1. National Heart and Lung Institute, Imperial College London , Du Cane Road, London W12 0NN , UK
2. Department of Cardiology, Hammersmith Hospital, Imperial College Healthcare NHS Trust , Du Cane Road, London W12 0NN , UK
3. Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School , 330 Brookline Avenue, Boston, MA 02215 , USA
4. Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School , 330 Brookline Avenue, Boston, MA 02215 , USA
5. Department of Electrical and Electronic Engineering, Imperial College London , South Kensington Campus, Exhibition Road, London SW7 2AZ , UK