With the increasing use of OPCAB, potentially devastating thromboembolic events, including graft thrombosis may become increasingly evident. We present a study of the quantitative and temporal differences of the coagulation system, fibrinolysis and platelet activation after coronary artery surgery with or without cardiopulmonary bypass.

Patients undergoing on-pump CABG (n=10) or OPCAB (n=10) had six blood samples taken before surgery and up to 24h post-operatively. Activation of the coagulation cascade (tissue factor pathway—factor VIIa), endothelial injury (von Willebrand Factor antigen), thrombin generation (prothrombin fragments FI+II), fibrinolysis (decreased plasminogen levels), fibrin degradation (D-Dimer), platelet counts and platelet activation (soluble P-selectin) were quantified.

CABG caused earlier and more significant generation of thrombin, however OPCAB caused a late and sustained generation of thrombin. CABG caused intraoperative activation of fibrinolysis and fibrin degradation, however, at 24h these parameters were equally elevated in both groups. Platelet activation was significant in the CABG group, but did not occur in the OPCAB group.

Late thrombin generation and reduced fibrinolysis in the presence of intact, functioning platelets may contribute to adverse thromboembolic events after OPCAB surgery. Thromboembolic prophylaxis and anti-platelet therapy may need to be more aggressive after OPCAB surgery.