Protein C response to induction of warfarin treatment after coronary bypass operation.
To investigate the effect of warfarin on the anticoagulant pathway, protein C antigen and activity levels were compared in two groups of patients treated with different regimens of sodium warfarin during the initial stage of anticoagulant therapy following heart surgery. Group I received 6 mg of warfarin per day for 3 days. Group II received 8 mg twice a day for 2 or 3 days. Preoperative levels of Protein C antigen and activity averaged 108 +/- 16% and 102 +/- 18% (mean +/- SD), respectively, and by one hour after the operation, levels had fallen significantly (protein C antigen to 76 +/- 14%; protein C activity to 70 +/- 16%). After the initiation of warfarin treatment, the levels of protein C activity in group II were significantly lower than those of group I. In contrast, the reductions in factor X were much slower and were similar in the two groups. As the factor X level reflects the antithrombotic effect of warfarin, this result suggests that the rapid reduction of protein C activity may have given rise to a transient hypercoagulable state in the patients of group II.
Iguchi
A
A
Department of Thoracic and Cardiovascular Surgery, Sendai Tokushu-kai Hospital, Japan.
Sato
K
K
D000368:Aged; D001777:Blood Coagulation / Q000187:drug effects; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D004334:Drug Administration Schedule; D005170:Factor X / Q000378:metabolism; D005260:Female; D006493:Heparin / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D011486:Protein C / Q000378:metabolism*; D013997:Time Factors; D014859:Warfarin / Q000008:administration & dosage* / Q000494:pharmacology
D011486:Protein C; D014859:Warfarin; D005170:Factor X; D006493:Heparin