1. From the Center for Arrhythmia Prevention, Division of Preventive Medicine and Cardiovascular Division (C.M.A.) and Channing Laboratory (E.B.R., D.J.H.), Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Mass; Cardiovascular Research Center (E.G.N., C.A.M., P.T.E.) and Cardiology Division (C.A.M., P.T.E.), Massachusetts General Hospital, Boston, Mass; Department of Epidemiology, Harvard School of Public Health, Boston, Mass (D.J.H., E.B.R.); and Cardiovascular...