[1] Stanford Univ, Palo Alto VA Hlth Care Syst, Dept Cardiovasc Med, Palo Alto, CA 94304 USA
[2] Univ Calif San Francisco, Dept Med, San Francisco, CA USA
[3] Vet Affairs Med Ctr, San Francisco, CA 94121 USA
[4] Kaiser Permanente San Francisco Med Ctr, Dept Cardiol, San Francisco, CA USA
[5] Kaiser Permanente Los Angeles Med Ctr, Div Cardiol, Los Angeles, CA USA
[6] Vet Affairs Palo Alto Hlth Care Syst, Ctr Hlth Care Evaluat, Palo Alto, CA USA