ABSTRACT
The fast offset of action of the direct oral anticoagulants represents an advantage over Vitamin K Antagonists (VKA), whenever a patient under oral anticoagulation has to undergo surgery or intervention. Blood coagulation involves complex interactions between platelets, endothelium, endogenous procoagulant and anticoagulant proteins, and fibrinolytic factors to respond to acute vascular damage as well as to prevent excessive propagation of thrombus. VKA do not directly interfere with the coagulation process, but act indirectly by preventing the biosynthesis of fully active coagulation factors II, VII, IX, and X as well as of the endogenous anticoagulants protein C and protein S. The action and thus the bleeding risk are, of course, enhanced by other antithrombotics, but also by compounds reducing the coagulation factor synthesis or by reducing the availability of vitamin K. Additionally, the vitamin K content of food modulates the anticoagulation by VKA.
