1. Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
2. Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
3. Cardiovascular Medicine, Case Western Reserve University, Cleveland, OH
4. Cardiovascular Medicine, University of Wisconsin, Madison, WI
5. Cardiovascular Medicine, Mayo Clinic, Rochester, MN