1 Cardiology and Aortic Centre, Royal Brompton & Harefield NHS Foundation Trust, London, United Kingdom; National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom. Electronic address: C.Nienaber@rbht.nhs.uk.
2 Department of Cardiac Surgery, Royal Brompton & Harefield NHS Foundation Trust, London, United Kingdom.
3 Cardiology and Aortic Centre, Royal Brompton & Harefield NHS Foundation Trust, London, United Kingdom; National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom.