1. From the Arrhythmia Unit (S.K., C.R.B., K.N., S.M., S.H.B., E.-K.C., L.M.E., B.A.K., R.M.J., G.F.M., W.G.S., U.B.T.), Interventional Cardiology and Vascular Medicine, Cardiovascular Division (P.S., A.C.E.), and Division of Cardiac Surgery (G.S.C.), Brigham and Women’s Hospital, Boston, MA.