Saccular and Fusiform Abdominal Aortic Aneurysms Treated With Endovascular Repair Differ in Presentation and Treatment Threshold: Analyses Using a National Clinical Database in Japan.

BACKGROUND:Saccular abdominal aortic aneurysms (AAAs) are considered to be at higher risk of rupture than fusiform AAAs, but not much is known about the extent of this risk. Therefore, this study aimed to compare the rupture presentation between fusiform and saccular AAAs. METHODS AND RESULTS:This is a retrospective cohort study on 27 290 patients who underwent primary endovascular repair for a degenerative AAA between 2016 and 2019, and who were registered in the National Clinical Database in Japan. At operation for nonruptured case, the aneurysm diameter was significantly smaller in saccular AAAs than in fusiform AAAs (median, 44.0 versus 51.0 mm; P<0.001). Similarly, aneurysm diameter at rupture was significantly smaller in saccular AAAs than in fusiform AAAs (median, 55.6 versus 68.0 mm; P<0.001). The likelihood of repair for rupture was significantly higher in saccular AAAs than in fusiform AAAs in the 40- to 54-mm diameter range, in which saccular morphology was found to be an independent risk factor for rupture against fusiform morphology by adjusting for sex and aneurysm diameter (odds ratio, 2.54 [95% CI, 1.75-3.69]). In addition, receiver-operating characteristic curve analysis revealed that the cutoff diameter to predict rupture was smaller in saccular AAAs than in fusiform AAAs (50.5 and 59.5 mm, respectively) based on the Youden index. CONCLUSIONS:Saccular AAAs presented at smaller diameters than fusiform AAAs in patients with ruptured AAAs treated with endovascular aortic repair, which supports the idea that saccular AAAs should be treated at smaller diameters.