Following standard care angiogram / angioplasty, patient-participants will be given a minimum of 3 hours to consent to ensure that there is no delay in clinical treatment. A short information sheet will be given to the patient initially. If the patient is interested in the study, the full participant information sheet will be given. If potential patient-participants consent to study participation 3-5ml of blood will be venesected and sent for EPC analysis. That late evening atorvastatin 80mg will be given as per current national recommendations. Patient-participants will then have venesection for EPC analysis on days 1-2, 3-4 and finally 7-8. ACS patients are usually in hospital for 3 or 4 days provided there are no complications. It is therefore anticipated that days 0, 1-2 and 3-4 venesections may be performed whilst patient-participants are within the cardiology department. However an outpatient cardiology research clinic follow up will be arranged for day 7-8 to allow the final venesection for EPC analysis.