Best practice & research. Clinical haematology
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Best Pract Res Clin Haematol · Jun 2013
ReviewNovel oral anticoagulants in secondary prevention of stroke.
In patients with atrial fibrillation (AF) oral anticoagulation with vitamin-K antagonists (warfarin, phenprocoumon) is effective both for primary and secondary stroke prevention yielding a 60-70% relative reduction in stroke risk compared with placebo, as well as a mortality reduction of 26 percent. Vitamin-K antagonists have a number of well documented shortcomings. Recently the results of randomised trials for three new oral anticoagulants that do not exhibit the limitations of vitamin-K antagonists have been published. ⋯ New anticoagulants add to the therapeutic options for patients with AF, and offer a number of advantages over warfarin, for both the clinician and patient, including a favorable bleeding profile and convenience of use. Aspirin is no longer an option in secondary stroke prevention in patients with atrial fibrillation. Consideration of these new anticoagulants will improve clinical decision making.
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The new oral anticoagulants (NOACs) dabigatran etexilate, rivaroxaban, and apixaban have been extensively studied for prevention and treatment of venous thromboembolic disease and for stroke prevention in atrial fibrillation. Elderly patients have the highest incidence of thrombotic complications but also have the highest risk of anticoagulant associated bleeding. In this review we critically examine the balance between risks and benefits of NOACs compared with vitamin K antagonists in elderly patients enrolled in phase 3 randomized controlled trials for the management of venous thrombosis and stroke prevention in atrial fibrillation. Results show that the favourable balance between risks and benefits of NOACs is preserved in the elderly population.
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Best Pract Res Clin Haematol · Jun 2013
ReviewDisadvantages of VKA and requirements for novel anticoagulants.
Vitamin K antagonists have been in wide use for over 70 years. Warfarin, the most commonly used vitamin K antagonist, has been shown to be highly effective in treating and preventing thrombosis. ⋯ TSOAs include the thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban, apixaban). This chapter reviews the disadvantages of warfarin and evaluates both the advantages and disadvantages of the new oral anticoagulants.
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The risk of venous thrombosis extends for an indeterminate length of time following admission to hospital with a medical or surgical condition. Observational studies in surgery show this risk extends for months and perhaps more than one year, for medical patients the risk extends for at least several weeks. Large bodies of evidence support the heightened risk status of hospitalised surgical and medical patients, and that prophylactic measures significantly reduce the risk of thrombosis. ⋯ Hence no therapies are approved for prolonged thromboprophylaxis in medical patients. In this area there have been one phase III study of low molecular weight heparin and two completed phase III studies of NOACs. This article briefly summarises our understanding of the background to preventing venous thromboembolism in hospitalised medical patients and reviews the details of the studies using NOACs.
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In the past decade, several new oral anticoagulants (NOACs) have been studied and approved for the prophylaxis and treatment of arterial and venous thromboembolism. These agents were shown to be as effective as or better than warfarin and resulted in comparable or lower bleeding rates than warfarin. Specific antidotes for the reversal of the anticoagulant effect of these drugs, such as monoclonal antibodies against the direct thrombin inhibitor dabigatran or recombinant Xa-analog in the case of factor Xa inhibitors, are still being investigated in early clinical trials. ⋯ Activated prothrombin complex concentrate seems promising for the reversal of dabigatran, while non-activated prothrombin complex concentrates have potential for the reversal of anti-factor Xa. The risk of thromboembolic complications requires careful evaluation. In this article, the evidence- or the lack of it - supporting the use of the different prohemostatic agents for the management of bleeding and for reversal of the different classes of NOACs is discussed.