1 Department of Cardiovascular Sciences, British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine, Faculty of Life Sciences and Medicine, King's College London, The James Black Centre, 125 Coldharbour Lane, London SE5 9NU, UK.
2 Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties, Cardiology Unit, University of Palermo, University Hospital P. Giaccone, Palermo, Italy.
3 Cardiology Department, King's College Hospital NHS Foundation Trust, London, UK.