1. Division of Cardiovascular Medicine and Cardiovascular Institute, Stanford University, Stanford, California
2. Section of Cardiology, Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas3Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, Houston, Texas
3. Division of Cardiovascular Medicine, Veterans Affairs Palo Alto Health Care System, Palo Alto, California
4. Division of Cardiovascular Medicine and Cardiovascular Institute, Stanford University, Stanford, California4Division of Cardiovascular Medicine, Veterans Affairs Palo Alto Health Care System, Palo Alto, California