Diagnosis and management of congenital thrombophilia in the era of direct oral anticoagulants.

Direct oral anticoagulants (DOAC)s are often preferred to other anticoagulants as they are more practical and do not require routine laboratory monitoring. Less is known about their use in congenital thrombophilia. Efficacy of DOACs in congenital thrombophilia, effect of DOACs and other anticoagulants on diagnostic tests as well as efficacy and safety of anticoagulant use in this population is still a matter of debate. In this review we intended to analyze the potential pitfalls of testing for thrombophilia in patients using DOACs and vitamin K antagonists (VKA)s as well as to suggest strategies to improve diagnostic accuracy in this setting. We also reviewed the literature for evidence regarding the safety and efficacy of DOACs in patients with congenital thrombophilia. Some evidence was found supporting the use of DOACs in low risk thrombophilia, although evidence for their use in high risk thrombophilia is limited to small series and case reports. Our findings support the generation of better evidence to support DOAC use for congenital thrombophilia, especially in the high risk subgroups.

Intravenous thrombolysis for acute ischaemic stroke in patients on direct oral anticoagulants.

BACKGROUND AND PURPOSE: Whereas intravenous thrombolysis (IVT) is allowed for acute ischaemic stroke in patients on vitamin K antagonists with international normalized ratio ≤1.7, there are no similar recommendations for patients on direct oral anticoagulants (DOACs), notably due to the lack of coagulation tests to assess the therapeutic effects. Although the literature is scarce, consisting of small case series and retrospective studies, considering the frequency of this situation the French Vascular Neurology Society and the French Study Group on Haemostasis and Thrombosis have worked on a joint position paper to provide a practical position regarding the emergency management of ischaemic stroke in patients on DOACs. METHOD: Based on a review of the literature, the authors wrote a first text that was submitted to a broad panel of members from the two societies. The text was then amended by the authors to address experts' comments and to reach a consensus. RESULTS: In patients with normal renal function and who stopped the DOAC for at least 48 h, the management should not differ from that in patients without oral anticoagulant. In patients who are still on DOACs, mechanical thrombectomy is encouraged preferentially when applicable in first line. Otherwise, when specific tests are available, values <50 ng/ml indicate that IVT is allowed. In the absence of specific tests, standard tests (thrombin time, prothrombin time and activated partial thromboplastin time) can be used for dabigatran and rivaroxaban, although interpretation of these tests may be less reliable. In some patients on dabigatran, idarucizumab may be used before IVT. CONCLUSIONS: In this expert opinion paper, it is suggested that IVT can be performed in patients selected according to the time elapsed since the drug was last taken, renal function, type of hospital where the patient is admitted and plasma concentration of DOAC.

Postauthorization safety study of Clottafact® , a triply secured fibrinogen concentrate in acquired fibrinogen deficiency: a prospective observational study.

BACKGROUND AND OBJECTIVES: A postauthorization safety study was performed between 2009 and 2012 to describe the use of Clottafact® in acquired fibrinogen deficiency in real-life medical practice in France. MATERIALS AND METHODS: One hundred and fifty patients were planned for 28 days of prospective follow-up after infusion. The analysis of this observational study was descriptive and performed according to the type of treatment (curative or preventive) and the origin of the bleed. RESULTS: One hundred and fifty-six patients (16-87 years) were included in 13 centres and treated in five different medical bleeding situations: postpartum (59), other gynaecological/obstetrical (6), trauma (34), liver (13), cardiovascular (23) and other various bleeding situations (21). The mean follow-up time was 18·9 ± 12·3 days. Two patients presented adverse drug reactions: one a pulmonary embolism and the other a four-site venous thromboembolic episode. All were serious with a dubious causal relationship with the study treatment. Efficacy data were collected as a secondary objective. In 150 patients receiving curative treatment, 117 of 159 infusions (73·6%) were considered as successful by the investigators, 35 as moderate (22%) and seven as no response (4·4%). CONCLUSION: The Clottafact® safety profile observed during the study matched the known profile of fibrinogen during use.

Post-authorization safety study of Clottafact® , a triply secured fibrinogen concentrate in congenital afibrinogenemia. A prospective observational study.

