Comparison of early platelet activation in patients undergoing on-pump versus off-pump coronary artery bypass surgery

Objective: Cardiopulmonary bypass has been shown to be associated with platelet dysfunction, which has a potential for increasing the risk of perioperative bleeding. Off-pump coronary artery bypass surgery is thought to avoid this deleterious effect of pump use on platelets. However, the influence of off-pump coronary artery bypass surgery on platelets has not been thoroughly studied. Methods: Accordingly, we evaluated 60 patients undergoing coronary artery bypass grafting prospectively using cardiopulmonary bypass and warm cardioplegic arrest (n = 30) or an off-pump technique (n = 30). Platelet function was evaluated before and 2 hours after coronary artery bypass grafting. Results: Among patients undergoing on-pump coronary artery bypass surgery, all studies of platelet function were significantly abnormal after surgical intervention compared with results before surgical intervention. Similarly, among patients undergoing off-pump coronary artery bypass surgery, evidence of platelet dysfunction after surgical intervention was noted, with a lower platelet count and a higher proportion of P-selectin- and Annexin V-positive platelets. However, compared with the preprocedural value, the postprocedural decrease in platelet count (78,200 x 10(3)/mu L vs 103,000 x 10(3)/mu L) and platelet aggregation (0.8% vs 10.9%) and increase in bleeding time (0 minutes vs + 1.3 minutes), P-selectin-positive platelets (6.0% vs 9.1%), and Annexin V-positive platelets (1.7% vs 3.7%) were significantly lower in the off-pump coronary artery bypass surgery group compared with those in the on-pump coronary artery bypass surgery group, respectively. Conclusions: Early postoperative decrease in platelet count and increase in platelet activation occurs to a much lesser extent and does not alter bleeding time or adenosine diphosphate-induced platelet aggregation in patients undergoing off-pump coronary artery bypass surgery. This lack of significant effects on platelets might in part account for the potential decreased risk in bleeding and for the preserved hemostasis seen in patients undergoing off-pump coronary artery bypass surgery compared with those undergoing on-pump coronary artery bypass grafting surgery.