Editors:Mohammad Shenasa, MD Attending Physician, Department of Cardiovascular Services, O’Conner Hospital; Heart & Rhythm Medical Group, San Jose, California Mark E. Josephson, MD Director, Harvard-Thorndike Electrophysiology Institute and Arrhythmia Service; Chief Emeritus, Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center; Herman C. Dana Professor of Medicine, Harvard Medical School, Boston, Massachusetts N. A. Mark Estes III, MD Professor of Medicine, Tufts University School of Medicine; Director, New England Cardiac Arrhythmia Center, Tufts Medical Center, Boston, Massachusetts Ezra A. Amsterdam, MD Distinguished Professor, Associate Chief (academic affairs), Division of Cardiovascular Medicine, University of California, Davis, Medical Center, Sacramento, California Melvin Scheinman, MD Professor of Medicine, Walter H. Shorenstein Endowed Chair in Cardiology; Chief of Cardiology Genetics Arrhythmia Program, University of California, San Francisco, San Francisco, California