For a study, researchers sought to determine if the segment of moderate aortic dilation increases the risk of ATAD. They found 667 ATAD patients with MAD <5.5 cm using the International Registry of Acute Aortic Dissection (IRAD) database from May 1996 to October 2016. Patients were classified according to the location of the biggest proximal aortic segment (AR or AA). Patients who had known hereditary aortopathy were eliminated. MADs were compared between the AR and AA groups at the dissection time. Operation, postoperative results and long-term survival were all secondary outcomes.

About 79.5% (n=530) of patients with ATAD with a MAD of <5.5 cm were in the AA group, and 20.5% (n=137) were in the AR group. ARs dissected at a substantially smaller diameter than AAs (median MAD 4.6 cm [IQR: 4.1-5.0 cm]) (P< 0.01). AR patients were substantially younger than AA patients (58.5+13.0 years vs. 63.2+13.3 years; P<0.01), and they were more likely to be male (78% vs. 65%; P<0.01). There were no differences in postoperative and long-term results across groups.

ATAD appears to develop at lower diameters in patients with little dilatation of the AR vs. the AA (4.6 vs. 4.8 cm). These findings might impact future consensus guidelines for the care of aortic disease patients.