Detecting scarred heart muscle is important to diagnose and treat of a wide variety of heart conditions. Magnetic resonance imaging (MRI) can assess scarred heart muscle but it is time consuming, contraindicated for some patients and not tolerated by others. Computed tomography (CT) imaging has the potential to provide a rapid comprehensive assessment of the heart. This study will assess CT imaging of the heart muscle of patients who have previously undergone MRI of their heart. Using a state of the art CT scanner the investigators will develop a low radiation dose protocol to identify scarred heart muscle. The investigators will use and develop software techniques to analyse these images. This will enable us to develop a new way to identify and measure scarred heart muscle that will benefit patients with heart disease.

Inclusion Criteria:

• Presence of late enhancement on magnetic resonance imaging

Exclusion Criteria:

• age less than 40
• inability or unwillingness to undergo CT
• renal failure (serum creatinine >200 umol/l or estimated glomerular filtration rate <30 ml/min)
• hepatic failure
• allergy to iodinated contrast
• pregnancy
• breast feeding
• inability to undergo informed consent
• fast atrial fibrillation

Patients who have previously undergone magnetic resonance imaging which showed myocardial late enhancement.