1. Department of Heart and Vessels, Careggi Hospital, Viale Morgagni 85, 50134 Florence, Italy
2. Department of Cardiothoracic Surgery, Academic Hospital, 6202 AZ Maastricht, The Netherlands
3. Cardiology Unit, Barone Romeo Hospital, 98066 Patti Messina, Italy
4. Cardiac Surgery Units, Community Hospital, 25128 Brescia, Italy