IYSC03 - Evaluation of Type 2 Endoleak Risk Associated with Preemptive Total Side Branch Embolization in Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm

Objectives: Type 2 endoleak (T2EL) following endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) has been linked to aneurysm-related adverse events, highlighting the need for effective prevention. Preemptive total side branch embolization has been reported to reduce T2EL occurrence, yet some cases still develop T2EL. This study aimed to evaluate the outcomes of preemptive total side branch embolization and identify independent risk factors for T2EL after EVAR.

Methods: We retrospectively analyzed 400 consecutive patients who underwent preemptive total side branch embolization during EVAR for AAA between April 2018 and March 2025. Patients with at least 6 months of follow-up were included. The primary endpoint was the occurrence of T2EL. Potential predictive factors—including patient demographics, aneurysm morphology, and procedural characteristics—were evaluated by univariate and multivariable logistic regression analyses. Variables with P < 0.10 in univariate analysis were entered into multivariable models, with age and sex included as covariates.

Results: During a mean follow-up of 36.4 ± 20.5 months, T2EL occurred in 43 of 400 patients (10.8%), and additional intervention for aneurysm enlargement related to T2EL was required in 4 cases (1.0%). Compared with patients without T2EL, those with T2EL had significantly larger aneurysm diameters (58.1 ± 12.0 vs. 52.8 ± 10.8 mm, P = 0.02), more patent lumbar arteries (3.1 ± 1.8 vs. 2.3 ± 1.6, P < 0.01), and more residual lumbar arteries (1.0 ± 1.1 vs. 0.4 ± 0.8, P < 0.01).
Multivariable analysis identified aneurysm diameter (OR 1.03, 95% CI 1.00–1.06, P = 0.023) and the number of residual lumbar arteries (OR 1.50, 95% CI 1.06–2.12, P = 0.024) as independent predictors of T2EL (Table I).
The incidence of T2EL increased with the number of residual lumbar arteries: 0 (6.9%), 1 (14.7%), 2 (24.2%), and ≥3 (31.3%), with adjusted ORs of 2.32–5.41 compared to 0 (Table II).

Conclusions: Preemptive total side branch embolization markedly reduced the incidence of type 2 endoleak compared to our historical cohort prior to the introduction of this technique (10.8% vs. 24.5%). This finding indicates that preemptive embolization contributes substantially to the prevention of type 2 endoleak after EVAR. However, aneurysm diameter and the number of residual lumbar arteries remained independent risk factors even after embolization. To further minimize the risk, it is essential to reduce the number of residual branches as much as feasible while balancing fluoroscopy time and contrast use.