ObjectiveTo evaluate outcomes achieved after implementing a treatment strategy for non-A non-B (NANB) (B 1-2 D according to the latest consensus document of the Society of Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) acute aortic dissection (AAD). MethodsThis retrospective observational study adhered to the STROBE checklist. All cases of NANB AAD (B 1-2 D) treated at our Institution between January 2016 and December 2022 were reviewed. Morbidity, mortality, aortic-related reintervention, and remodelling were analysed. ResultsAmong 519 cases of acute aortic syndrome, n=22 (4.2%) patients presented with NANB AAD (B 1-2 D) (n=16,72.7% men, mean age 61.5 years+/14.7). Eleven cases were managed with best medical treatment (BMT) alone. Among them, one patient (9.1%) died suddenly two days after diagnosis for aortic rupture. Frozen elephant trunk procedure (FET) was required in the remaining 11 patients: 7(31.8%) needed emergent operation for risks of impending aortic rupture/retrograde AD extension and 4(26.7%) underwent delayed surgery within a month from initial presentation. Overall, in-hospital mortality was 9.1% with both FET and BMT. At a median follow-up of 40 months (range 2 days-200 months) no other deaths occurred. A statistically significant differences in the rate of FL thrombosis (100% vs 55.5%, p=.033) and a significant positive aortic remodelling in zone 3 (p<.001) and 4 (p=0.038) were reported in operated versus medically managed patients. ConclusionThe best treatment for NANB is not established. We advocate for medical stabilisation with an operative approach that favours open surgery in the acute post dissection period, promotes aortic remodelling and carries acceptable risk in centres where FET is performed routinely.