Soluble fibrin and X-oligomer levels following streptokinase therapy of acute myocardial infarction: Dominance of coagulation over fibrinolysis beyond twelve hours

Background: Raised levels of platelet activation markers and evidence for thrombin generation following thrombolysis have suggested that there is activation of coagulation as a consequence of therapy. Soluble fibrin is an early product of coagulation activity, and X-oligomer is an early product of fibrinolytic activity. Methods: Soluble fibrin and X-oligomer were measured by ELISA in 27 patients (20 male, ages 46-84 years - mean 68) receiving streptokinase for myocardial infarction. Samples were taken prior to therapy and at 1,2, 4, 12, 24, 36 and 48 hours. Samples were taken into citrate, citrate plus aprotinin, or citrate plus aprotinin and hirudin. Results: Results are for citrated samples as no significant difference was noted between the anticoagulants employed. Soluble fibrin was raised at presentation (mean 31.75 U/mL). Our data from several hundred samples suggest a normal range of < 5 U/mL. Soluble fibrin fell significantly immediately following thrombolysis (mean 0.16 U/mL; p = 0.0001, pré vs. 1 hour), and remained low until 12 hours when levels steadily rose to a mean of 17.69 U/mL at 48 hours (P = 0.0001, 4 vs. 48 hours). X-oligomer remained within our normal range (<300 ng/mL) throughout, but fell in the first hour (P = 0.001, pre vs. 1 hour), rose to peak at 12 hours (P = 0.0001, 1 hour vs. 12 hours), and then fell to 48 hours (P = 0.01, 12 hour vs. 48 hour). Conclusions: Initial falls in soluble fibrin reflect plasmin activity. The initial falls in X-oligomer suggests plasmin degradation of this product also. The later rise of soluble fibrin suggests true activation of coagulation beyond 12 hours. This is mirrored by a fall in X-oligomer suggesting a dominance beyond 12 hours of coagulation over fibrinolysis.