1. Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy
2. Thrombosis Centre, Azienda Ospedaliero - Universitaria Careggi, Florence, Italy
3. Arianna Anticoagulazione Foundation, Bologna
4. Department of General and Specialized Surgery ”Paride Stefanini”, Sapienza University of Rome, Viale del Policlinico, Rome, Italy