Prasugrel Versus Clopidogrel in Acute Coronary Syndrome (ACS) Undergoing Percutaneous Coronary Intervention (PCI)

Background: Both prasugrel and clopidogrel are prescribed drugs which compete as platelet inhibitors in patients with acute coronary syndrome (ACS). Whether rates of drug resistance/hyporesponsiveness are lower with prasugrel and whether more consistent and earlier onset of platelet inhibition may reduce infarct size in patients with ACS undergoing early PCI remains, at present, unknown. Study design/study population: This trial is a prospective, open-label, single centre observational trial. Patients receive either prasugrel (60mg) or clopidogrel (600mg) at the discretion of the attending cardiologist. Patients with exclusion criteria for prasugrel will be excluded for clopidogrel as well. The study population includes 80 subjects with moderate to high-risk ACS, ie patients with unstable angina (UA) and non-ST-segment elevation MI (NSTEMI) and TIMI risk score of 3 or higher, within 72 hours after onset of symptoms. In all patients early PCI is planned. Study objective/endpoint/methods: The primary objective of this trial is to evaluate whether rates of hyporesponsiveness are lower with prasugrel and whether more consistent and earlier onset of platelet inhibition may reduce infarct size in ACS in patients undergoing early PCI. The primary endpoint is the rate of drug resistance at time of index intervention. Optical and impedance aggregometry using ADP (5 and 20 μM) and collagen (1 μg/ml) as platelet agonists is used to measure platelet aggregation. Addition of the specific antagonists aspirin and mesamp to the probe is used to discriminate between pharmacodynamic and pharmacokinetic drug resistance. Secondary endpoint is the reduction of myocardial infarct size determined by post-interventional increase of high sensitive TnT (TnT hs) during the days following the index event reflecting earlier, more effective and more consistent inhibition of platelet function. Tertiary endpoint is the composite clinical endpoint of cardiovascular death, nonfatal MI, or strok