Nirmal Ghati, Rajiv Narang, Hara Prasad Pati, Ashwani Kumar Mishra, Aseem Basha
OBJECTIVE: The effect of aspirin and clopidogrel is not uniform in all patients due to drug resistance. The study was designed to evaluate the prevalence of aspirin and clopidogrel resistance and its association with various risk factors in stable CAD patients. METHODS: Total 151 clinically stable CAD patients taking either aspirin and/or clopidogrel were recruited in this prospective cohort study. Platelet function testing was performed using light transmittance platelet aggregometry. All the patients were prospectively followed up to detect any MACE (death, non-fatal MI, stroke, revascularization), worsening angina and bleeding from any site. RESULTS: Total 11 (7.28%) patients showed complete resistance to aspirin, and an additional 35 (23.18%) patients showed semi-resistance. For clopidogrel, 44 (29.2%) and 11 (7.6%) patients had complete and semi-resistance, respectively. The prevalence of dual antiplatelet resistance was 7.6%. In univariate regression analysis, diabetes mellitus [OR 2.2 (95%CI 1.1-4.4); p=0.03] and clopidogrel resistance [OR 20.2 (8-50.7); p<0.01] showed significant association with aspirin resistance. The parameters significantly associated with clopidogrel resistance were - hemoglobin level [OR 0.8 (0.7-1); p=0.03], erythrocyte sedimentation rate [OR 1 (1-1.1); p=0.04], family history of CAD [OR 5.1 (1.5-17.1); p=0.01] and aspirin resistance [OR 20.2 (8.0-50.7); p<0.01]. In multivariable analysis, apart from the significant association between aspirin and clopidogrel resistance, family history of CAD was the only independent predictor of clopidogrel resistance. The study was underpowered to detect any meaningful effect on MACE due to low event rate. CONCLUSION: In our study high prevalence of aspirin and clopidogrel resistance was detected. Although aspirin and clopidogrel resistance showed significant association with clinical risk factors, their association with MACE was inconclusive.