1 Cardiology Department, Royal Papworth Hospital, Cambridge (G.J.M., J.B.).
2 Department of Cardiology, University Medical Centre, Utrecht, the Netherlands (L.J.B., S.A.G., R.J.H.).
3 Department of Cardiology, Rigshospitalet, Copenhagen, Denmark (B.G.W., J.T.-H.).
4 Cardiovascular Clinical Academic Group, Molecular & Clinical Sciences Rsrch Inst, St. George's, University of London and St. George's University Hospitals NHS Foundation Trust, London, United Kingdom (B.E., C.S., E.R.B.).
5 Division of Cardiovascular Medicine, University of Cambridge, United Kingdom (J.B.).
6 Department of Cardiology, Cardiovascular Rsrch Inst Maastricht (CARIM) (B.v.R., P.G.V.A.), Maastricht University Medical Center, the Netherlands.
7 Department of Clinical Genetics (I.P.C.K.), Maastricht University Medical Center, the Netherlands.
8 Division of Cardiology, University of British Columbia, Vancouver, Canada (A.D.K.).