1. Toronto Congenital Cardiac Centre for Adults, Peter Munk Cardiac Centre, University Health Network, University of Toronto, Ontario, Canada (W.M.W., E.J.H., S.L.R., C.K.S., R.M.W.).
2. Adult Congenital Heart Disease Program, Royal Melbourne Hospital, University of Melbourne, Victoria, Australia (W.M.W., L.E.G., E.T.).
3. Children’s Hospital Boston, Harvard Medical School, MA (A.M.V., M.G., K.H., J.E.M.).
4. Queen Elizabeth Hospital, University Hospitals Birmingham, United Kingdom (P.C., Y.E.).
5. Adult Congenital Heart Disease Program, Knight Cardiovascular Institute, Oregon Health Science University, Portland (L.B.).
6. Northern Alberta Adult Congenital Heart Program, University of Alberta, Edmonton, Canada (P.G., I.V.M.).
7. Pacific Adult Congenital Heart Clinic, Division of Cardiology, St Paul’s Hospital, University of British Columbia, Vancouver, Canada (J.G.).
8. University Heart Centre, University Hospital Zurich, Switzerland (M.G.).
9. Montréal Heart Institute Adult Congenital Center, Université de Montréal, Quebec, Canada (P.K.).