[1] Denver VA Med Ctr, Cardiol Sect, Denver, CO 80220 USA
[2] Univ Colorado, Hlth Sci Ctr, Dept Med, Denver, CO 80262 USA
[3] Univ Colorado, Hlth Sci Ctr, Dept Prevent Med & Biometr, Denver, CO 80262 USA
[4] Colorado Permanente Med Grp, Clin Res Unit, Denver, CO USA
[5] Univ Missouri, Div Cardiol, Kansas City, MO 64110 USA
[6] VA Puget Sound Hlth Care Syst, Seattle, WA USA