BACKGROUND AND OBJECTIVES: A new fibrinogen concentrate Clottafact® was developed according to European guidelines on plasma-derived products. A post-authorization safety study was set up in 2009 as part of the risk management plan. This was a non-interventional, prospective, non-comparative, multicenter study of the use of fibrinogen concentrate for congenital afibrinogenemia in real-life medical practice in France. MATERIALS AND METHODS: The analysis was descriptive and performed on 3 subgroups: prophylaxis vs. on-demand treatment, age (<6, <12 and ≥12) and severity of the deficiency. RESULTS: Fourteen patients [1-78 years] were included in 7 centres and followed for 1 year. Twenty-one adverse drug reactions (ADRs) classically reported with fibrinogen (pallor, chills, cough, vomiting, headache, urticaria and erythematous rash) were reported in 5 of 14 patients. Two ADRs were serious: an anaphylactic shock and a subclavian venous thrombosis with a favourable outcome without sequelae. In the nine patients under prophylaxis, 365 of 367 infusions were considered as successful (99·5%) and 2 as failures. For the five patients treated on-demand, the efficacy was rated as excellent for 27 of 48 infusions and good for the 21 others. CONCLUSION: This study confirms that the benefit/risk balance for this fibrinogen concentrate is favourable.

ATP-binding cassette transporter 1 (ABCA1) deficiency decreases platelet reactivity and reduces thromboxane A2 production independently of hematopoietic ABCA1.

UNLABELLED: ESSENTIALS: The role of ATP-binding cassette transporter 1 (ABCA1) in platelet functions is poorly characterized. We studied the impact of ABCA1 deficiency on platelet responses in a mouse model and two Tangier patients. ABCA1-deficient platelets exhibit reduced positive feedback loop mechanisms. This reduced reactivity is dependent on external environment and independent of hematopoietic ABCA1. BACKGROUND: The ATP-binding cassette transporter ABCA1 is required for the conversion of apolipoprotein A-1 to high-density lipoprotein (HDL), and its defect causes Tangier disease, a rare disorder characterized by an absence of HDL and accumulation of cholesterol in peripheral tissues. The role of ABCA1 in platelet functions remains poorly characterized. OBJECTIVE: To determine the role of ABCA1 in platelet functions and to clarify controversies concerning its implication in processes as fundamental as platelet phosphatidylserine exposure and control of platelet membrane lipid composition. METHODS AND RESULTS: We studied the impact of ABCA1 deficiency on platelet responses in a mouse model and in two Tangier patients. We show that platelets in ABCA1-deficient mice are slightly larger in size and exhibit aggregation and secretion defects in response to low concentrations of thrombin and collagen. These platelets have normal cholesterol and major phospholipid composition, granule morphology, or calcium-induced phosphatidylserine exposure. Interestingly, ABCA1-deficient platelets display a reduction in positive feedback loop mechanisms, particularly in thromboxane A2 (TXA2) production. Hematopoietic chimera mice demonstrated that defective eicosanoids production, particularly TXA2, was primarily dependent on external environment and not on the hematopoietic ABCA1. Decreased aggregation and production of TXA2 and eicosanoids were also observed in platelets from Tangier patients. CONCLUSIONS: Absence of ABCA1 and low HDL level induce reduction of platelet reactivity by decreasing positive feedback loops, particularly TXA2 production through a hematopoietic ABCA1-independent mechanism.

[Management of major bleeding complications and emergency surgery in patients on long-term treatment with direct oral anticoagulants, thrombin or factor-Xa inhibitors. Proposals of the Working Group on Perioperative Haemostasis (GIHP) - March 2013]. / Prise en charge des complications hémorragiques graves et de la chirurgie en urgence chez les patients recevant un anticoagulant oral anti-IIa ou anti-Xa direct. Propositions du Groupe d'intérêt en Hémostase Périopératoire (GIHP) - mars 2013.

