Changes in stent-graft orientation after frozen elephant trunk treatment in aortic arch aneurysm.

Background: Changes in stent graft (SG) orientation after frozen elephant trunk (FET) treatment for aortic arch aneurysms are not well understood. This study investigated changes in SG orientation and their effects on aortic events after FET for aortic arch aneurysms. Methods: This study included 57 patients with true aneurysms who underwent elective total arch replacement using FET between 2016 and 2023. Postoperative SG angle, descending aortic (DA) diameter at the end of the SG, and the DA angle were measured retrospectively by using enhanced computed tomography (CT). Results: Median patient age was 74 years. The median stent size was 33 mm, and the stent length was 12 cm (range, 23-37 mm and 6-15 cm). Enhanced CT showed that all the patients had completely thrombosed aneurysms after the procedure. Aortic events (dissection or type Ib leaks) were observed in four patients during the follow-up period. The diameter of the DA at the end of the SG and the DA angle increased in recent periods (P=0.04 and P=0.01, respectively). The SG angle changed to an obtuse angle in the recent periods (P<0.0001). The probability of postoperative aortic events did not correlate with changes in SG orientation but with the ratio of recent postoperative descending diameter to preoperative descending diameter (P=0.04). Conclusions: The descending aorta into which the SG was inserted showed flattening and widening movements owing to the spiring back force. One of the factors related to aortic events was dilation of the postoperative DA due to oversizing of the SG.