Fibrinolytic activity in patients with idiopathic and secondary deep venous thrombosis

Decreased fibrinolytic activity (FA) is considered a risk factor in the development of deep venous thrombosis (DVT). The purpose of this study was to test the hypothesis that an abnormally low FA is more likely in idiopathic DVT as opposed to DVT in the presence of other predisposing risk factors. 156 patients were studied three months after an acute DVT confirmed by venography. In 82 patients a predisposing factor such as trauma, surgery or malignancy was present. In 74, DVT was idiopathic. Fibrinolytic activity was measured in all patients using the following tests: 1. Euglobulin Lysis Time (ELT, in minutes). 2. Global Fibrinolytic activity (FA in mg fibrin lysed per hour). ELT measures plasminogen activator activity (PAA) while FA which is a more global test measures the net effect of the PAA, the plasminogen activator inhibitor (PAI) and the clot structure. PAI was measured in 67 patients from both groups using an Enzyme-Linked immunosorbent assay (ELISA). The results obtained show a significant increase in the incidence of abnormal FA and ELT in the idiopathic group. This supports the hypothesis that low FA is an aetiological factor in the development of idiopathic DVT. The results also demonstrate the importance of associating the FA test to the classical tests such as ELT, PA and PAI for the detection of hypofibrinolysis.