1. Baylor College of Medicine, Houston, USA
2. Methodist DeBakey Heart Center, Houston, USA
3. Mid America Heart Institute, Kansas City, USA
4. Michael E DeBakey Veterans Affairs Hospital, Houston, USA
5. Johns Hopkins University, Baltimore, USA
6. University of Texas Health Science Center, Houston, USA
7. University of Mississippi Medical Center, Jackson, USA
8. Harvard Medical School, Brigham and Women's Hospital, Boston, USA
9. University of Minnesota, Minneapolis, USA