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