Paul Morris MBChB MRCP BMedSciSpecialist Registrar in Cardiology, Sheffield Teaching Hospitals NHS, Foundation Trust, Clinical Research Fellow, University of Sheffield, Sheffield, UK David Warriner BSc MBChB MRCP DipSEMSpecialist Registrar in Cardiology, Sheffield Teaching Hospitals NHS, Foundation Trust, Sheffield, UK Allison Morton BMedSci MBChB PhD FRCPConsultant Cardiologist, Heartcare Western Australia, Bunbury, WA, Honorary Senior Lecturer, University of Sheffield, UK Paul Mayhew BScMedical Writer, Berlin, Germany