Influence of heparin treatment on biochemical markers of an activation of the coagulation system

Abstract

Monitoring of anticoagulant treatment is not yet satisfactory. Otherwise optimal treatment control in special situations as low dose heparin prophylaxis in hip surgery or high dose anticoagulant treatment in patients after coronary stent implantation may be desirable. Recently available thrombin markers were analyzed in 51 patients under low dose (group 1) and 30 patients under high dose therapy with unfractionated heparin (group 2a and b) as well as in controls (n=26). Before therapy these parameters were significantly elevated in both patient groups. Elevated thrombin-antithrombin III-complexes (TAT) despite adequate prolongation of aPTT under high dose heparin in 38.2% of patients indicate that therapeutic concentrations of heparin in these cases are insufficient for depressing this parameter completely. During low dose therapy only prothrombin fragment (F1+2) significantly decreased. This may be explained by catalytic induction of TAT-complex formation by heparin. Decrease of D-Dimer under heparin therapy in both groups does not parallel with TAT and F1+2 but was more prolonged. This can be explained by dependence of the D-Dimer level on spontaneous fibrinolytic activity and by a longer plasma half-life as well as a chronic and continuous fibrinolytic process in an older thrombus. In conclusion, thrombin markers seem to be helpful in estimating anticoagulant treatment efficacy. As a consequence, anticoagulant treatment has to be intensified in high-risk patients for complete depression of these markers. Whether the benefit of higher heparin doses is worth the risk of drug-induced hemorrhage, however, remains to be clarified in clinical studies.