1. Cardiovascular Division, Department of Medicine, Veterans Affairs Boston Healthcare System, West Roxbury, MA, USA
2. Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, USA
3. Harvard Medical School, Boston, MA, USA
4. Central Maine Medical Center, Lewiston, ME, USA
5. University of Pittsburgh, Pittsburgh, PA, USA
6. Medical University of South Carolina, Charleston, SC, USA
7. Cardiovascular Division, Department of Medicine, Ralph H Johnson Veterans Affairs Medical Center, Charleston, SC, USA