Preemptive Embolization of Abdominal Aortic Aneurysm Sac Side Branch Arteries Promotes Early Sac Shrinkage after Endovascular Aneurysm Repair 1

Background: The association between the occlusion rate of the side branch arteries branching from the abdominal aortic aneurysm sac and aneurysm sac shrinkage is unclear. We aimed to evaluate the efficacy of preemptive embolization of multiple side branch arteries branching from the abdominal aortic aneurysm sac in early aneurysm sac shrinkage after endovascular aneurysm repair. Methods: Patients undergoing endovascular aneurysm repair of abdominal aortic aneurysms, with or without preemptive embolization of multiple side branch arteries, including the inferior mesenteric artery and lumbar arteries, between January 2016 and August 2021, were retrospectively evaluated. Preemptive embolization was introduced at our institution in January 2018 and has been performed in all patients who undergo endovascular aneurysm repair since then. We compared occlusion rates of the side branch arteries, frequency of type 2 endoleaks, changes in aneurysm sac size, percentage of aneurysm sac size decrease, and frequency of reduction in the aneurysm sac diameter by > 5 mm. Results: The study included 43 patients in the embolization group and 20 in the nonembolization group. Preemptive embolization was successfully performed without any ischemic complications. The total occlusion rate of side branch arteries was significantly higher in the embolization group than in the nonembolization group (70.2% vs. 29.3%, P < 0.05). At 24 months of follow-up, the type 2 endoleak frequency was significantly lower in the embolization group than in the nonembolization group (6.9% vs. 31.6%, P < 0.05). The frequency of reduction in the aneurysm sac diameter by > 5 mm was significantly higher in the embolization group than in the nonembolization group at 24 months (62.1% vs. 31.6% P < 0.05). The optimal cutoff value for the total occlusion rate of the side branch arteries to achieve reduction in the aneurysm sac diameter by > 5 mm at 24 months, after endovascular aneurysm repair, was 66.7% in all patients (area under the curve = 0.634; sensitivity = 62.5%; specificity = 70.8%). These findings suggest that occluding 66.7% or more of the side branch arteries may result in early aneurysmal shrinkage. Conclusions: Preemptive embolization of multiple side branch arteries, branching from the abdominal aortic aneurysm sac, may contribute to early aneurysm sac shrinkage; this may serve as a marker for fewer late complications after endovascular aneurysm repair.