1. From the Department of Cardiology (A.C.L., R.J.J., R.K., T.M.S., P.S., M.R., A.D., C.D.M., S.W.D.), Department of Cardiovascular Magnetic Resonance (F.A., D.J.P., R.H.M.), and Department of Surgery (N.E.M.), Royal Brompton and Harefield NHS Trust, London, United Kingdom; Department of Statistics, London School of Hygiene and Tropical Medicine, University College London, United Kingdom (K.H.); and Department of Cardiovascular Medicine, Imperial College, London, United Kingdom (D.J.P., R.H.M.).