Fenestrated endovascular repair with large device diameters (34- to 36-mm) is associated with type 1 and 3 endoleak and reintervention

Large-Diameter Fenestrated Endograft Repair of Abdominal Aortic Aneurysms Is Not Associated With Medium-Term Outcomes

INTRODUCTION

Recent data suggests that infrarenal abdominal aortic aneurysm (AAA) endovascular repair (EVAR) with large diameter grafts (LGs) may have a higher risk of endoleak and reintervention. However, this has not been studied extensively for fenestrated endovascular aneurysm repair (fEVAR). We, therefore, sought to evaluate the outcomes of patients undergoing fEVAR with large-diameter endografts.

METHODS

Patients from the national Vascular Quality Initiative registry who underwent fEVAR for intact juxtarenal AAA were identified. Patients with genetic causes for aneurysms, those with prior aortic surgery, and those undergoing repair for symptomatic or ruptured aneurysms were excluded. Rates of endoleaks and reintervention at periprocedural and long-term follow-up timepoints (9-22 mo) were analyzed in grafts 32 mm or larger (LG) and were compared to those smaller than 32 mm (small diameter graft).

RESULTS

A total of 693 patients (22.8% LG) were identified. Overall, demographic variables were comparable except LG exhibited a more frequent history of coronary artery disease (32.9% versus 25.4%, P = 0.037). There were no significant differences in the rates of endoleak at procedural completion. Overall survival at 5 y was no different. The rate of reintervention at 1 y was also no different (log-rank P = 0.86).

CONCLUSIONS

While graft size appears to have an association with outcomes in infrarenal aneurysm repair, the same does not appear to be true for fEVAR. Further studies should evaluate the long-term outcomes associated with LG which could alter the approach to repair of AAA with large neck diameters traditionally treated with standard infrarenal EVAR.

CIRSE Standards of Practice on Management of Endoleaks Following Endovascular Aneurysm Repair

BACKGROUND

Endoleaks represent the most common complication after EVAR. Some types are associated with ongoing risk of aneurysm rupture and necessitate long-term surveillance and secondary interventions.

PURPOSE

This document, as with all CIRSE Standards of Practice documents, will recommend a reasonable approach to best practices of managing endoleaks. This will include imaging diagnosis, surveillance, indications for intervention, endovascular treatments and their outcomes. Our purpose is to provide recommendations based on up-to-date evidence, updating the guidelines previously published on this topic in 2013.

METHODS

The writing group was established by the CIRSE Standards of Practice Committee and consisted of clinicians with internationally recognised expertise in endoleak management. The writing group reviewed the existing literature performing a pragmatic evidence search using PubMed to select publications in English and relating to human subjects up to 2023. The final recommendations were formulated through consensus.

RESULTS

Endoleaks may compromise durability of the aortic repair, and long-term imaging surveillance is necessary for early detection and correct classification to guide potential re-intervention. The majority of endoleaks that require treatment can be managed using endovascular techniques. This Standards of Practice document provides up-to-date recommendations for the safe management of endoleaks.

Large Fenestrations Versus Scallops for the SMA During Fenestrated EVAR: Does it Matter?

OBJECTIVE

FEVAR is an established customized treatment for aortic aneurysms with three current commercially available configurations for the superior mesenteric artery (SMA) - a single-wide scallop, large fenestration, or small fenestration, with the scallop or large fenestration most utilized. Outcomes comparing SMA single-wide scallops to large fenestrations with the ZFEN device are scarce. As large fenestrations have the benefit of extending the proximal seal zone compared to scalloped configurations, we sought to determine the differences in seal zone and sac regression outcomes between the two SMA configurations.

METHODS

We retrospectively reviewed our prospectively maintained complex EVAR database and included all patients treated with the Cook ZFEN device with an SMA scallop or large fenestration configuration at its most proximal build. All first post-operative CT scans (1-30 days) were analyzed on TeraRecon to determine precise proximal seal zone lengths, and standard follow-up anatomic and clinical metrics were tabulated.

