[1] Dartmouth Hitchcock Med Ctr, Lebanon, NH USA
[2] Geisel Sch Med Dartmouth, Dartmouth Inst, Hanover, NH USA
[3] Duke Univ, Clin Res Inst, Durham, NC USA
[4] Univ Calif Los Angeles, Div Cardiol, Los Angeles, CA USA
[5] Brigham & Womens Hosp, Div Cardiovasc Med, Boston, MA USA
[6] Northwestern Univ, Div Cardiol, Chicago, IL USA
[7] Duke Univ, 200 Trent Dr,4th Floor,Room 4225, Durham, NC 27710 USA