1. Cleveland Clinic, OH (B.L.W., K.G.T.).
2. University of Modena and Reggio Emilia, Modena, Italy (G.B.).
3. Valley Health System, Ridgewood, NJ (S.M.).
4. University of Washington School of Medicine, Seattle (J.E.P.).
5. Sahlgrenska University Hospital, Göteborg, Sweden (C.K.).
6. Duke Clinical Research Institute, Durham, NC (G.R.C.).
7. University of British Colombia, Canada (A.D.K.).
8. The Christ Hospital, Cincinnati, OH (E.J.S.).
9. Clearwater Cardiovascular and Interventional Consultants, Safety Harbor, FL (J.L.G.).
10. Saint Thomas Research Institute, LLC, Nashville, TN (R.A.P.).
11. Upper Michigan Cardiovascular Associates, Marquette (R.F.E.).
12. Cardiology Associates of Gainesville, FL (S.F.R.).
13. Iowa Heart Center, Ames (D.M.S.).
14. Virtua Health System, Camden, NJ (D.P.S.).
15. Temple University Hospital, Philadelphia, PA (E.M.C.).
16. Chula Vista Cardiac Center, CA (B.J.B.).
17. Arizona Arrhythmia Consultants, Scottsdale (D.W.R.).
18. Baylor Research Institute, Plano, TX (H.H.K.).
19. WakeMed Heart and Vascular, WakeMed Health and Hospitals, Raleigh, NC (M.T.S.).
20. Oklahoma Heart Hospital (J.C.).
21. MedStar Heart and Vascular Institute, Washington, DC (Z.E.).
22. Medtronic, Inc, Mounds View, MN (R.H., J.D.L., D.R.L., S.S.).