1. Division of Cardiology, University of Texas Southwestern Medical Center, Dallas (S.G., M.S., A.P.).
2. Harvard Medical School, Boston, MA (Y.P.).
3. Department of Natural Sciences, University of North Texas at Dallas (N.L.).
4. Duke University Medical Center, Division of Cardiology, Durham, NC (R.J.M.).
5. Division of Cardiology, Brigham and Women’s Hospital, Boston, MA (H.W.).