[1] Rocky Mt Reg VA Med Ctr, Div Cardiol, Cardiol 111,Bldg F2,Room 143, Aurora, CO 80045 USA
[2] Northwestern Univ, Dept Med, Div Cardiol, Feinberg Cardiovasc Res Inst,Feinberg Sch Med, Chicago, IL 60611 USA
[3] Harvard Med Sch, Brigham & Womens Hosp, Div Cardiovasc, Boston, MA 02115 USA
[4] Univ Colorado, Div Cardiol, Sch Med, Aurora, CO USA