Ecarin clotting time



Ecarin clotting time (ECT) is a laboratory test used to monitor anticoagulation during treatment with hirudin, an anticoagulant medication which was originally isolated from leech saliva as well as the direct thrombin inhibitor dabigatran or pradaxa. Ecarin, the primary reagent in this assay, is derived from the venom of the saw-scaled viper, Echis carinatus.

In the clinical assay, a known quantity of eccarin is added to the plasma of a patient treated with hirudin. Ecarin activates prothrombin through a specific proteolytic cleavage, which produces meizothrombin, a prothrombin-thrombin intermediate which retains the full molecular weight of prothrombin, but possses a low level of procoagulant enzymatic activity. Crucially, this activity is inhibited by hirudin and other direct thrombin inhibitors, but not by heparin. The ECT is also unaffected by prior treatment with coumadin or the presence of phospholipid-dependant anticoagulants, such as lupus anticoagulant. Thus, the ECT is prolonged in a specific and linear fashion with increasing concentrations of hirudin.