1. From the Center for Atrial Fibrillation, Section of Cardiac Pacing and Electrophysiology, Cleveland Clinic Foundation, OH (A.A.H., W.I.S., A.B., M.B., M.C.-P., R.A.-B., A.H., K.T., B.B., D.C., T.D., P.T., D.O.M., N.V., M.B., T.C., M.N., M.K., M.C., B.D.L., O.M.W.); and Texas CardiacArrhythmia Institute, St David’s Medical Center, Austin, TX (A.N.).