1. Division of Cardiology, University of Chicago, IL (N.U., T.I., D.R., J.R., G.K., G.S.).
2. Cardiovascular Research Foundation and Division of Cardiology, Columbia University, New York, NY (D.B.).
3. Division of Cardiology, Northwestern University, IL (J.D.R., E.E.V.).
4. Divisions of Cardiology and Surgery, University of Utah, Salt Lake City (S.G.D., C.H.S.).
5. Division of Cardiology, Stanford University, Palo Alto, CA (J.J.T.).