We will recruit patients being referred for cardiac MRI scanning for clinical reasons as well as inviting patients to volunteer for an MRI. Patients who do not require a cardiac MRI for clinical reasons will be over the age of 8 years to allow for cooperation with the MRI without general anaesthesia. Patients under follow up by the heart failure team will be contacted by their primary care consultant in the first instance to introduce the study and invite the patient to participate. It will be made clear there is no obligation to join the study and their treatment will be unaffected by their decision. They will be free to withdraw consent at any time. The patients will be invited to phone the study coordinator (DP) to ask questions, express willingness to participate or to decline. Non-responders will be sent one further letter of invitation.