[Significance of combined use of anticoagulants and antiplatelet agents in the early stage after prosthetic valve replacement].

Patients who had undergone prosthetic valve replacement were treated with warfarin (anticoagulant) alone or in combination of ticlopidine (200 mg/day) or aspirin (81 mg/day) (anti-platelet agents). The study of blood coagulation factors and platelet aggregation were carried out with these cases. 1) The patients (n = 24) receiving warfarin for 21 days after prosthetic valve replacement revealed marked increases in PIVKA-II and vitamin K1-epoxide. The protein C activity was significantly lower than that before the operation. High levels of more than 5 ng/ml of TAT were found before operation and after warfarin administration for 21 days. 2) Warfarin did not affect platelet aggregation, whereas ticlopidine inhibited ADP-induced platelet aggregation and aspirin inhibited both collagen-induced and arachidonic acid-induced aggregation. In conclusion, combined use of anticoagulants and antiplatelet agents after prosthetic valve replacement will suppress not only the blood coagulation but also the platelet aggregation systems.