title: Evaluation of the blood coagulation mechanism and platelet aggregation in individuals with mechanical or biological heart prostheses.
abstract: Oral anticoagulants have been widely employed to decrease thrombotic risk by reducing the levels of vitamin K-dependent clotting factors. Paradoxically, the use of oral anticoagulants also decreases the levels of natural anticoagulants (protein C and protein S), which favors the hypercoagulability state. Increased platelet activation has been reported in patients undergoing warfarin treatment. These findings have raised questions about the antagonistic effect of oral anticoagulants and their implications for hemostatic balance. The aim of this study is to determine the relationship between warfarin dosage and prothrombin time [International Normalized Ratio (INR)], platelet aggregation, vitamin K-dependent clotting factors, and protein C and protein S. Blood samples from 27 patients were analyzed, seven with mechanical prostheses and 20 with biological prostheses, and 27 controls. Multiple regression analysis showed that factor II most significantly determines the INR. Results showed that the INR, clotting factors, and protein C and protein S activity did not correlate with warfarin dosage, highlighting the need for accurate laboratory monitoring of those undergoing anticoagulant therapy.
authors.affiliation: Department of Clinical and Toxicological Analysis, Faculty of Pharmacy, Federal University of Minas Gerais, Brazil.
authors.forename: C N
authors.initials: CN
authors.lastname: Ferreira
authors.forename: L M
authors.initials: LM
authors.lastname: Vieira
authors.forename: L M S
authors.initials: LM
authors.lastname: Dusse
authors.forename: C V
authors.initials: CV
authors.lastname: Reis
authors.forename: C F S
authors.initials: CF
authors.lastname: Amaral
authors.forename: W A M
authors.initials: WA
authors.lastname: Esteves
authors.forename: L M A
authors.initials: LM
authors.lastname: Fenelon
authors.forename: M G
authors.initials: MG
authors.lastname: Carvalho
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000925:Anticoagulants / Q000494:pharmacology / Q000627:therapeutic use*; D001241:Aspirin / Q000494:pharmacology / Q000627:therapeutic use; D001777:Blood Coagulation / Q000187:drug effects / Q000502:physiology*; D019774:Blood Coagulation Factor Inhibitors / Q000378:metabolism; D001779:Blood Coagulation Factors / Q000378:metabolism; D001780:Blood Coagulation Tests; D016022:Case-Control Studies; D004341:Drug Evaluation; D005260:Female; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology*; D014859:Warfarin / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000925:Anticoagulants; D019774:Blood Coagulation Factor Inhibitors; D001779:Blood Coagulation Factors; D014859:Warfarin; D001241:Aspirin