[1] UCSF, Div Cardiol, San Francisco, CA USA
[2] Oregon Hlth & Sci Univ, Knight Cardiovasc Inst, Portland, OR 97201 USA
[3] UCSF, Dept Epidemiol & Biostat, San Francisco, CA USA
[4] Univ Washington, 4Cardiovasc Hlth Rsch Unit, Seattle, WA USA
[5] Univ Washington, Dept Epidemiol, Seattle, WA 98195 USA
[6] Washington Univ, Sch Med, HRV Lab, St Louis, MO USA