1. Department of Cardiology, University Hospital of Wales, Cardiff, United Kingdom (T.K., S.G., V.F., M.P., L.B., P.D., R.A., A.S.).
2. Keele Cardiovascular Research Group, Institute of Applied Clinical Sciences, University of Keele, Stoke-on-Trent, United Kingdom (T.K., M.A.M.).
3. Institute of Cardiovascular Sciences, Birmingham University, United Kingdom (P.L.).
4. Division of Statistics, Biosensors SA, Morges, Switzerland (S.C.).
5. Department of Cardiology, Royal Stoke Hospital, UHNM, Stoke-on-Trent, United Kingdom (M.A.M.).
6. Department of Cardiology, University Hospital NHS Trust, Southampton, United Kingdom (N.C.).