1. Cardiology, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London W12 0HS, UK
2. Department of Cardiology, Heart Center Cologne, Faculty of Medicine, University Hospital, University of Cologne, 50937 Cologne, Germany
3. Cardiac Catheterisation Laboratory, Cardiothoracic and Vascular Department, Azienda Ospedaliero Universitaria Pisana, 56126 Pisa, Italy
4. Università di Pisa, Lungarno Pacinotti 43, 56126 Pisa, Italy
5. Department of Cardiology, Essex Cardiothoracic Centre, Mid and South Essex NHS Foundation Trust, Basildon SS16 5NL, UK
6. Cardiology, Royal Berkshire Hospital, Reading RG1 5AN, UK