1. From the Texas Cardiac Arrhythmia Institute, St. David’s Medical Center, Austin (S.M., P.M., C.T., C.G., D.G.D.R., L.D.B., A.N.); Dell Medical School, Austin, TX (S.M., A.N.); Electrophysiology and Arrhythmia Services, California Pacific Medical Center, San Francisco (A.N.); MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH (A.N.); and Division of Cardiology, Stanford University, CA (A.N.).