New direct oral anticoagulants (NOAC), inhibitors of factor IIa or Xa, are expected to be widely used for the treatment of venous thromboembolic disease, or in case of atrial fibrillation. Such anticoagulant treatments are known to be associated with haemorrhagic complications. Moreover, it is likely that such patients on long-term treatment with NOAC will be exposed to emergency surgery or invasive procedures. Due to the present lack of experience in such conditions, we cannot make recommendations, but only propose management for optimal safety as regards the risk of bleeding in such emergency conditions. In this article, only dabigatran and rivaroxaban were discussed. For emergency surgery at risk of bleeding, we propose to dose the plasmatic concentration of drug. Levels inferior or equal to 30ng/mL for both dabigatran and rivaroxaban, should enable the realization of a high bleeding risk surgery. For higher concentration, it was proposed to postpone surgery by monitoring the evolution of the drug concentration. Action is then defined by the kind of NOAC and its concentration. If the dosage of the drug is not immediately available, proposals only based on the usual tests, PT and aPTT, also are presented. However, these tests do not really assess drug concentration or bleeding risk. In case of severe haemorrhage in a critical organ, it is proposed to reduce the effect of anticoagulant therapy using a nonspecific procoagulant drug (activated prothrombin concentrate, FEIBA, 30-50U/kg, or non-activated 4-factors prothrombin concentrates 50U/kg). For any other type of severe haemorrhage, the administration of such a procoagulant drug, potentially thrombogenic in these patients, will be discussed regarding concentration of NACO and possibilities for mechanical haemostasis.

[Questions--answers on the use of rivaroxaban for the treatment of venous thromboembolic disease]. / Questions - réponses sur l'utilisation du rivaroxaban pour le traitement de la maladie thromboembolique veineuse.

Rivaroxaban is a direct oral anticoagulant targeting factor Xa. Efficacy and safety of rivaroxaban were evaluated through the phase 3 EINSTEIN program, consisting in three clinical trials regarding the treatment of deep vein thrombosis (EINSTEIN DVT), pulmonary embolism (EINSTEIN PE), and in secondary prevention after a first episode of venous thromboembolic disease (EISNTEIN EXT). Rivaroxaban was recently approved both by the European and the French Health agencies for the treatment of DVT and prevention of deep vein thrombosis recurrence. This report addresses the use of rivaroxaban in clinical practice in such indications.

The Syk-kinase inhibitor R406 impairs platelet activation and monocyte tissue factor expression triggered by heparin-PF4 complex directed antibodies.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a rare but severe complication of heparin therapy in which immunoglobulin G (IgG) antibodies against the platelet factor 4-heparin complex activate platelets through the FcγRIIA receptor. Clustering of FcγRIIA initiates signaling cascades involving tyrosine kinases including the spleen tyrosine kinase (Syk). Moreover, besides the critical role of platelets, the expression of tissue factor (TF) by human monocytes triggered by HIT antibodies has been shown to contribute to the hypercoagulability and the thrombotic complications in HIT patients. OBJECTIVES: We investigated the effect of R406, a small molecule inhibitor of Syk developed as a potential treatment of autoimmune diseases, allergic disorders and B-cell related hematological malignancies, on FcγRIIA-mediated platelet activation. To further assess the potential activity of Syk inhibitors in HIT treatment, the effect of R406 was also evaluated on HIT antibodies-induced expression of TF and procoagulant activity of monocytic cells. RESULTS: We show that R406 is a potent inhibitor of platelet signaling and functions initiated by FcγRIIA cross-linking by specific antibodies or by sera from HIT patients. Syk inhibition efficiently prevents FcγRIIA-induced LAT phosphorylation and activation of phosphoinositide 3-kinase, Akt, phospholipase Cγ2 and p38 MAP-kinase. As a consequence, FcγRIIA-induced platelet aggregation, granule secretion and microparticles production are strongly inhibited by R406. Moreover, the Syk inhibitor efficiently impairs the expression of TF and the procoagulant activity of human monocytes triggered by HIT antibodies. CONCLUSION: Syk inhibitors may be of therapeutic interest in the treatment of HIT by reducing HIT antibodies-mediated platelet activation and monocyte procoagulant activity.

[Surgery and invasive procedures in patients on long-term treatment with oral direct thrombin or factor Xa inhibitors]. / Chirurgies et actes invasifs chez les patients traités au long cours par un anticoagulant oral anti-IIa ou anti-Xa direct Propositions du Groupe d'intérêt en hémostase périopératoire (GIHP) et du Groupe d'études sur l'hémostase et la thrombose (GEHT).

