1. South Denver Cardiology Associates, Littleton, CO (D.A.).
2. The Heart Center of Northeast Georgia Medical Center, Gainesville (A.G.).
3. Columbia University Medical Center, New York, NY (M.W.).
4. University of Maryland Medical Center, Baltimore (B.R.).
5. Stony Brook Medical Center, NY (A.S.).
6. Huntsville Hospital Heart Center, AL (J.G.).
7. Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA (M.K.).
8. University of Pittsburgh Medical Center, PA (N.A.M.E.).
9. Massachusetts General Hospital, Boston (K.H.).