Clinical Outcomes of Transperitoneal vs Retroperitoneal Approaches of Open Aortic Repair for Abdominal Aortic Aneurysm Stratified by the Iliac Bifurcation Involvement.

Background

Aortic aneurysm involving the iliac bifurcation (AAAIB) is associated with higher rates of systemic comorbidities and increased complexity of open aortic repair (OAR), resulting in worse outcomes compared to OAR for isolated abdominal aortic aneurysm (IAAA). The Society for Vascular Surgery (SVS) practice guidelines recommend the retroperitoneal approach (RPA) for OAR in certain patients with abdominal aortic aneurysm (AAA). However, there is limited evidence to determine whether the relative advantages and disadvantages of RPA and the transperitoneal approach (TPA) change depending on whether the aneurysm distally involves the iliac bifurcation. This study aims to compare the outcomes of TPA and RPA for AAA, stratified by the iliac bifurcation involvement, in a multi-institutional, real-world setting.

Methods

The SVS Vascular Quality Initiative (VQI) database was queried for patients who underwent OAR for AAA from January 2003 to September 2024. Patients were stratified as AAAIB or IAAA based on whether the aneurysm involved the iliac bifurcation and required a distal anastomosis beyond the common iliac artery (CIA) bifurcation, or not. Baseline characteristics, as well as outcomes such as overall 30-day mortality, Major Adverse Cardiovascular Events (MACE: death, myocardial infarction, stroke), and 1-year survival, were compared between the TPA and RPA groups in patients with IAAA and AAAIB. Univariable and multivariable analyses, as well as a confirmatory analysis with inverse probability-weighted regression (IPWR), were performed.

Results

Of all reviewed patients, 17,009 were included in the final analysis, of whom 15,218 (89.5%) had IAAA, and 1,791 (10.5%) had AAAIB. Among patients with IAAA, compared to RPA, TPA was associated with higher odds of overall 30-day mortality (OR: 1.26, 95%CI: 1.05-1.49, p=0.011), MACE (OR: 1.26, 95%CI: 1.11-1.44, p=0.001), and a lower 1-year survival rate (HR: 1.23, 95%CI: 1.09-1.39, p=0.001). Among patients with AAAIB, TPA was associated with lower odds of lower extremity (LE) ischemia (OR: 0.47, 95%CI: 0.25-0.91, p=0.024) without significant differences in 30-day mortality (OR: 0.80, 95%CI: 0.42-1.51, p=0.485), MACE (OR: 0.86, 95%CI: 0.52-1.42, p=0.563), and 1-year survival (HR: 0.93, 95%CI: 0.59-1.47, p=0.768).

Conclusions

In this real-world study, involvement of the iliac bifurcation in AAA was an effect modifier for the outcomes of different OAR approaches. For patients with IAAA, compared with RPA, TPA was associated with worse 30-day mortality, MACE, and 1-year survival. Whereas for patients with AAAIB, TPA was associated with lower odds of LE ischemia, without significant differences in 30-day mortality, MACE, or 1-year survival. This study suggests that RPA may be the procedure of choice for IAAA if it is otherwise feasible. However, TPA may be the procedure of choice for patients with AAAIB who are otherwise anatomically suitable. Larger prospective studies are warranted to validate these findings.