Arianna Anticoagulazione Foundation, Bologna, Italy. Angiology Unit, SS Filippo and Nicola Hospital, Avezzano, L'Aquila, Italy. Department of Internal Medicine, University of Insubria, Varese, Italy. Cardiology Clinic, Thrombosis Centre, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy. Thrombosis Centre, AOU Careggi, Firenze, Italy. Hemostasis and Thrombosis Center, Department of Laboratory Medicine, AO Istituti Ospitalieri, Cremona, Italy. Hematology Department, S. Bortolo Hospital, Vicenza, Italy. Department of Clinical Medicine, University of Padua, Padua, Italy.