Coagulation system activity before coronary artery bypass surgery for unstable angina.

Objective: To measure coagulation activity immediately prior to coronary artery bypass surgery. Previous reports have shown that a hypercoagulable state and reduced fibrinolytic activity increase the risk of postoperative graft failure.

Design: Fifty patients with unstable angina and ongoing low-molecular-weight heparin antithrombotic treatment for a median of 4 days and 25 stable patients undergoing elective surgery were included.

Results: Antithrombin levels were significantly lower whereas fibrinogen and plasminogen activator inhibitor-1 levels were higher in the unstable patients than in the stable patients. Median preoperative levels of thrombin-antithrombin complex (TAT), prothrombin fragment1+2 (F1+2), fibrin D-dimers and beta-thromboglobulin did not differ significantly in unstable and stable patients. There were signs of activated coagulation with elevated levels of TAT and F1+2 before the operation in half of the unstable patients, who had had chest pain at rest within 48 h preceding the operation and also in one-third of patients undergoing elective surgery.

Conclusion: A hypercoagulable state may be present in unstable as well as in stable angina pectoris patients accepted for coronary artery bypass surgery.