1. National Heart, Lung, and Blood Institute’s and Boston University’s Framingham Heart Study, MA (L.S., H.L., D.L., E.J.B., L.T.).
2. Department of Cardiology, Copenhagen University Hospital Herlev and Gentofte, Helleup, Denmark (L.S.).
3. Department of Biostatistics (S.R.P., L.T.), Boston University School of Public Health, MA.
4. Section of Computational Biomedicine (H.L.), Department of Medicine, Boston University School of Medicine, MA.
5. Cardiac Arrhythmia Service and Cardiovascular Research Center, Massachusetts General Hospital, Boston (S.A.L., P.T.E.).
6. Department of Epidemiology (E.J.B.), Boston University School of Public Health, MA.
7. Cardiology and Preventive Medicine Sections (E.J.B.), Department of Medicine, Boston University School of Medicine, MA.
8. Population Sciences Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (E.J.B.).