1. Department of Thoracic Surgery, University Medical Center Essen—Ruhrlandclinic , Essen, Germany
2. Department of Cardiac Surgery, University Hospital of Angers , Angers, France
3. Department of Cardiothoracic Surgery, Barts Health NHS Trust, St Bartholomew's Hospital , London, UK
4. Department of Cardiothoracic Surgery, Castle Hill Hospital , Cottingham, UK