CMR will be performed in the Robert Steiner MR Unit/Imaging Department, Hammersmith Hospital using a 1.5 tesla scanner according to standard protocols. Each scan will last about 1h and information will be collected on tissue characteristics, left ventricular function, wall motion abnormalities, myocardial perfusion. Myocardial infarcts will be detected by late contrast gadolinium enhancement. Gadolinium will be used at doses up to 0.2mmol/kg and is safe with an incidence of mild and transient side effects including headache and nausea of ~1%. Scans will be performed with under continuous ECG monitoring with a doctor and at least 1 other person present. Resuscitation facilities will be available at all times and the MRI facility is covered by an experienced 24 hour a day cardiac arrest team.