Heparanase procoagulant activity is elevated in women using oral contraceptives.

STUDY QUESTION: What is the effect of estrogen on heparanase procogulant activity? SUMMARY ANSWER: Estrogen increases heparanase procoagulant activity. WHAT IS KNOWN ALREADY: Estrogen therapy increases the risk of thrombosis and was previously found to up-regulate heparanase expression. Heparanase is involved in angiogenesis and metastasis, and has been shown to form a complex with tissue factor (TF) and also shown to enhance the generation of factor Xa. STUDY DESIGN, SIZE, DURATION: A case-control study. Thirty-four healthy women using oral contraceptives (OC) and 41 women not using hormonal therapy and not pregnant per history were enrolled, over a 5-month period, at the Rambam Medical Center, Haifa, Israel. In vitro, estrogen receptor-positive (MCF-7) and -negative (MDA-231) cell lines were incubated with estrogen, tamoxifen and ICI-182.780 a pure estrogen receptor antagonist. The cell medium was evaluated for TF/heparanase complex activity, TF activity and heparanase procoagulant activity by chromogenic substrate. PARTICIPANTS/MATERIALS, SETTING, METHODS: Exclusion criteria included age <18 years, post-menopausal women, concomitant medications other than supplement minerals and vitamins, acute or chronic illness. MAIN RESULTS AND THE ROLE OF CHANCE: The study demonstrates increased risk of high heparanase procoagulant activity in OC users. When a cutoff level of 0.25 (absorbance 405-490 nm) was set, the odds ratio was 131 (P < 0.0001). When all results were studied by quartiles, in quartiles 3 and 4 the results were almost exclusively of the OC users (P < 0.0001). In cell cultures, estrogen and tamoxifen increased heparanase procoagulant activity in the medium of estrogen receptor-positive (MCF-7) cells. LIMITATIONS, REASONS FOR CAUTION: The main limitation of the current study is that the two estrogens given to the women and cell cultures, ethinyl estradiol (EE) and 17-ß-estradiol (E2), respectively, may have different effects on the coagulation system, although an increase in heparanase procoagulant activity was demonstrated in both of them. Although the sample size of the study group was limited, significant differences in the activation of the extrinsic coagulation pathway were demonstrated. WIDER IMPLICATIONS OF THE FINDINGS: The clinical relevance of the heparanase procoagulant activity assay as a screening tool in thrombophilia work-up should further be elucidated.

The promise of novel direct oral anticoagulants.

The standard effective treatment of venous and arterial thromboembolism includes unfractionated and low-molecular weight heparin as well as warfarin, which have major disadvantages. In recent years, new anticoagulants have been developed in an attempt to overcome the known limitations of established treatment and develop improved therapies. This chapter reviews pharmacological properties of the new anticoagulants, the most recent trials assessing their safety and efficacy as well as potential advantages and disadvantages of using these novel drugs in real life.

Oral rivaroxaban for symptomatic venous thromboembolism.

BACKGROUND: Rivaroxaban, an oral factor Xa inhibitor, may provide a simple, fixed-dose regimen for treating acute deep-vein thrombosis (DVT) and for continued treatment, without the need for laboratory monitoring. METHODS: We conducted an open-label, randomized, event-driven, noninferiority study that compared oral rivaroxaban alone (15 mg twice daily for 3 weeks, followed by 20 mg once daily) with subcutaneous enoxaparin followed by a vitamin K antagonist (either warfarin or acenocoumarol) for 3, 6, or 12 months in patients with acute, symptomatic DVT. In parallel, we carried out a double-blind, randomized, event-driven superiority study that compared rivaroxaban alone (20 mg once daily) with placebo for an additional 6 or 12 months in patients who had completed 6 to 12 months of treatment for venous thromboembolism. The primary efficacy outcome for both studies was recurrent venous thromboembolism. The principal safety outcome was major bleeding or clinically relevant nonmajor bleeding in the initial-treatment study and major bleeding in the continued-treatment study. RESULTS: The study of rivaroxaban for acute DVT included 3449 patients: 1731 given rivaroxaban and 1718 given enoxaparin plus a vitamin K antagonist. Rivaroxaban had noninferior efficacy with respect to the primary outcome (36 events [2.1%], vs. 51 events with enoxaparin-vitamin K antagonist [3.0%]; hazard ratio, 0.68; 95% confidence interval [CI], 0.44 to 1.04; P<0.001). The principal safety outcome occurred in 8.1% of the patients in each group. In the continued-treatment study, which included 602 patients in the rivaroxaban group and 594 in the placebo group, rivaroxaban had superior efficacy (8 events [1.3%], vs. 42 with placebo [7.1%]; hazard ratio, 0.18; 95% CI, 0.09 to 0.39; P<0.001). Four patients in the rivaroxaban group had nonfatal major bleeding (0.7%), versus none in the placebo group (P=0.11). CONCLUSIONS: Rivaroxaban offers a simple, single-drug approach to the short-term and continued treatment of venous thrombosis that may improve the benefit-to-risk profile of anticoagulation. (Funded by Bayer Schering Pharma and Ortho-McNeil; ClinicalTrials.gov numbers, NCT00440193 and NCT00439725.).

Extended duration rivaroxaban versus short-term enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a double-blind, randomised controlled trial.

BACKGROUND: The risk of venous thromboembolism is high after total hip arthroplasty and could persist after hospital discharge. Our aim was to compare the use of rivaroxaban for extended thromboprophylaxis with short-term thromboprophylaxis with enoxaparin. METHODS: 2509 patients scheduled to undergo elective total hip arthroplasty were randomly assigned, stratified according to centre, with a computer-generated randomisation code, to receive oral rivaroxaban 10 mg once daily for 31-39 days (with placebo injection for 10-14 days; n=1252), or enoxaparin 40 mg once daily subcutaneously for 10-14 days (with placebo tablet for 31-39 days; n=1257). The primary efficacy outcome was the composite of deep-vein thrombosis (symptomatic or asymptomatic detected by mandatory, bilateral venography), non-fatal pulmonary embolism, and all-cause mortality up to day 30-42. Analyses were done in the modified intention-to-treat population, which consisted of all patients who had received at least one dose of study medication, had undergone planned surgery, and had adequate assessment of thromboembolism. This study is registered at ClinicalTrials.gov, number NCT00332020. FINDINGS: The modified intention-to-treat population for the analysis of the primary efficacy outcome consisted of 864 patients in the rivaroxaban group and 869 in the enoxaparin group. The primary outcome occurred in 17 (2.0%) patients in the rivaroxaban group, compared with 81 (9.3%) in the enoxaparin group (absolute risk reduction 7.3%, 95% CI 5.2-9.4; p<0.0001). The incidence of any on-treatment bleeding was much the same in both groups (81 [6.6%] events in 1228 patients in the rivaroxaban safety population vs 68 [5.5%] of 1229 patients in the enoxaparin safety population; p=0.25). INTERPRETATION: Extended thromboprophylaxis with rivaroxaban was significantly more effective than short-term enoxaparin plus placebo for the prevention of venous thromboembolism, including symptomatic events, in patients undergoing total hip arthroplasty.