Evaluating Additional Platelet Inhibition in Patients With High Platelet Reactivity Undergoing Percutaneous Coronary Intervention

Patients admitted to hospital with chest pain due to reduced blood flow to heart muscle (diagnosis Acute Coronary Syndrome) can be treated with medication and an angioplasty ± stent procedure, which restores blood flow to the heart. Antiplatelet drugs (Aspirin and Clopidogrel) are blood thinning treatments and research has reported they reduce heart attacks, death and stroke. The investigators know some patients do not respond fully to Clopidogrel but currently patients are not tested for this. The investigators wish to perform a trial to identify those patients who do not respond fully to Clopidogrel and randomise them to either Prasugrel (newer drug) or a higher dose of Clopidogrel. Patients admitted to the hospitals (2 in the UK and 1 in Germany) will be asked for their consent to participate. A blood sample is tested for platelet activity. 1. Low platelet activity result means patient has responded well to Clopidogrel and will continue on the routine dose. They will be entered into an observational registry. Data will be collected of routine blood tests and investigations, medication and procedures. Their GP will be contacted at about 30 days to see if they are alive. 2. High platelet activity results means patient has not responded fully to Clopidogrel. These patients will be randomly allocated to a higher dose of Clopidogrel or new drug Prasugrel. Data will be collected of routine blood tests and investigations, medication and procedures. A hospital visit at 30±5 days is required to assess how patients are doing, medications and occurrence of any events.