Direct oral anticoagulants (DOAs), inhibitors of factor IIa or Xa, are expected to replace vitamin K antagonists in most of their indications. It is likely that patients on long-term treatment with DOAs will be exposed to elective or emergency surgery or invasive procedures. Due to the present lack of experience in such conditions, we cannot make recommendations, but only propose perioperative management for optimal safety as regards the risk of bleeding and thrombosis. DOAs may increase surgical bleeding, they have no validated antagonists, they cannot be monitored by simple, standardised laboratory assays, and their pharmacokinetics vary significantly from patient to patient. Although DOAs differ in many respects, the proposals in the perioperative setting need not be specific to each. For procedures with low risk of haemorrhage, a therapeutic window of 48 h (last administration 24h before surgery, restart 24h after) is proposed. For procedures with medium or high haemorrhagic risk, we suggest stopping DOAs 5 days before surgery to ensure complete elimination of the drug in all patients. The treatment should be resumed only when the risk of bleeding has been controlled. In patients with a high risk of thrombosis (e.g. those in atrial fibrillation with an antecedent of stroke), bridging with heparin (low molecular weight, or unfractionated if the former is contraindicated) is proposed. In emergency, the procedure should be postponed for as long as possible (minimum 1-2 half-lives) and non-specific anti-haemorrhagic agents, such as recombinant human activated factor VIIa, or prothrombin concentrates, should not be given for prophylactic reversal, due to their uncertain benefit-risk.

Short-term effects of the smoke-free legislation on haemostasis and systemic inflammation due to second hand smoke exposure. The AERER study.

It was the objective of this study to assess the effect of the implementation of the smoke-free legislation on haemostasis and systemic inflammation in second-hand smoking (SHS)-exposed healthy volunteers. Fibrin-rich clot properties, platelet reactivity and inflammatory biomarkers were measured before and four months following the implementation of the smoke-free legislation in gender and age-matched healthy volunteers exposed (n=23, exposed) and unexposed (n=23, controls) to occupational SHS. The primary objective was to compare fibrin-rich clot stiffness before and after implementation of the smoke-free legislation. There was 40% reduction in fibrin-rich clot stiffness following the implementation of the smoke-free legislation in SHS-exposed volunteers (17 ± 7 vs. 10.6 ± 7 dynes/cm², before and after, respectively, p=0.001). These dramatic changes were associated with a 20% reduction in fibrin fiber density (p<0.01) and a 20% reduction in clot lysis time (p=0.05). No change in fibrin properties was observed in the control group of SHS-unexposed volunteers related to the implementation of the smoke-free legislation. Of interest, neither platelet reactivity nor systemic inflammatory biomarkers were changed in either group. The smoke-free legislation is associated with significant changes in fibrin-rich clot properties toward a less thrombogenic conformation with a better fibrinolysis response while neither platelet reactivity nor systemic inflammatory biomarkers are modified. These improvements may explain the observed reduction in acute coronary syndrome following the implementation of the smoke-free legislation.

Internalization of microparticles by endothelial cells promotes platelet/endothelial cell interaction under flow.

BACKGROUND: Microparticles (MPs) released by activated or apoptotic cells increase in number in the blood of subjects with vascular or metabolic diseases and may contribute to thrombotic complications. OBJECTIVES: In this study, we investigated whether MPs promoted platelet recruitment to endothelial cells in flow conditions, and by which mechanism. METHODS: Human umbilical vein endothelial cells (HUVECs) grown in microslide perfusion chambers were exposed to MPs prepared in vitro from HUVECs, monocytes or platelets. RESULTS: Videomicroscopy of DIOC-labelled blood perfused at arterial rate on human umbilical vein ECs demonstrated that, irrespective of their cell origin, MPs promoted the formation of platelet strings at the surface of HUVECs. This platelet/endothelial cell interaction was dependent on von Willebrand factor (VWF) expression at the HUVEC surface and involved Glycoprotein Ib and P-selectin. Interestingly, HUVECs internalized MPs within a few hours through a process involving anionic phospholipids, lactadherin and αvß3 integrin. This uptake generated the production of reactive oxygen species via the xanthine/xanthine oxidase system (inhibited by allopurinol and the ROCK inhibitor Y-27632) and the NADPH oxidase (inhibited by SOD). Reactive oxygen species appeared essential for VWF expression at the endothelial cell surface and subsequent platelet/endothelial cell interaction under flow. The pathophysiological relevance of this process is underlined by the fact that circulating MPs from Type I diabetic patients induced platelet/endothelial cell interaction under flow, with an intensity correlated with the severity of the vasculopathy.

