1. Department of Medicine, Faculty of Medicine, Imperial College London, London, UK
2. Department of Cardiothoracic Surgery, Imperial College NHS Trust, Hammersmith Hospital, London, UK
3. Department of Surgery and Cancer, Imperial College London, London, UK
4. Department of Surgery, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
5. Department of Cardiothoracic Surgery, James Cook University Hospital, Middlesborough, UK