[1] Stanford Univ Hosp, Dept Internal Med, Palo Alto, CA USA
[2] Univ Colorado, Sch Med, Div Internal Med, Aurora, CO 80045 USA
[3] Colorado Cardiovasc Outcomes Res Consortium, Denver, CO USA
[4] Thoratec Corp, Pleasanton, CA USA
[5] Univ Colorado, Sch Med, Div Cardiol, Sect Adv Heart Failure & Transplantat, Aurora, CO 80045 USA
[6] Univ Missouri, MKC, St Lukes Mid Amer Heart Inst, Kansas City, MO 64110 USA