1. Cardiovascular Division, Department of Medicine, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
2. The Division of Cardiology, Department of Medicine, John Cochran Veterans Affairs Medical Center, St. Louis, MO 63106, USA.
3. Department of Cardiology, AtlantiCare Regional Medical Center, Pomona, NJ 08240, USA.
4. Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.