1. Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Pennsylvania Health System, Philadelphia (R.C.A., S.M., M.K., P.S., F.C.G., T.H., E.S.Z., F.E.M.).
2. Department of Cardiology, Hôpital Erasme, Université Libre de Bruxelles, Belgium (R.C.A.)
3. Department of Cardiology, Centre Hospitalier Princesse Grace, La Colle, Monaco (D.G.L., B.E., M.E., N.S.).