Reduced platelet activity is associated with early clot growth and worse 3-month outcome after intracerebral hemorrhage

Background and Purpose-Antiplatelet medication use and reduced platelet activity may be associated with mortality after intracerebral hemorrhage (ICH). We tested the hypothesis that reduced platelet activity is associated with early ICH clot growth and worse outcomes. Methods-We prospectively identified patients with spontaneous ICH, measured platelet activity (VerifyNow-ASA, Accumetrics) on admission, and recorded antiplatelet medication use. ICH volume was calculated using computerized volumetric analysis. Data were analyzed with nonparametric statistics and repeated measures ANOVA as appropriate. Patients were prospectively followed for functional outcomes. Data are presented as mean±SD or median [Q1 to Q3]. Results-Reduced platelet activity (≤550 aspirin reaction units [ARU]) was associated with increased ICH volume growth (P<0.05) for patients with the diagnostic CT within 12 hours. In the subset of patients not known to take aspirin, 24% had reduced platelet activity. Sixteen (24%) patients received a platelet transfusion 21.2±11.4 hours after symptom onset with an increase in platelet activity (448 [414-479] to 586 [530-639] ARU, P=0.001), but without impact on outcomes. Reduced platelet activity was associated with worse modified Rankin Scores at 3 months (P=0.02). Conclusions-Reduced platelet activity was associated with early ICH volume growth and worse functional outcome. Because platelet activity can be increased with platelet transfusion, increasing platelet activity is a potential method to reduce ICH volume growth and improve functional outcomes.