MARKERS OF COAGULATION ACTIVATION FOR EVALUATION OF THE ANTITHROMBOTIC EFFICACY OF HEPARIN - A PROSPECTIVE-STUDY IN ACUTE DEEP VENOUS THROMBOSIS

The potential value of measurements of prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin complexes (TAT) and D-dimer for the assess ment of antithrombotic efficacy of heparin in acute deep venous thromb osis (DVT) was prospectively investigated These variables were determi ned at presentation and subsequently once daily during a course of sev en days heparin therapy. Heparin doses were adjusted according to the activated partial thromboplastin time (APTT). Compression ultrasonogra phy was performed at presentation and on day 7 to determine the extent of thrombosis according to a predefined score. Out of a total of 50 p atients accrued to the study 44 patients had reduced or unchanged exte nt of thrombosis, whereas in six patients an extension was documented. Although thrombin generation was significantly inhibited after initia tion of heparin therapy as reflected by a decrease in F1 + 2 and TAT l evels, these markers were not useful for the detection of patients wit h DVT extension. In contrast, anti-factor-Xa activities but not AMT me asurements were significantly lower in the group of patients with prop agation of DVT (median: 0.22 U/ml versus 0.38 U/ml, interquartile rang e: 0.1-0.33 U/ml versus 0.19-0.55 U/ml; P=0.001). D-dimer decreased wi thin the first days of heparin therapy but failed to indicate DVT prog ression. These data suggest that plasma anti-factor-Xa activity correl ates better with the antithrombotic efficacy of heparin than APTT meas urements and markers of coagulation or fibrinolysis activation.