Type A aortic dissections represent a surgical emergency, yet there are those patients who do not receive immediate surgical treatment after the onset of their symptoms. The natural history of these patients, their reasons for delay in presentation or surgical correction, and their comparative clinical courses are not well defined. Data on 195 patients with type A dissections followed at Yale New Haven Hospital between 1985 and 2005 have been collected prospectively and retrospectively. Ninety-two (47.2%) patients received surgical treatment ¡à 48 hours after the initial onset of pain or did not receive any surgical treatment (Group A); the remaining 103 patients underwent immediate operative repair within 48 hours of symptom onset (Group B). Median follow-up was 41.8 months (range 0-386). Patients in Group A were older (68.8 vs. 59.3 yrs, p = 0.0005) and had a higher incidence of debilitating comorbidities: coronary artery disease (42.5% vs. 14.6%, p