1 Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom. Electronic address: Stefan.Neubauer@cardiov.ox.ac.uk.
2 Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom; Royal Berkshire NHS Foundation Trust, Bristol, United Kingdom.