1. Heart and Vascular Institute, Cleveland Clinic Florida, Weston (J.H.-M.).
2. Inova Heart and Vascular Institute, Inova Fairfax Medical Center, Falls Church, VA (S.S.S.).
3. The Cardiovascular Center, Tufts Medical Center, Boston, MA (K.L.T., J.L.H., N.M.H., N.K.K.).
4. Massachusetts General Hospital, Boston (E.H.W.).
5. Medstar Georgetown University Hospital, Washington, D.C. (M.P.).
6. Beth Israel Deaconess Medical Center, Boston, MA (A.R.G.).
7. University of Washington Medical Center, Seattle (C.M.).
8. The University of Texas Medical Branch, Galveston (A.S.).
9. Baylor Scott & White Advanced Heart Failure Clinic, Dallas, TX (D.W.).
10. Allegheny Health Network, Pittsburgh, PA (M.K.).
11. Northwestern Memorial Hospital, Chicago, IL (E.V.).
12. Providence Heart Institute, Portland, OR (J.A.).
13. Cardiovascular Research Foundation, New York, NY (D.B.).