1. Royal Brompton and Harefield Hospital, Imperial College London, London, UK;
2. Cardiology Unit, SS. ma Annunziata Hospital, Savigliano, Italy;
3. Dipartimento of Clinical and Biological Sciences, Turin University, San Luigi Gonzaga, Torino, Italy;
4. Cardiology Unit, Città della Salute e della Scienza Hospital, University of Turin, Turin, Italy