PCI and clopidogrel: antiplatelet responsiveness and patient characteristics

Objective 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 75 mg daily were monitored with the PEA 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. Conclusion 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.