Platelet FcγRIIa Expression in Ischemic Stroke: A Marker of Increased Platelet Reactivity

Background Platelet Fc gamma RIIa amplifies platelet activation and, thus, increased expression identifies patients with increased platelet reactivity. Previous work has demonstrated that platelet Fc gamma RIIa can identify patients at high and low risk of subsequent cardiovascular events after myocardial infarction (MI). This study was designed to compare platelet expression of Fc gamma RIIa in patients with stroke and transient ischemic attack (TIA) with that in patients with a recent MI.Methods Patients were enrolled based on an admitting diagnosis of stroke/TIA, and the discharge diagnosis was used to categorize patients into stroke/TIA (n=99) and other causes of neurologic dysfunction (hemorrhagic, trauma, toxic, and seizure; n=14). Patients with stroke/TIA were divided into embolic (both cardioembolic and thromboembolic; n=32) and not embolic causes (n=67). Results were compared with platelet Fc gamma RIIa expression in patients with recent MI from a previous study (n=197). Platelet expression of Fc gamma RIIa (molecules of Fc gamma RIIa/platelet) was quantified with the use of flow cytometry. Results are mean +/- SD.Results Platelet expression of Fc gamma RIIa was similar in patients with ischemic (both embolic and nonembolic) stroke/TIA (11 332 +/- 4127), embolic (11 204 +/- 3889) and nonembolic (11 393 +/- 4263) causes, and MI (11 479 +/- 2405). Patients with other causes of neurologic dysfunction had modestly but not significantly lower platelet expression of Fc gamma RIIa (9389 +/- 2883; P=0.13).Conclusions Platelet expression of Fc gamma RIIa was similar in patients with stroke/TIA and recent MI. These results support future studies designed to determine whether platelet Fc gamma RIIa expression can discriminate risk of subsequent stroke/TIA and its potential use as a precision tool capable of guiding individualized treatment decisions.