1. Cardiovascular Institute, Warren Alpert Medical School of Brown University, Providence, RI (F.V.L., H.D.A., V.K., J.D.A.).
2. Duke Clinical Research Institute, Durham, NC (P.M., D.W., T.W., E.H.W.).
3. Department of Cardiovascular Diseases, Rush University Medical Center, Chicago, IL (N.M.).
4. Penn State Heart and Vascular Institute, Hershey, PA (I.C.G.).
5. Northside Hospital Cardiovascular Institute, Atlanta, GA (C.G.).