The potential value of measurements of
prothrombin fragment 1 + 2 (F1 + 2),
thrombin-
antithrombin complexes (TAT) and
D-dimer for the assessment of antithrombotic efficacy of
heparin in acute
deep venous thrombosis (DVT) was prospectively investigated. These variables were determined at presentation and subsequently once daily during a course of seven days
heparin therapy.
Heparin doses were adjusted according to the activated partial thromboplastin time (APTT). Compression ultrasonography 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 patients accrued to the study 44 patients had reduced or unchanged extent of
thrombosis, whereas in six patients an extension was documented. Although
thrombin generation was significantly inhibited after initiation of
heparin therapy as reflected by a decrease in F1 + 2 and TAT levels, these markers were not useful for the detection of patients with DVT extension. In contrast, anti-
factor-Xa activities but not APTT measurements were significantly lower in the group of patients with propagation of DVT (median: 0.22 U/ml versus 0.38 U/ml, interquartile range: 0.1-0.33 U/ml versus 0.19-0.55 U/ml; P = 0.001).
D-dimer decreased within the first days of
heparin therapy but failed to indicate DVT progression. These data suggest that plasma anti-
factor-Xa activity correlates better with the antithrombotic efficacy of
heparin than APTT measurements and markers of coagulation or fibrinolysis activation.