Abstract 4917: Clopidogrel Resistance and Coronary Artery Plaque Burden in Patients Undergoing Percutaneous Coronary Intervention
Background: Clopidogrel anti-inflammatory effect and plaque burden are important factors for atherothrombotic process. Data are lacking on relationship of plaque burden and clopidogrel resistance in patients undergoing percutaneous coronary intervention (PCI)
Methods: We identified 138 patients who had intravascular ultrasound during PCI between Jan 2007 to June 2007. Using the Verify Now Point-of-care assay, P2Y12 platelet reaction units (PRU) and percent inhibition of platelet activation (IPA) were measured 16 –24 hours after the loading dose of clopidogrel (600mg for patients not on clopidogrel daily, and 300mg for patients on clopidogrel 75mg daily) but before the next day of clopidogrel dose. CR was defined as PRU >200 or as IPA<10% or <20%.
Results: Mean age of patients was 66±11 years and 74% were males. PRU>200 was found in 53 patients (38.4%) and PRU ≤200 in 85 patients (61.6%). Presence of myocardial infarction, hyperlipidemia, renal disease, smoking history, stable or unstable angina at admission were similar between the PRU groups and between IPA groups. Hypertension, diabetes, older age and reference site plaque burden were higher in clopidogrel resistance (Table⇓). With use of alternative definitions, reference segment plaque burden was also higher in clopidogrel resistance patients: 0.50±0.12 vs 0.41±0.13 in <10% vs ≥10% platelet inhibition (p=0.05), and 0.49±0.12 vs 0.41±0.13 in <20% vs ≥20% platelet inhibition (p=0.03)
Conclusion: Clopidogrel resistance patients have more high risk baseline characteristics and higher plaque burden at the reference vessel segment, implying diffuse intracoronary atherosclerosis compared to clopidogrel sensitive patients who underwent PCI