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The Risk of Bleeding with Long-Term Oral Anticoagulation

Andrea Rubboli, MD, FESC

Long-term oral anticoagulation with vitamin K antagonists (VKAs) is the established antithrombotic regimen for the prevention of thromboembolic complications in various clinical conditions such as atrial fibrillation (AF) and venous thromboembolism (VTE), and in the presence of prosthetic heart valves. The anticoagulant effect of VKAs is the consequence of their interference with the cyclic interconversion of vitamin K and its epoxide, which, in turn, is caused by inhibition of the vitamin K epoxide reductase (VKORC1) enzyme (Figure 1) [1]. As a result, VKAs block vitamin K reduction, which is essential for the γ-carboxylation of vitamin K-dependent coagulation factors, including factors II, VII, IX, and X (Figure 1) [1]. While acenocoumarol and phenprocoumon are preferred in some countries, warfarin is the VKA most commonly used in clinical practice [1].

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