1. Division of Cardiology, Electrophysiology Section, University of California, San Francisco, 505 Parnassus Avenue, M-1180B, Box 0124, San Francisco, CA, USA
2. The Knight Cardiovascular Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, USA
3. Department of Epidemiology and Biostatistics, University of California, San Francisco, 505 Parnassus Avenue, M-1180B, Box 0124, San Francisco, CA, USA
4. Cardiovascular Health Research Unit, Department of Epidemiology, University of Washington, 1730 Minor Ave, Suite 1360, Seattle, WA, USA
5. School of Medicine, Washington University, HRV Lab, 660 South Euclid Avenue, Campus Box 8215, St. Louis, MO, USA