[1] Stanford Univ, Div Cardiovasc Med, Dept Med, Sch Med, 870 Quarry Rd, Stanford, CA 94305 USA
[2] Stanford Univ, Cardiovasc Inst, Dept Med, Sch Med, 870 Quarry Rd, Stanford, CA 94305 USA
[3] Stanford Univ, Dept Med, Sch Med, Stanford, CA 94305 USA
[4] Palo Alto Med Fdn Res Inst, Palo Alto, CA USA
[5] Vet Affairs Palo Alto Hlth Care Syst, Div Cardiol, Palo Alto, CA USA
[6] Stanford Univ, Div Primary Care & Populat Hlth, Sch Med, Stanford, CA 94305 USA