Understanding the controversy about hormonal replacement therapy: insights from estrogen effects on experimental and clinical atherosclerosis.

Whereas hormonal replacement/menopause therapy (HRT) in post-menopausal women increases the coronary artery risk, epidemiological studies (protection in pre-menopaused women) suggest and experimental studies (prevention of the development of fatty streaks in animals) demonstrate a major atheroprotective action of estradiol (E2). The understanding of the deleterious and beneficial effects of estrogens is thus required. The immuno-inflammatory system plays a key role in the development of fatty streak deposit as well as in the atherosclerotic plaque rupture. Whereas E2 favors an anti-inflammatory effect in vitro (cultured cells), it rather elicits pro-inflammation in vivo, at the level of several subpopulations of the immuno-inflammatory system, which could contribute to plaque destabilization. Endothelium is another important target for E2, since it stimulates endothelial NO and prostacyclin production, thus promoting beneficial effects of vasorelaxation and platelet aggregation inhibition. Prostacyclin, but not NO, appears to be involved in the atheroprotective effect of E2. Estradiol accelerates also endothelial regrowth, thus favoring vascular healing. Finally, most of these effects of E2 are mediated by estrogen receptor alpha, and are independent of estrogen receptor beta. In summary, a better understanding of the mechanisms of estrogen action is required not only on the normal and atheromatous arteries, but also on innate and adaptive immune responses. This should help cardiovascular disease prevention optimization after menopause. These mouse models should help to screen existing and future Selective Estrogen Receptor Modulators (SERMs).

Detection and incidence of drug-induced agranulocytosis in hospital: a prospective analysis from laboratory signals.

AIMS: Our objectives were to assess the detection and incidence of drug-induced agranulocytosis in two university hospitals using hematology laboratory data. METHODS: A prospective study was undertaken at Toulouse University Hospital (France) and Navarra University Hospital (Spain) for 1 year (from 1 May 2004 to 30 April 2005). Using a computerized process and hematology laboratory data, all neutrophil counts with a value less than 500/mm(3) were registered, allowing identification of inpatients suffering from agranulocytosis during the period of the study. Medical records of all selected patients were then consulted. Cytostatic drugs were excluded from this study. RESULTS: During the period of the study, 225,659 neutrophil counts were performed in both hospitals, of which 2,835 (1.26%) had a neutrophil count less than 500/mm(3), corresponding to 739 patients. Seventeen patients were excluded because of lack of data, and 20 cases of infants younger than 3 months were excluded. Among the remaining patients (n = 702), 23 cases of drug-induced agranulocytosis (excluding cytostatic drugs) were suspected. All cases were classified as "serious" since they led to death in 2 cases, hospitalization or prolongation of hospitalization in 19 cases and threatening of vital prognosis in 2 cases. Withdrawal of suspected drugs was done in all cases with regression of neutropenia in 21 cases. According to hospitalization data, the annual incidence of drug-induced agranulocytosis was 1.62 (1.0-2.6) per 10,000 inpatients in Toulouse University hospital (based on 534 cases) and 3.24 (0.9-8.3) per 10,000 inpatients in Navarra University Hospital (based on 168 cases). The involved drugs were mainly antibacterial (30.4%), immunosuppressive (17.4%), antithyroid (13.0%), antiplatelet (8.7%) and nonsteroidal anti-inflammatory (8.7%) ones. Only seven cases from Toulouse University Hospital were spontaneously reported by physicians during the same period. Thus, the underreporting coefficient (U) was 2.71 (63.2%) in France. CONCLUSION: Our survey allowed us to identify the suspected drug-induced agranulocytosis through a prospective study in a large sample of inpatients using only laboratory data analysis. We also note an important underreporting rate of this serious adverse drug reaction (ADR) to the official French pharmacovigilance system. Laboratory data analysis could be used for identifying serious ADRs.