P612Modifiers of antiplatelet responsiveness

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This study on responsiveness to clopidogrel and aspirin evaluates its interaction with: (i) patient characteristics; (ii) procedure characteristics; (iii) antiplatelet dose.

Methods and results

After elective PCI, 60 patients receiving aspirin 100 mg daily, and clopidogrel 75mg daily were monitored with the PFA 100 test and VASP assay. Non-responsiveness to aspirin and clopidogrel was found in 23 (38%) and 18 (30%) of 60 patients, respectively. Seven (12%) patients were dual non-responders. Non-responders to both aspirin and clopidogrel were more often smokers. Non-responders to clopidogrel, in addition had elevated inflammatory markers (p < 0.05). Dual non-responders had (i) a higher platelet count, LDL, and CRP; (ii) a lower HDL (p < 0.05). Clopidogrel non-responders were receiving 150 mg clopidogrel, with a positive response in 72%. Eighty % of non-responders to 150 mg clopidogrel were also non-responders to aspirin.


Baseline patient characteristics and clopidogrel dose modify the antiplatelet response. Also, patients resistant to both aspirin and clopidogrel do no benefit from an increased clopidogrel dose.

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