1. From the University of Texas Southwestern Medical Center at Dallas (N.F., J.L.H., K.M.S., P.S.B., G.C.-R.; B.D.L.); Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (N.F., J.L.H., K.M.S., P.S.B., G.C.-R.; B.D.L.); Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic Rochester, MN (B.A.B.); and Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston (G.D.L.).