1. From the National Institute for Health Research Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, National Heart and Lung Institute, Imperial College London, London, United Kingdom (A.S.J., C.S.B., R.R., G.-P.D., W.L., K.D., J.S.W., D.J.P., M.A.G., S.V.B.-N.); Department of Cardiology, Rigshospitalet, Copenhagen, Denmark (A.S.J.); Adult Congenital Heart Program, Knight Cardiovascular Institute, Oregon Health and Science University Portland (C.S.B.); Section...