1. From the Department of Medicine, QEII Health Sciences Centre, Halifax, NS, Canada (J.L.S., R.P., C.J.G.); Biosense Webster, Diamond Bar, CA (C.B., R.B.); Department of Medicine, University of Leiden Medical Center, Leiden, the Netherlands (K.Z.); Cardiac Sciences Department, Libin Cardiovascular Institute, Calgary, AB, Canada (V.K.); and Department of Medicine, Brigham and Women’s Hospital, Boston, MA (W.G.S.).