Relationship between aspirin and clopidogrel responses in acute coronary syndrome and clinical predictors of non response.

OBJECTIVES: We have prospectively investigated the association between aspirin and clopidogrel responses and the clinical predictors of non response. METHODS: 635 Non ST Elevation Acute Coronary Syndrome (NSTE ACS) patients were included and received loading doses of 250 mg aspirin and 600 mg clopidogrel. We analyzed post-treatment maximal intensity of arachidonic acid and ADP-induced platelet aggregation (AA-Ag and ADP-Ag) and Platelet Reactivity Index of VAsodilator-Stimulated Phosphoprotein (PRI VASP). Aspirin and clopidogrel non responses were defined respectively by AA-Ag>30% and ADP-Ag>70%. RESULTS: Aspirin non responders patients had significantly higher ADP-Ag and PRI VASP than aspirin responders: 63.7+/-15.9% vs 55+/-19% (p=0.0001) and 73.6+/-13.3% vs 53+/-23% (p=0.0001) respectively and the rate of clopidogrel non responders was higher among aspirin non responders than aspirin responders: 36.7% vs 22.7% (p=0.003). In addition, clopidogrel non responders had significantly higher AA-Ag and rate of aspirin non responders than clopidogrel responders: 21.6+/-24% vs 10.3+/-19% (p=0.0001) and 22.8% vs 12.9% (p=0.003) respectively. Age and Body Mass Index (BMI) were significantly associated with non response to Clopidogrel (p=0.035 and 0.02 respectively) and diabetes mellitus by trend (p=0.07). CONCLUSION: We observed a relationship between aspirin and clopidogrel non responses and an association between age, BMI and diabetes mellitus and clopidogrel response.