Platelet FcRIIa Expression in Patients With Stable Coronary Artery Disease

Objectives. Fc gamma RIIa amplifies platelet activation and greater expression increases platelet reactivity. In patients with myocardial infarction (MI), high platelet Fc gamma RIIa identifies patients with an approximately 4-fold greater risk of MI, stroke, and death. We compared platelet Fc gamma RIIa in 2 groups: (1) patients who had not had an MI in the previous year and were undergoing cardiac catheterization and percutaneous coronary intervention (PCI) labeled as stable coronary artery disease (CAD), and (2) previously obtained results in patients with MI (n = 197). Methods. Patients undergoing cardiac catheterization and PCI were enrolled. Fc gamma RIIa expression was quantified with the use of flow cytometry. Comparisons were made with Mann-Whitney Rank Sum Test and Chi Squared analysis. Significance was defined as P < .05. Results. Compared to patients with MI, patients with stable CAD (n = 49) were older (70 +/- 9 years vs 63 +/- 12 years) and were more likely to have had prior MI (43% vs 23%), prior revascularization (62% vs 33%), diabetes (35% vs 24%), and hypertension (98% vs 66%). In patients with stable CAD, platelet Fc gamma RIIa was, on average, lower than that seen in patients with acute MI (9746 +/- 4316 vs 11 479 +/- 2405 molecules/platelet, P < .001). Patients with stable CAD exhibited a range of platelet Fc gamma RIIa (similar to 4500 to similar to 27 000 molecules/platelet) similar to that seen in acute MI patients (similar to 6500 to similar to 30 000 molecules/platelet). Conclusions. Compared to patients with MI, patients with stable CAD had, on average, lower platelet Fc gamma RIIa. However, the range of platelet Fc gamma RIIa was similar to that seen in patients with MI. These results support future studies designed to assess the prognostic implications of platelet Fc gamma RIIa in patients with stable CAD.