Platelet reactivity characterized prospectively - A determinant of outcome90 days after percutaneous coronary intervention

Background-Platelet activation is pivotal in the pathogenesis of complicati ons after percutaneous coronary interventions (PCI). We previously reported substantial interindividual variability in activation of glycoprotein (GP) IIb/IIIa in response to a low concentration of ADP. We assessed GP IIb/III a activation prospectively to determine whether this could differentiate pa tients at low risk from those at high risk for complications early and late after PCI. Methods and Results-A total of 112 patients undergoing PCI were studied. Pl atelet reactivity was determined with the use of flow cytometry, Patients w ere classified into high and low platelet reactivity groups on the basis of extent of activation of GP IIb/IIIa in response to 0.2 mu mol/L ADP. The m edian value was used for differentiation. The incidence during 90-day follo w-up interval of a composite end point (myocardial infarction, urgent revas cularization, or repeat revascularization) was determined in each group. Fo llow up was completed in all 112 patients. The 2 groups were similar with r espect to diverse clinical characteristics. Nevertheless, the incidence of the composite end point occurred in 26.8% of the high and 7.1% in the low p latelet reactivity group (P=0.01). The difference in the composite end poin t was most striking during the 30- to 90-day interval after PCI (16.7% vers us 1.9%; P=0.02). Repeat revascularization was more frequent in those with increased platelet reactivity (17.9% versus with 3.6%, P=0.029). Conclusions-Prospective assessment of platelet GP IIb/IIIa activation permi ts stratification of patients into low- and high-risk groups with respect t o adverse events after PCI.