Inclusion Criteria:  Type A aortic dissection or intramural hematoma involving the aortic root/ascending aorta; Patients aged > 18 years: Symptoms started within 7 days from surgery; Primary surgical repair of acute type A aortic dissection; Any other major cardiac surgical procedure concomitant with surgery for type A aortic dissection.  Exclusion Criteria:  Patients aged < 18 years; Onset of symptoms > 7 days from surgery; Prior procedure for type A aortic dissection; Retrograde type A aortic dissection (with primary tear located in the descending aorta); Concomitant endocarditis; Type A aortic dissection secondary to blunt or penetrating chest trauma.