Hypercoagulable state under low-intensity warfarin anticoagulation assessed with hemostatic markers in cardiac disorders.

The hemostatic condition under low-intensity anticoagulation in cardiac disorders is not fully elucidated. The aim of this study was to ascertain whether hemostatic molecular markers are a useful assessment for anticoagulation to detect the hypercoagulable state. A hematologic study was performed in 75 outpatients, without thromboembolic episodes, treated with low-intensity anticoagulation (average international normalized ratio [INR] 1.72) because of potential cardiac sources of arterial emboli, and in 40 age-matched control subjects. The average level of thrombin-antithrombin III complex (TAT) was significantly lower in patients than in control subjects (p = 0.005), and the mean value of D-dimer was not statistically different between patients and control subjects. Although TAT correlated moderately with D-dimer (r = 0.45, p = 0.0001), INR did not correlate with TAT or D-dimer. Elevated TAT > 3.0 ng/ml and/or D-dimer S 150 ng/ml were observed in 15 patients (20.0%), whereas the remaining 60 patients (80.0%) had no obvious increase in the level of TAT or D-dimer at overall INR. Antithrombin III activity did not correlate significantly with INR, but protein C activity and free protein S antigen showed a significant negative relation to INR (r = 0.82, r = 0.62, respectively, p = 0.0001). Low-intensity anticoagulation was sufficient to reduce coagulation and subsequent fibrinolytic activation in cardiac disorders, but may not be sufficient in some patients with elevated TAT or D-dimer concentration.(ABSTRACT TRUNCATED AT 250 WORDS)