A Novel Assay to Detect Alterations of Coagulation and Fibrinolysis after Coronary Artery Bypass Surgery

Abstract

Background: A fine balance between pro- and anti-coagulant factors is required to prevent bleeding and graft (or other) thrombosis in the period that follows coronary artery bypass grafting (CABG). The majority of routinely available tests can adequately detect clinical states of hypocoagulability but fail to detect states of hypercoagulability. The overall haemostatic potential (OHP) assay, which measures coagulation and fibrinolysis, has been used to detect the presence and cause of hypercoagulable states in a variety of patients – those with arterial and venous thromboembolism, autoimmune disease and disorders of pregnancy. We performed the assay on the plasma of patients before and after CABG. Methods: Plasma was collected from patients before and on days 1, 3 and 5 after both CABG and off-pump CABG (OPCAB). An anti-fibrinolytic agent was given routinely during CABG. By adding a combination of tissue factor and tissue plasminogen activator to plasma and buffer, the formation and degradation of fibrin clot was measured by spectrophotometry. Results: There was significant increase in the coagulation potential on days 3 and 5 after surgery in both groups (p < 0.0001 for both groups, no difference between groups). Fibrinolysis was significantly impaired after CABG on days 1, 3 and 5 but not after OPCAB (p < 0.0001, p = 0.57 respectively). Conclusion: Patients in the period after CABG are in a hypercoagulable state. This is a result of both an increase in coagulation potential and impairment of fibrinolysis.