1. From the Center for Arrhythmia Care, University of Chicago Medicine, IL (M.N.B., C.E.S., R.T., G.A.U.); University Hospitals Cleveland Medical Center, OH (A.L.W.); Leiden University Medical Center, The Netherlands (C.J.W.B.); The Mayo Clinic, Rochester, MN (D.L.H.); and Massachusetts General Hospital, Boston (J.P.S.).