Gilles Pernod

Effect of non-specific reversal agents on anticoagulant activity of dabigatran and rivaroxaban: a randomised crossover ex vivo study in healthy volunteers.

The new anticoagulants dabigatran and rivaroxaban can be responsible for haemorrhagic complications. As for any anticoagulant, bleeding management is challenging. We aimed to test the effect of all putative haemostatic agents on the anticoagulant activity of these new drugs using thrombin generation tests. In an ex vivo study, 10 healthy white male subjects were randomised to receive rivaroxaban (20 mg) or dabigatran (150 mg) in one oral administration. After a two weeks washout period, they received the other anticoagulant. Venous blood samples were collected just before drug administration (H0) and 2 hours thereafter. Reversal of anticoagulation was tested in vitro using prothrombin complex concentrate (PCC), rFVIIa or FEIBA® at various concentrations. Rivaroxaban affects quantitative and kinetic parameters, including the endogenous thrombin potential (ETP-AUC and more pronouncedly the thrombin peak), the lag-time and time to peak. PCC strongly corrected ETP-AUC, whereas rFVIIa only modified the kinetic parameters. FEIBA corrected all parameters. Dabigatran specially affects the kinetics of thrombin generation with prolonged lag-time and time to peak. Although PCC increased ETP-AUC, only rFVIIa and FEIBA corrected the altered lag-time. For both anticoagulants, lower doses of FEIBA, corresponding to a quarter to half the dose usually used, have potential reversal profile of interest. In conclusion, some non-specific reversal agents appear to be able to reverse the anticoagulant activity of rivaroxaban or dabigatran. However, clinical evaluation is needed regarding haemorrhagic situations, and a meticulous risk-benefit evaluation regarding their use in this context is required.

Common susceptibility alleles are unlikely to contribute as strongly as the FV and ABO loci to VTE risk: results from a GWAS approach.

Venous thromboembolism (VTE) is a complex disease that has a major genetic component of risk. To identify genetic factors that may modify the risk of VTE, we conducted a genome-wide association study by analyzing approximately 317 000 single nucleotide polymorphisms (SNPs) in 453 VTE cases and 1327 controls. Only 3 SNPs located in the FV and ABO blood group genes were found associated with VTE at a genome-wide significant level of 1.7 x 10(-7). Detailed analysis of these SNPs in additional cohorts of more than 1700 cases and 1400 controls revealed that the association observed at the FV locus was the result of the increased risk mediated by the FV Leiden mutation, whereas O and A2 blood groups were found to be at lower risk for VTE. Apart from the FV and ABO loci, no other locus was found strongly associated with VTE. However, using this large cohort of subjects, we were able to replicate the mild effects of 2 nonsynonymous SNPs, rs1613662 in GP6 and rs13146272 in CYP4V2, recently suspected to be associated with VTE.

Surgery and invasive procedures in patients on long-term treatment with direct oral anticoagulants: thrombin or factor-Xa inhibitors. Recommendations of the Working Group on Perioperative Haemostasis and the French Study Group on Thrombosis and Haemostasis.

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

EDUC'AVK: Reduction of Oral Anticoagulant-related Adverse Events After Patient Education: A Prospective Multicenter Open Randomized Study.

BackgroundLong-term oral anticoagulation treatment is associated with potential morbidity. Insufficient patient education is linked to poorly controlled anticoagulation. However the impact of a specific educational program on anticoagulation related morbidity remains unknown.ObjectiveTo evaluate the effect of an oral anticoagulation patient education program in reducing both hemorrhagic and recurrent thrombotic complications.Design/ParticipantsWe conducted a prospective, multicenter open randomized study, comparing an interventional group who received a specific oral anticoagulation treatment educational program with a control group. Eligible patients were older than 18 and diagnosed as having deep vein thrombosis or pulmonary embolism requiring therapy with a vitamin K antagonist for 3 months or more. Our primary outcome was the occurrence of hemorrhagic or thromboembolic events.ResultsDuring the 3-month follow-up the main outcome criteria were observed 20 times (6.6% of patients), 5 (3.1%) in the experimental and 15 (10.6%) in the control group. Consequently, in multivariate analysis, the cumulative risk reduction in the experimental group was statistically significant (OR 0.25, 95% CI 0.1 – 0.7, p < 0.01).ConclusionsPatient education using an educational program reduced VKA-related adverse event rates.

A Follow-Up Study of a Genome-wide Association Scan Identifies a Susceptibility Locus for Venous Thrombosis on Chromosome 6p24.1

To identify genetic susceptibility factors conferring increased risk of venous thrombosis (VT), we conducted a multistage study, following results of a previously published GWAS that failed to detect loci for developing VT. Using a collection of 5862 cases with VT and 7112 healthy controls, we identified the HIVEP1 locus on chromosome 6p24.1 as a susceptibility locus for VT. Indeed, the HIVEP1 rs169713C allele was associated with an increased risk for VT, with an odds ratio of 1.20 (95% confidence interval 1.13-1.27, p = 2.86 x 10(-9)). HIVEP1 codes for a protein that participates in the transcriptional regulation of inflammatory target genes by binding specific DNA sequences in their promoter and enhancer regions. The current results provide the identification of a locus involved in VT susceptibility that lies outside the traditional coagulation/fibrinolysis pathway.

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.

