1. Division of Cardiology, Duke University Hospital , 2301 Erwin Rd, Durham, NC 27710 , USA
2. Department of Anesthesiology, Duke University Hospital , 2301 Erwin Rd, Durham, NC 27710 , USA
3. Division of Cardiology, Cleveland Clinic Foundation , 9500 Euclid Ave, Cleveland, OH 44195 , USA
4. Division of Cardiovascular Surgery, Northwestern , 676 N. St. Clair St., Chicago, IL 60611 , USA