[Oral anticoagulat treatment in venous thromboembolic disease]

Coumarin or anti-vitamin K oral anticoagulants have been used in anticoagulation therapy for more than 50 years. Well-designed studies have demonstrated the effectiveness of these drugs in the primary and secondary prevention of venous thromboembolic disease (VTD). Because of greater life expectancy and the increase in the indications for oral anticoagulation therapy (OAT), more and more patients are receiving this type of treatment. In Spain, approximately 1% of the population receives OAT. The mechanism of action of coumarin anticoagulants is based on inhibition of the interconversion of vitamin K and its 2,3-epoxide (vitamin K epoxide, which modulates gamma-carboxylation of the glutamic acid residues in the N-terminal regions of vitamin-K-dependent factors, namely, II, VII, IX, X, protein C, protein S and protein Z). Due to the lack of gamma-carboxylation, these factors lose their procoagulant activity. Major hemorrhagic complications of OAT in VTD after 3-6 months of treatment, with an INR of 2-3, occur in nearly 2% of patients. The hemorrhagic complications of OAT are related to the intensity of anticoagulation, patient characteristics, the concomitant use of drugs that interfere with hemostasis, and treatment duration. The risk of VTD recurrence after 3-6 months of OAT is high and can be more than 10% in patients with idiopathic thromboembolism or irreversible risk factors such as thrombophilia, cancer and other situations conferring permanent risk. The risk of recurrence is more frequent in men, in patients with thrombophilia especially in antithrombin deficiency, and in patients with cancer, residual venous obstruction, or elevated D dimer.