Uniform platelet activation exists before coronary stent implantation despite aspirin therapy

Background Platelets play an important role in the natural history of coronary artery disease. Enhanced platelet aggregation and receptor expression unquestionably occur after coronary stent implantation; however, the functional characteristics of platelets before stenting have not been fully elucidated. Methods Platelets were assessed before intervention by platelet-rich plasma aggregation (PA) with 5 mu mol adenosine diphosphate (ADP) and I mug/mL collagen; whole blood aggregation (WBA) by 1 mug/mL collagen; shear-induced closure time (CT); contractile force (CF); and expression of 9 surface receptors by flow cytometry in 126 patients undergoing elective coronary artery stent placement. All patients received aspirin for at least 7 days. The data were compared with those from 64 healthy volunteers. Results Each test revealed sustained platelet activation in patients undergoing coronary stenting compared with control values. These differences were significant for collagen-induced PA (P = .031); CF (P = .0001); expression of glycoprotein (GP) IIb/IIIa (P = .0001); P-selectin (P = .0008); platelet/endothelial cell adhesion molecule (PECAM)-1 (P = .0001); CD107a (P = .0001); CD107b (P = .0004); and CD63 (P = .009). Conclusion Platelets are indeed activated before coronary stenting despite antecedent therapy with aspirin.