1. Division of Cardiovascular Medicine; University of Pennsylvania; Philadelphia PA USA
2. Collaborative Health Studies Coordinating Center; University of Washington; Seattle WA USA
3. Section of Electrophysiology, Division of Cardiology; University of California; San Francisco CA USA
4. Cardiac, Thoracic, and Vascular Department; Fondazione IRCCS Policlinico S. Matteo; Pavia Italy
5. Division of Cardiology; Medical University of South Carolina; Charleston SC USA
6. Department of Cardiology; Karolinska University Hospital; Stockholm Sweden
7. Division of General Internal Medicine Section; Veterans Affairs Medical Center; San Francisco CA USA
8. Departments of Medicine, Epidemiology and Biostatistics; University of California; San Francisco CA USA