1. From the National Heart, Lung, and Blood Institute’s Framingham Heart Study, Framingham, Mass (R.S.V., D.L.); the Divisions of Cardiology and Clinical Epidemiology, Beth Israel Hospital, Boston, Mass (D.L.); the Department of Preventive Medicine and Epidemiology, Boston University School of Medicine, Boston, Mass (R.S.V., D.L.); and the National Heart, Lung, and Blood Institute, Bethesda, Md (D.L.).