Division of Cardiology, Department of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas. Division of Cardiology, Duke University School of Medicine, Durham, North Carolina; Duke Clinical Research Institute, Durham, North Carolina. Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi. Brigham and Women's Hospital Heart & Vascular Center and Harvard Medical School, Boston, Massachusetts. Division of Cardiology, Duke University School of Medicine, Durham, North Carolina; Duke Clinical Research Institute, Durham, North Carolina. Electronic address: stephen.greene@duke.edu.