Collagen-Induced Platelet Aggregates, Diabetes, and Aspirin Therapy Predict Clinical Outcomes in Acute Ischemic Stroke.

Background: Aggregation of platelets is a trigger for additional development of larger thrombi. This study aimed to identify factors that may affect platelet aggregability and their role in clinical outcomes in acute ischemic stroke. Methods: Consecutive acute ischemic stroke patients (n = 352) who were transferred within 24 hours after its onset were enrolled. Peripheral venous blood was sampled to measure platelet aggregability and other parameters. Results: Mean values of spontaneous small-sized platelet aggregates and collagen- or adenosine diphosphate (ADP)-induced large-sized aggregates were elevated in acute ischemic stroke. In atherothrombotic stroke (n = 178), collagen and ADP-induced large-sized aggregates were positively correlated with HbA1c, respectively. High incidence of the modified Rankin Scales (mRS) 5-6 at discharge was associated with diabetes complication (odds ratio [OR] 8.77, 95% confidence interval [CI] 1.32-57.56). The proportion of patients who were functionally independent (the mRS 0-2) at discharge was lower in the middle tertile of collagen and ADP-induced large-sized aggregates than their low tertile (OR 2.46, 95% CI 1.09-5.58; OR 2.43, 95% CI 1.05-5.59, respectively). Prestroke administration of aspirin recovered the proportion of independence at discharge (OR 0.25, 95% CI 0.06-0.99), and ameliorated incidence of the mRS 5-6. On logistic regression analysis, diabetes, HbA1c, collagen-induced large-sized aggregates, and prestroke administration of aspirin remained independent predictors of clinical outcomes in atherothrombotic stroke. In cardioembolic and lacunar stroke, no relations with clinical outcomes were found. Conclusions: High plasma level of HbA1c is involved in enhanced platelet aggregability in acute atherothrombotic stroke patients, and prestroke administration of aspirin may be beneficial to clinical outcomes.