1. From the Department of Cardiology, Papworth Hospital, Papworth Everard (S.P.H., P.M.H., S.N.K., R.D., C.G.D., S.C.C., L.M.S., P.M.S., M.O.); Department of Cardiovascular Medicine, Addenbrooke’s Hospital (S.P.H., P.M.H., S.N.K., L.M.S., P.M.S., M.O., D.P.D.); and MRC Biostatistics Unit, Robinson Way (L.S.), Cambridge, UK.