Clinical Outcomes Using a Platelet Function-Guided Approach for Secondary Prevention in Patients With Ischemic Stroke or Transient Ischemic Attack

Background and Purpose—Antiplatelet therapy nonresponse is associated with worse clinical outcomes. We studied the clinical outcomes associated with platelet function-guided modifications in antiplatelet therapy in patients with ischemic stroke or transient ischemic attack. Methods—From January 2005 to August 2007, 324 patients with ischemic stroke underwent platelet function testing using platelet aggregometry. Aspirin nonresponse was defined as a mean platelet aggregation ≥20% with 0.5 mg/mL arachidonic acid and/or ≥70% with 5 μmol/L adenosine diphosphate. Clopidogrel nonresponse was defined as a mean platelet aggregation ≥40% with 5 μmol/L adenosine diphosphate. A modification was any increase in antiplatelet therapy occurring after testing. Clinical outcomes were compared between patients with and without platelet function-guided antiplatelet therapy modifications using univariate and propensity score-adjusted analyses. Results—In patients with ischemic stroke or transient ischemic attack, 43% (n=128)...