HEMOSTATIC VARIABLES IN PATIENTS WITH UNSTABLE ANGINA

To assess the contribution of thrombus formation in the pathogenesis o f unstable angina, we employed the recently developed assays of small fragments which reflect the degree of activation of various components of the haemostatic system. Such haemostatic measurements were underta ken in patients with unstable angina (n = 47) from the time of their a dmission to the coronary care unit (CCU) at 8-h intervals in the first 24 h and then daily for a total of 5 days. The results obtained were compared with healthy control values. Patients exhibited lower ATIII, prolongation of the APTT and TT, but not PT or the reptilase time, whi ch is a consequence of heparinization. There was significant elevation of fibrinogen, factor VIII:C, von Willebrand factor:antigen and von W illebrand factor:ristocetin cofactor throughout the study period. Ther e was also evidence of thrombin generation as indicated by the elevate d levels of fibrinopeptide A (FPA) and thrombin-antithrombin complexes . The platelet release proteins, beta-thromboglobulin (BTG) and platel et factor 4 (PF4), were markedly elevated in the first 2 days and drop ped gradually thereafter. The fibrinolytic inhibitor, plasminogen acti vator inhibitor (PAI), levels were elevated throughout. Proteins C and S, plasminogen and alpha2-antiplasmin remained unchanged. It was conc luded that in patients with unstable angina, there is significant acti vation of the clotting system and inhibition of fibrinolysis which con firms the existence of a tendency towards thrombus formation in patien ts with unstable angina.