1. Department of Cardiac Surgery; Hospital Dr.Negrín; Las Palmas de Gran Canaria Spain
2. Department of Cardiac Surgery; Fundación Jiménez Díaz; Madrid Spain
3. Department of Cardiac Surgery; Hospital de Navarra; Pamplona Spain
4. Department of Epidemiology; Fundación Jiménez Díaz; Madrid Spain
5. Department of Cardiology; Fundación Jiménez Díaz; Madrid Spain