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 mu mol/L adenosine diphosphate. Clopidogrel nonresponse was defined as a mean platelet aggregation >= 40% with 5 mu mol/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) and 35% (n=54) were nonresponders to aspirin and clopidogrel, respectively. After platelet function testing, antiplatelet therapy was increased in 23% of patients (n=73). After propensity score matching (n=61 in each group), antiplatelet therapy modification was associated with significantly increased rates of death, ischemic events, or bleeding (hazard ratio, 2.24; 95% CI, 1.12-4.47; P=0.02) compared with no modification in antiplatelet therapy and a trend toward increased bleeding (hazard ratio, 3.56; 95% CI, 0.98-12.95; P=0.05). No differences in ischemic events were observed. Conclusions-Platelet function-guided modification in antiplatelet therapy after an ischemic stroke or transient ischemic attack was associated with significantly higher rates of adverse clinical outcomes. (Stroke. 2012;43:2376-2381.)