1 Division of Cardiology, Medical University of South Carolina and Ralph H. Johnson Veteran Affairs Medical Center, Charleston, SC.
2 Division of Cardiology, Department of Medicine, Brigham and Women's Hospital, Boston, MA.
3 Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC.
4 Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, TX.
5 Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC; Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC.