1. From the Section of Cardiac Electrophysiology, Cardiovascular Institute, Warren Alpert Medical School of Brown University, Providence, RI (B.P.); Section of Cardiac Electrophysiology, Johns Hopkins Medical Institutes, Baltimore, MD (S.M., C.A.J., A.S.J.M.t.R., B.M., C.T., A.B., S.N., D.P.J., H.C., H.T., A.C.); and Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.J.M.t.R.).