Pre-emptive Embolization of Aortic Side Branches Prior to Endovascular Aortic Repair to Prevent Type II Endoleaks: A Systematic Review and Meta-Analysis

Abstract

Introduction: Endoleak occurs in over 10% of patients after endovascular aortic repair (EVAR) of aortic aneurysm. Type II endoleaks are the most common type and may cause late sac expansion and rupture. To prevent this, pre-emptive embolization of aortic side branches (mainly inferior mesenteric artery [IMA] and lumbar arteries [LA]), before or during EVAR has been suggested. Our aim was to review the current evidence of this prophylactic treatment. Methods: This was a systematic review and meta-analysis following the PRISMA guidelines. The MEDLINE and Scopus databases were used to search for related articles until March 2019. Search algorithm included keywords “type II endoleak” and “EVAR [OR] endovascular aortic repair” with combination of “inferior mesenteric artery”, “lumbar artery”, "accessory renal artery” or “median sacral artery”. After screening, original studies reporting outcome of pre-emptive embolization of aortic side branches were included in the review. An assessment of the quality of the included studies, as well as data extraction, was performed by two independent observers. Statistical analysis was performed using OpenMeta[Analyst] (www.cebm.brown.edu/openmeta/index.html). Results: A total of 3,777 publications were identified based on search strategy. After eliminating duplicated entries, review of titles and abstracts, 13 retrospective cohort studies, including 1,586 patients, comparing pre-emptive embolization to standard EVAR therapy were identified. All studies were scored as medium or low quality. Another two single-arm series were also reviewed for technical success and complications. Results from eleven studies showed that technical success of IMA and LA embolization were 84.6% (230/272) and 67.9% (91/134) respectively. Based on thirteen studies, the incidence of type II endoleaks was 18.0% (107/593) in the embolization group vs 35.8% (355/993) in the control group, odds ratio 0.35 (95% C.I. 0.23 - 0.53). Based on ten studies, the incidence of re-intervention was 1.5% (7/480) in the embolization group vs. 11.1% (74/668) in the control group, odds ratio 0.14 (95% C.I. 0.07 - 0.29). In six studies, frequency of sac growth after EVAR was 4.5% (15/333) in the embolization group vs. 14.2% (68/478) in controls, odds ratio 0.17 (95% C.I. 0.05 - 0.65). Regarding complications, ten of 108 patients (9.3%) in one study reported non-specific abdominal pain after embolization, and all resolved with overnight rehydration. One patient (0.01%), in the same study, who had prior right hemicolectomy, died after IMA embolization. Conclusion: This systematic review and meta-analysis suggests that pre-emptive aortic side branch embolization prior to standard EVAR may reduce the incidence of type II endoleaks and re-interventions. Studies report high technical success rates, particularly for IMA embolization. Caution is needed when disturbed collateral colonic circulation is present. However, there is a lack of high-quality unbiased studies in this field. To conclude that embolization should be routinely performed, randomized evidence of any benefits and cost-effectiveness is needed. Disclosure: Nothing to disclose