1. From the Framingham Heart Study (T.J.W., J.C.E., E.J.B., D.L., E.C.L., R.S.V.), Framingham, Mass; Cardiology Division (T.J.W.), Massachusetts General Hospital, Harvard Medical School, Boston, Mass; National Heart, Lung & Blood Institute (D.L.), Bethesda, Md; Cardiology Section (E.J.B., R.S.V.), Preventive Medicine and Epidemiology (D.L., E.J.B., R.S.V.), Department of Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Mass.