IntroductionAneurysmal sac regression is a predictor of long-term outcomes after endovascular aneurysm repair (EVAR). This study aimed to compare a large cohort of TREO and non-TREO endografts over a mid-term follow-up and compare abdominal aortic aneurysm sac regression. The hypothesis was that TREO endografts have an increased sac regression by 24 mo. MethodsThis is a retrospective analysis of all EVARs completed at a single institution between 2015 and 2024. Clinical and imaging data were collected from an institutional database and patients’ records. The analysis included all TREO and age, sex, anticoagulation use and current smoking-matched non-TREO endografts that satisfied anatomic indications for use of the TREO graft. The primary outcomes were sac regression at 12 and 24 mo, and secondary outcomes were rates of mortality, endoleak, and reintervention. ResultsTwenty-one TREO grafts were matched to 68 non-TREO grafts. The groups were similar in demographics, comorbidities, and preoperative anatomy. Preoperative abdominal aortic aneurysm sac size was larger in the TREO cohort. The mean reduction in sac size in mm was greater in the TREO cohort compared to the non-TREO cohort (−12.6 ± 8.95 versus −7.83 ± 7.74 mm, P = 0.039) over the study period. Cox regression analysis identified the TREO stent graft to be associated with 1-y sac regression (hazard ratio = 2.42, P = 0.019). The incidence of all-cause endoleaks, reintervention, and mortality were similar between cohorts. ConclusionsThese findings suggest that the TREO endograft offers better mid-term outcomes with respect to sac regression with no differences in the incidence of endoleak, mortality, or reintervention.