[1] Univ Oklahoma, Hlth Sci Ctr, Dept Internal Med, Sect Cardiovasc Dis, Oklahoma City, OK USA
[2] Duke Clin Res Inst, Dept Internal Med, Dept Biostat, Durham, NC USA
[3] Duke Clin Res Inst, Dept Internal Med, Div Cardiol, Durham, NC USA
[4] Northshore Univ Hlth Syst, Dept Med, Div Cardiol, Evanston, IL 60201 USA