1. Department of Cardiac Surgery, Golden Jubilee National Hospital, Agamemnon St, Clydebank, G81 4DY Glasgow, UK
2. Division of Cardiovascular Medicine, John Radcliffe Hospital, Oxford, UK
3. Department of Cardiovascular Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
4. Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, NY, USA