1. From the National Heart Lung and Blood Institute's and Boston University's Framingham Heart Study, Framingham, MA (E.J.B., D.D.M.); Cardiac Electrophysiology Section, Cardiovascular Medicine Division, Department of Medicine, University of Massachusetts Medical School, Worcester, MA (D.D.M.); Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA (D.D.M.); Department of Cardiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands ...