1. From Department of Cardiology, Children’s Hospital Boston, Harvard Medical School, MA (V.B.L., M.G.); Department of Pediatrics, Montreal Children’s Hospital, McGill University, QC, Canada (V.B.L.); Cardiovascular Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (P.R.L.); Department of Medicine, McGill University Health Center, Montreal, QC, Canada (P.R.L., L.P.); and Division of Cardiology, Jewish General Hospital (M.J.E.) and McGill Adult Unit for Congenital Heart Disease...