1. Division of Cardiology, Department of Medicine, University of Chicago, Chicago, Illinois.
2. Division of Emergency Medicine, Department of Surgery, University of Utah, Salt Lake, Utah.
3. Department of Emergency Medicine, University of Southern California, Los Angeles, California.
4. Division of Cardiology, Department of Medicine, Harbor-UCLA Medical Center, Torrance, California.
5. David Geffen School of Medicine, Los Angeles, California.
6. Department of Emergency Medicine, Harbor-UCLA Medical Center, Torrance, California.