Prevalence of clopidogrel nonresponder in patients with coronary artery disease

Abstract

Introduction : The current guidelines recommend dual antiplatelet of aspirin and clopidogrel for patients who have acute coronary syndrome (ACS) or those undergoing percutaneous coronary intervention (PCI).

Objective : To determine the frequency of clopidogrel nonresponder in patients with coronary artery disease (CAD).

Setting : Division of Cardiology, Phramongkutklao Hospital.

Research design : A prospective study.

Patients : All consecutive patients with angiographic diagnosis of CAD were recruited. The study consisted of patients who had taken clopidogrel 75 mg/day for at least 5 days and those who received loading dose of clopidogrel 300 mg and aspirin 300 - 325 mg before undergoing PCI. All patients were treated with aspirin 81 - 325 mg/day at least 7 days prior to the study. Exclusion criteria included previous treatment with proton pump inhibitors (PPIs) within 2 weeks and serum creatinine >1.5 mg/dl.

Methods : The effect of clopidogrel on platelet aggregation was measured by light transmission aggregometry using ADP 20 /dM as the agonist. Clopidogrel nonresponder was defined as ADP 20 /dM-induced maximal platelet aggregation (MPA) > 50%.

Results : There were 85 patients enrolled during August 2008 to January 2009. Overall, 19% were scheduled for elective PCI patients and 81% were stable CAD. I/Ve found that 34% of the patients were clopidogrel nonresponders. Average value of MPA after ADP 20 /dM stimuli was 38.57 ± 20.25%.

Conclusion : Our study has found the prevalence of clopidogrel nonresponder, 34%, as tested by ADP 20 fdM-induced maximal platelet aggregation in CAD patients.