1. Division of Cardiovascular Medicine, Department of Medicine; Penn Cardiovascular Outcomes, Quality, and Evaluative Research Center; and Leonard Davis Institute for Health Economics, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
2. UPMC Heart and Vascular Institute, Harrisburg, PA, USA
3. Division of Cardiovascular Medicine, Department of Medicine, Duke University, 2400 Pratt St, Durham, NC 27710, USA
4. Duke Clinical Research Institute, Duke University, PO Box 17969, Durham, NC 27715, USA