[1] Harvard Univ, Beth Israel Deaconess Med Ctr, Sch Med, Dept Med,Cardiovasc Div,Harvard Thorndike Lab, Boston, MA 02215 USA
[2] Harvard Univ, Beth Israel Deaconess Med Ctr, Sch Med, Dept Radiol, Boston, MA 02215 USA
[3] NHLBI, Framingham Heart Study, Framingham, MA USA
[4] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Dept Internal Med,Div Cardiol, Boston, MA USA