Abstract 4487: Clopidogrel Resistance in Patients Undergoing Percutaneous Coronary Intervention: One Year Outcome

Background: Clopidogrel therapy is critical in patients undergoing percutaneous coronary intervention (PCI). Data are lacking on long term outcomes of clopidogrel resistance (CR) and its definition. Methods: We identified 389 patients who underwent PCI during a 6 month period. Using the VerifyNow 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 clopidogrel dose. CR was defined as PRU >200, %IPA<10% or IPA<20%. Major adverse cardiac events (MACE) included death, myocardial infarction, coronary artery bypass graft surgery and unplanned repeat coronary revascularization. Results: Mean age of patients was 65±11 years, 24% females and 31% diabetics. PRU mean value is 173±93, IPA mean value=47.5±42, CR is found in PRU>200 =36%(140), IPA<10% =8%(31), IPA <20% = 16.4%(64) patients. Presence of myocardial infarction, hypertension, hyperlipidemia, renal disease, smoking history, stable or unstable angina at admission were similar between the PRU groups and between IPA groups. Diabetes and older age were more prevalent in clopidogrel resistance patients. 1-year MACE rates are shown below. Conclusion: Clopidogrel resistance is an important predictor of long-term MACE in patients undergoing PCI, particularly when defined as Platelet Reaction Units >200.