1. Sakakibara Heart Institute of Okayama, Okayama, Japan
2. Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
3. Department of Surgery, Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
4. Department of Medicine, Division of Cardiovascular Medicine, Hospital of the University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA