1. Department of Critical Care Medicine, Division of Cardiology, Department of Medicine, University of Alberta , 8440-11 St, Edmonton, AB T6G 2B7 , Canada
2. Coronary Care Unit, Instituto Nacional de Cardiología Ignacio Chávez , México City , México
3. Inova Heart and Vascular Institute, Inova Fairfax Medical Campus , Falls Church, VA , USA