Time course of platelet activation following acute ischemic stroke

To assess the time course of platelet activation after acute ischemic stroke we measured the platelet protein ß-thromboglobulin (BTG) in 66 patients. Serial samples were obtained over a 3-month period. Mean values of BTG in patients with lacunar infarction were not significantly elevated at any time. In nonlacunar strokes, the mean BTG level during the first week after stroke was not significantly elevated. The mean BTG level rose in the second week and became statistically different from control (mean ± SEM; 33.1 ± 3.6 vs. 21.3 ± 2.0 IU/ml, p = 0.01). Mean values then declined to normal. Significant differences were noted among stroke subtypes. During the first week, mean values of BTG were higher in cardioembolic stroke (36.9 ± 6.2 IU/ml, p = 0.007 vs. controls) than in atherothrombotic stroke (22.1 ± 2.8 IU/ml, p = 0.82). By the second week, mean BTG values were significantly elevated for both cardioembolic (44.4 ± 8.3 IU/ml, p < 0.001) and atherothrombotic (33.8 ± 5.0 IU/ml, p = 0.01) strokes. The rise of this marker following stroke suggests that at least some of the platelet activation associated with stroke is a secondary phenomenon. Cardioembolic stroke is associated with as much platelet activation as atherothrombotic stroke and may have greater platelet activation during the first week after stroke.