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Monday, September 13, 2021

Predictive Value of Preprocedural Computed Tomography Angiography for the Technical Success of Transarterial Embolization of Type II Endoleaks Arising from the Lumbar Arteries

Predictive Value of Preprocedural Computed Tomography Angiography for the Technical Success of Transarterial Embolization of Type II Endoleaks Arising from the Lumbar Arteries


Clinical question
Can preprocedural computed tomography angiography (CTA) predict treatment success of transarterial embolization in patients with Type II endoleaks fed by lumbar arteries?

Take-away point
Presence of a traceable path of the feeding lumbar/iliolumbar artery on preprocedural CTA is associated with increased rates of technical success.

Reference
Contrella, B., Wilkins, L., Sheeran, D., et al. Predictive value of preprocedural computed tomography angiography for the technical success of transarterial embolization of type II endoleaks arising from the lumbar arteries. Journal of Vascular and Interventional Radiology. 2021;32(7):1016-1021.

Click here for abstract

Study design
Retrospective cohort study

Funding source
Self-funded or unfunded

Setting
Single institution, University of Virginia, Charlottesville, VA

Figure


Figure. Computed tomography angiography (CTA) maximum intensity projection images in oblique sagittal (a) and oblique axial (b) planes demonstrated opacified arterial collateral vessels (white arrows) extending from the aneurysm sac to the iliolumbar artery. (c) Digital subtraction angiogram with a flush catheter in the aorta during subsequent transarterial treatment demonstrated an opacified path (black arrow) extending from the internal iliac artery to the aneurysm sac, corresponding with prior CTA. (d) Technically successful passage of a microcatheter into the aneurysm sac, with location confirmed using contrast medium injection. Sac embolization was subsequently performed using coils and ethylene vinyl alcohol copolymer.

Summary


Type II endoleak, the most common type to occur after endovascular aneurysm repair (EVAR), occurs in 8-30% of patients who undergo the procedure based on post-procedural surveillance imaging. While most spontaneously resolve on further follow-up, some warrant treatment (e.g. persistence, increased aneurysm size). These endoleaks are often treated either by embolizing the feeder vessel, which most commonly arises from lumbar arteries or the inferior mesenteric artery (IMA), or by direct puncture and embolization of the aneurysm sac itself, via either translumbar or transcaval routes. The procedure of choice is usually determined by a combination of CTA imaging, prior interventions, and operator preference, as there is little data to support one method over the other. Additionally, 17-24% of treated type II endoleaks require multiple procedures to achieve technical and clinical success.

In this retrospective cohort study, all patients who underwent endovascular embolization for type II endoleak due to a lumbar artery feeder over a 9.5-year period were analyzed. Inclusion required a post-EVAR CTA demonstrating the endoleak. Patients who ultimately underwent translumbar or transcaval sac embolization during the first embolization procedure or subsequently were included. Patients with feeding vessels arising from the IMA were excluded. For each patient, post-EVAR CTA imaging was reviewed by 2 interventional radiologists. The presence or absence of a feeding vessel with continuous traceability between the source lumbar artery to the aneurysm sac was determined. Discrepancies in traceability were reviewed by a third interventional radiologist. All image reviewers were blinded to eventual procedure outcome.

57 procedures were analyzed in 54 patients. These procedures were categorized as either traceable (18, 32%) or non-traceable (39, 68%). Patient demographics, anticoagulation, comorbidities including DM, HTN, COPD, malignancy or CAD, as well as history of previous vascular surgery all did not differ between groups. Technical success was defined as microcatheter passage into the aneurysm sac with subsequent use of a liquid embolic to embolize the aneurysm sac. Technical success was achieved in 16 (89%) of the patients with feeder vessel traceability on CTA and in 10 (26%) of those in the non-traceable group (p < 0.001). In the 31 cases that were not successful using transarterial embolization, patients were treated with percutaneous aneurysm sac puncture (17, 55%), embolization of the endoleak nidus through the arc of Riolan to the IMA (5, 16%), transcaval aneurysm sac puncture (2, 6%), additional endograft placement (1, 3%), or active surveillance (6, 19%).

In 6 of the 57 cases (11%), a type I or type III endoleak were found on angiography in addition to the type II endoleak. These were all treated either during the same procedure or during subsequent procedures. 1 major complication occurred in the traceable group and 2 occurred in the non-traceable group (p = 0.88). No minor complications occurred in the traceable group and 1 occurred in the non-traceable group (p = 0.46). Major complications included a femoral artery pseudoaneurysm, brachial artery pseudoaneurysm, and hemorrhagic stroke. The single minor complication was post-procedural nausea requiring overnight admission.

Commentary


This study demonstrated relatively high rate of technical success in transarterial treatment of lumbar-fed type II endoleaks in patients with a traceable feeding vessel on pre-procedural CTA. The investigators claim a paucity of previous data establishing superiority between transarterial embolization or direct sac puncture for treating type II endoleak. The investigation has several limitations, including variability in CTA quality. The authors astutely point out the possibility of false negatives resulting from otherwise traceable feeding vessels being missed due to lower image quality. There is also the issue of variability in technique and tools used for vessel catheterization and embolization. This study did not statistically analyze differences between groups to evaluate for differences in techniques and tools that may have confounded the rate of technical success between groups. Lastly, the overall technical success of all procedures (46%) was lower than previous studies. This may be explained by the initial default to transarterial approach instead of an aortogram followed by interventionalist discretion as done in other investigations. 

Given the significant result of improved technical success with traceability on CTA, further investigations should be expanded to similar analysis regarding feeding vessels from the IMA. A larger retrospective trial that further evaluates the utility of traceability with more uniform CTA study quality would be a promising next step in resolving a blind spot in the evidence, helping to assist interventionalists in procedure selection for this common problem.

Post Author
Jared Edwards, MD
General Medical Officer
Medical Readiness Division
Naval Surface Forces Pacific, San Diego, CA
@JaredRayEdwards

Edited and formatted by @NingchengLi

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