Evaluation of sac volume regression after aortic aneurysm sac embolization with shape memory polymer plugs in patients undergoing endovascular aneurysm repair

Objective: Endovascular aneurysm repair (EVAR) is widely used for infrarenal abdominal aortic aneurysms, offering improved short-term outcomes compared with open repair. However, long-term durability is limited by the need for surveillance and reintervention, often related to sac growth and endoleak. Prophylactic sac embolization using shape memory polymer (SMP) plugs—a porous, bioabsorbable polyurethane scaffold designed to promote thrombosis and tissue ingrowth—has been evaluated in early feasibility studies. This study represents the first global, multicenter real-world analysis of SMP use during EVAR. Methods: A multicenter, retrospective, two-arm computed tomography angiography (CTA)-based sac regression analysis was performed in 97 highly selected patients meeting prespecified eligibility criteria. Fifty-six patients underwent EVAR with prophylactic sac management (EVAR-PSM) using SMP between 2019 and 2023, including 31 treated prospectively in the abdominal aortic aneurysm-SHAPE early feasibility studies and 25 treated in real-world practice. Forty-one patients underwent standard EVAR between 2014 and 2019 at a single center and met identical inclusion/exclusion criteria, including aneurysm size thresholds, sac volume parameters, infrarenal stent grafts use within instructions for use, serial CTA availability, and exclusion of adjunctive branch vessel embolization. Sac regression (>10% volume reduction between 30-day and 1-year CTA) was assessed. Thrombus burden and patent accessory vessels were analyzed in all patients; packing density and plug proximity to accessory vessels were analyzed in the EVAR-PSM group. Results: Hypertension was more prevalent in controls (98% vs 77%, P = .01), whereas prior myocardial infarction was less common (0% vs 17%, P = .01). In the treatment group, a mean of 59 plugs per patient were implanted, yielding a mean packing density of 129%. Sac regression >10% at 1 year occurred more frequently in the EVAR-PSM group (79% vs 51%, P < .01). Type II endoleak occurred in 40% vs 49% (P = .4), and secondary reintervention rates were similar (2.4% vs 1.8%, P < .90). No aneurysm ruptures occurred. One-year survival was similar between groups (100% vs 96%, P = .50). On multivariable analysis, SMP treatment was independently associated with sac regression (odds ratio: 4.13 [1.5-12.0], P < .01). Within the treatment group, shorter plug distance to patent branch vessels was independently associated with sac regression (odds ratio: 0.54 [0.30-0.71], P < .01), while packing density and thrombus burden were not. Conclusions: In this multicenter analysis of controlled and real-world data, prophylactic sac embolization with SMP was associated with significantly greater sac regression compared with standard EVAR. Effective sac remodeling appears influenced by plug proximity to branch vessels.