Despite recent improvements in treatment, myocardial infarction (heart attack) is still a leading cause of illness and death in the UK. Following the acute event, it is difficult to predict which patients are at risk of further problems, such as heart failure and is therefore difficult to know which patients need more aggressive/intensive treatment and monitoring.

There needs to be a test which is safe, reliable and reproducible that can be used shortly after a heart attack to both predict future cardiac events and to allow the efficacy of new treatments to be assessed.

Myocardial oedema (swelling of the heart muscle) has been demonstrated using Cardiac Magnetic Resonance (CMR), to occur following a heart attack and has been suggested as a marker for future cardiac events. The optimum time to perform this scan, the method of data analysis and it's effectiveness as a predictor of future cardiac events has not been adequately assessed.

This trial will assess the amount and natural time-course of oedema in the first 10 days following a heart attack. It will also correlate the amount of oedema with the size of scar (damaged heart muscle) and left ventricular ejection fraction (heart function) at 3 months to assess if it is a predictive marker.

Inclusion Criteria:

1. Patients presenting to the London Chest Hospital with acute ST elevation myocardial infarction and treated with primary angioplasty and stent implantation within 12 hours of symptom onset
2. Acute PCI / stent implantation has been successful (residual stenosis visually < 30% and TIMI flow ≥ 2)
3. At the time of inclusion, the patient no longer requires intravenous catecholamines or mechanical hemodynamic support (aortic balloon pump)
4. Serum troponin >1ng/ml 12 hours after onset of pain
5. The patient is able to give written informed consent
6. The patient must be able to understand and communicate in English

Exclusion Criteria:

1. Known cardiomyopathy
2. Previous documented myocardial infarction
3. Previous percutaneous coronary intervention or coronary artery bypass surgery
4. Significant renal dysfunction (EGFR<30)
5. Systemic steroid therapy
6. Current non steroidal anti-inflammatory drug use
7. Chronic inflammatory disease
8. Neoplastic disease without documented remission within the past 5 years
9. Pregnancy
10. Reduced mental capacity leading to inability to obtain informed consent
11. Participation in another clinical trial within the last 30 days

Patients admitted to The London Chest Hospital following an ST elevation myocardial infarction who have been successfully treated with primary angioplasty.