Quantitative high D-dimer value is predictive of pulmonary embolism occurrence independently of clinical score in a well-defined low risk factor population

Summary.  We performed a prospective study to assess whether positive quantitative D‐dimer (DD) levels could be integrated for a selected population in a defined strategy to accurately diagnose pulmonary embolism (PE). For this purpose, 1528 in‐ or outpatients with clinically suspected PE were investigated according to our prescription rules. Clinical probability was defined as low, intermediate or high. Patients in whom DD levels were measured met criteria defined by our previously described decision‐making algorithm: in‐ and outpatients, < 80 years, without surgery in the previous 30 days or active cancer. Nine hundred and twenty‐three patients (60.4%) had quantitative DD measurement using automated latex DD assay (STA‐Liatest D‐Di®). According to our decision‐making algorithm, DD measurement was applied to 70.5% of out‐, and 55.7% of inpatients, and PE diagnosis was ruled out in 49.5% of the 923 patients. This allowed us to confirm prospectively that our specific rules greatly improve the DD testing efficiency. PE was diagnosed in 115 (12.5%) patients. For a 0.5 mg L−1 cut‐off, the test sensitivity was 97.4%, but its specificity was only 56.7%. However, PE prevalence increased gradually with DD levels. The true observed PE prevalence, according to the quantitative assessment of DD levels, differed from that predicted with pretest clinical probability only. Moreover, in this well‐defined patient group, a quantitative DD level > 2 mg L−1 was predictive of PE occurrence independently of the clinical score (odds ratio 6.9, 95% confidence interval 3.7, 12.8). As part of a defined strategy, knowledge of positive DD quantitative value, together with the clinical probability score, improves the PE predictive model. A clinical validation of these results in a follow‐up study would now be necessary before considering the implementation of this strategy into clinical practice.

Gas chromatographic–mass spectrometric determination of total homocysteine in human plasma by stable isotope dilution: method and clinical applications

The detection and quantitation of slight increases of plasma homocysteine levels is of growing interest. This has prompted us to develop a highly sensitive and accurate capillary gas chromatography-mass spectrometry (GC-MS) method. The method proved to be highly sensitive (DL=0.17 micromol/l) with between- and within-run precision less than 6% and 7%, respectively. Reference values of plasma total homocysteine have been determined for men (n=39) and women (n=36), showing a significant difference (P=0.003) between gender. Preliminary results in cerebrovascular accidents and in venous thrombosis are presented.

A multi‐stage multi‐design strategy provides strong evidence that the BAI3 locus is associated with early‐onset venous thromboembolism

Summary.  Background: Factor VIII (FVIII) and von Willebrand factor (VWF) are two known quantitative risk factors for venous thromboembolism (VTE). Objectives: To identify new loci that could contribute to VTE susceptibility and to modulating FVIII and/or VWF levels. Patients/Methods: A pedigree linkage analysis was first performed in five extended French‐Canadian families, including 253 individuals, to identify genomic regions linked to FVIII or VWF levels. Identified regions were further explored using ‘in silico’ genome‐wide association studies (GWAS) data on VTE (419 patients and 1228 controls), and two independent case‐control studies (MARTHA and FARIVE) for VTE, gathering 1166 early‐onset patients and 1408 healthy individuals. Single nucleotide polymorphisms (SNPs) associated with VTE risk were further investigated in relation to plasma levels of FVIII and VWF in a cohort of 108 healthy nuclear families. Results: Four main linkage regions were identified, among which the well‐characterized ABO locus, the recently identified STAB 2 gene, and a third one, on chromosome 6q13‐14, harbouring four non‐redundant SNPs, associated with VTE at P < 10−4 in the GWAS dataset. The association of one of these SNPs, rs9363864, with VTE was further replicated in the MARTHA and FARIVE studies. The rs9363864‐AA genotype was associated with a lower risk for VTE (OR = 0.58 [0.42–0.80], P = 0.0005) but mainly in non‐carriers of the FV Leiden mutation. This genotype was further found to be associated with the lowest levels of FVIII (P = 0.006) and VWF (P = 0.001). Conclusions: The BAI3 locus where the rs9363864 maps is a new candidate for VTE risk.

Accuracy of complete compression ultrasound in ruling out suspected deep venous thrombosis in the ambulatory setting - A prospective cohort study

Evidence on the safety of complete compression ultrasound for ruling out deep venous thrombosis (DVT) is derived from studies conducted in tertiary care centers, although most patients with suspected DVT are managed in the ambulatory office setting. It was the objective of this study to estimate the rate of venous thromboembolism when anticoagulant therapy is withheld from ambulatory patients with normal findings on a single complete compression ultrasound. As part of a prospective cohort study, 3,871 ambulatory patients with clinically suspected DVT were enrolled by 255 board-certified vascular medicine physicians practicing in private offices in France. Compression ultrasound of the entire lower extremities was performed using a standardised examination protocol. Anticoagulant therapy was withheld from patients with negative findings on compression ultrasound, and 1,254 of them were randomly selected for follow-up. The main outcome measure was the three-month incidence of symptomatic venous thromboembolic events confirmed by objective testing. DVT was detected in 1,023 patients (26.4%), including 454 (11.7%) and 569 (14.7%) cases of proximal and isolated distal DVT, respectively. Of the 1,254 patients with negative results sampled for follow-up, six received anticoagulant therapy during follow-up and five were lost to follow-up. Five of 1,243 patients (0.4%, 95% confidence interval [CI], 0.1-0.9) experienced non-fatal symptomatic venous thromboembolic events (pulmonary embolism in two patients and DVT in three patients) and eight of 1,254 patients (0.6%, 95% CI, 0.3-1.2) died during the three-month follow-up. In conclusion, anticoagulant therapy can be safely withheld after negative complete compression ultrasound without further testing in the ambulatory office setting.