Oral direct inhibitors (ODIs) of thrombin and factor Xa are now approved as anticoagulant drugs. The first two drugs to complete phase III clinical trials for thromboprophylaxis in orthopaedic surgery and treatment of patients with atrial fibrillation or venous thromboembolism were dabigatran and rivaroxaban. These small molecules are given at fixed dose with no requirement for monitoring as pharmacokinetic and pharmacodynamic responses are reliably predicted in patients with adequate renal function who are not taking other interacting drugs. However, there will be clinical circumstances in specific patients when measurement of the anticoagulant effect of an ODI will be required. © 2013 International Society on Thrombosis and Haemostasis.

Prevention and treatment of venous thromboembolism--International Consensus Statement.

The aim of this document is to provide a clear and concise account of the evidence regarding efficacy or harm for various methods available to prevent and manage venous thromboembolism (VTE).

[Acquired hemophilia A in prepartum: case report and literature review]. / Hémophilie A acquise découverte au cours de la grossesse : à propos d'un cas et revue de la littérature.

INTRODUCTION: Acquired hemophilia A (AH) is a rare hemorrhagic disorder, secondary to the occurrence of factor VIII inhibitor. In young patients, this disorder is commonly observed during the post-partum period, and has been rarely documented in the prepartum. We report a new case of a prepartum AH and review literature data. CASE REPORT: An isolated prolongation of the activated partial thromboplastin time (APTT) was fortuitously discovered in a 31-year-old pregnant women, with spontaneous ecchymosis of her lower limbs few days prior to delivery. Coagulation tests revealed decreased factor VIII activity (18%) and the presence of factor VIII inhibitor (1,4 Bethesda unit). In order to eradicate the autoantibody, the patient was first treated with prednisone and then with rituximab. CONCLUSION: Prepartum factor VIII inhibitors need to be precociously recognized to allow prophylactic management of the delivery bleeding.

[Aortic thrombus and splenic infarcts indicating essential thrombocythemia]. / Thrombose de l'aorte et infarctus spléniques révélateurs d'une thrombocytémie essentielle.

Essential thrombocythemia is a myeloproliferative disorder responsible for both hemorrhagic and thrombotic complications mostly venous but also arterial, especially of the microcirculation. We report a 64-year-old female who presented with an aortic thrombus and splenic infarcts indicating essential thrombocythemia. Outcome was favourable with medical treatment combining low-molecular-weight heparin secondarily switched to warfarin, associated with aspirin and hydroxyurea.

[Study of variability in response to aspirin and clopidogrel: clinical and/or biological resistance?]. / Etude de la variabilité de réponse à l'aspirine et au clopidogrel: résistance clinique et/ou biologique?

Millions of people in France are taking long-term treatments with the two main antiplatelet drugs, aspirin and/or clopidogrel. Most of these people are on a secondary preventive regimen after arterial thrombotic events such as myocardial infarction, stroke, or ischemic complications of lower limb arteriopathy. The term resistance is often a source of confusion. When used, its definition should be explicit. It would be probably be wiser to use a term such as "variable response" which is more widely accepted by specialists and researchers. It would be better to use the term variable platelet response since true pharmacological resistance is rare. The distinction may have clinical pertinence in terms of prognosis. An abundant amount of biological and clinical work in the literature has improved our understanding of the topic. Diverse tests for exploring platelet functions can be used to evaluate the biological impact of treatment. They should, in the near future, contribute to the implementation of guidelines or suggestions for optimal therapeutic modalities. Upcoming results of ongoing large-scale prospective studies will be needed before confirming the potential usefulness and clinical pertinence of these tests.