1. Clinical Trials Center, Cardiovascular Research Foundation, New York, NY (B.R., S.C., A.C., O.B.-Y., G.W.S.).
2. New York-Presbyterian Hospital/Columbia University Medical Center, New York, NY (O.B.-Y., N.J.L., G.W.S).
3. Department of Cardiovascular Medicine, Mayo Clinic College of Medicine, Rochester, MN (B.J.G.).
4. Piedmont Heart Institute, Atlanta, GA (W.M.B.).
5. John Radcliffe Hospital, Oxford, United Kingdom (A.P.B., D.P.T.).
6. Imperial College of Science, Technology and Medicine, London, United Kingdom (P.W.S.).
7. Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands (A.P.K.).
8. Department of Surgery, University Hospitals Cleveland Medical Center, OH (J.F.S.).