1. Cardiology Department, St Bartholomew's Hospital, Barts Heart Centre, West Smithfield, London EC1A 7BE, UK
2. Department of Cardiac Surgery, Brighton and Sussex Medical School, 94 N - S Rd, Falmer, Brighton BN1 9PX, UK
3. Cardiology Department, East Sussex Healthcare NHS Trust, Kings Drive, Eastbourne, East Sussex BN21 2UD, UK