RESULTS

A total of 234 consecutive ZFEN patients from 2012-2021 were reviewed, and 137 had either a scallop or large fenestration for the SMA as the proximal-most configuration (72 scallops and 65 large fenestrations) with imaging available for analysis. Mean follow-up was 35 months. Mean proximal seal zone length was 19.5±7.9 mm for scallop vs 41.7±14.4 mm for large fenestration groups (P<.001). There was no difference in sac regression between scallop and large fenestration at one year (10.1±10.9 mm vs 11.0±12.1, P = 0.63). Overall, 30-day mortality (1.3% vs 2.5%, P=.51) and all-cause three-year mortality (72.5% vs 81.7%, P=.77) were not significantly different. Reinterventions within 30 days were primarily secondary to renal artery branch occlusions, with only one patient in the scallop group requiring reintervention for an SMA branch occlusion.

CONCLUSIONS

Despite attaining longer proximal seal lengths, large SMA fenestrations were not associated with a difference in sac regression compared to scalloped SMA configurations at one-year follow up. There were no significant differences in reinterventions or overall long-term survival between the two SMA strategies.

Patient-specific changes in aortic hemodynamics is associated with thrombotic risk after fenestrated endovascular aneurysm repair with large diameter endografts

Background

The durability of fenestrated endovascular aneurysm repair (fEVAR) has been threatened by thrombotic complications. In the present study, we used patient-specific computational fluid dynamic (CFD) simulation to investigate the effect of the endograft diameter on hemodynamics after fEVAR and explore the hypothesis that diameter-dependent alterations in aortic hemodynamics can predict for thrombotic events.

Methods

A single-institutional retrospective study was performed of patients who had undergone fEVAR for juxtarenal aortic aneurysms. The patients were stratified into large diameter (34-36 mm) and small diameter (24-26 mm) endograft groups. Patient-specific CFD simulations were performed using three-dimensional paravisceral aortic models created from computed tomographic images with allometrically scaled boundary conditions. Aortic time-averaged wall shear stress (TAWSS) and residence time (RT) were computed and correlated with future thrombotic complications (eg, renal stent occlusion, development of significant intraluminal graft thrombus).

Results

A total of 36 patients (14 with a small endograft and 22 with a large endograft) were included in the present study. The patients treated with large endografts had experienced a higher incidence of thrombotic complications compared with small endografts (45.5% vs 7.1%; P = .016). Large endografts were associated with a lower postoperative aortic TAWSS (1.45 ± 0.76 dynes/cm² vs 3.16 ± 1.24 dynes/cm²; P < .001) and longer aortic RT (0.78 ± 0.30 second vs 0.34 ± 0.08 second; P < .001). In the large endograft group, a reduction >0.39 dynes/cm² in aortic TAWSS demonstrated discriminatory power for thrombotic complications (area under the receiver operating characteristic curve, 0.77). An increased aortic RT of ≥0.05 second had similar accuracy for predicting thrombotic complications (area under the receiver operating characteristic curve, 0.78). The odds of thrombotic complications were significantly higher if patients had met the hemodynamic threshold changes in aortic TAWSS (odds ratio, 7.0; 95% confidence interval, 1.1-45.9) and RT (odds ratio, 8.0; 95% confidence interval, 1.13-56.8).

Conclusions

Patient-specific CFD simulation of fEVAR in juxtarenal aortic aneurysms demonstrated significant endograft diameter-dependent differences in aortic hemodynamics. A postoperative reduction in TAWSS and an increased RT correlated with future thrombotic events after large-diameter endograft implantation. Patient-specific simulation of hemodynamics provides a novel method for thrombotic risk stratification after fEVAR.

The durability of fenestrated endovascular aneurysm repair (fEVAR) has been threatened by thrombotic complications. Using patient-specific computational flow simulation, the present retrospective study of 36 patients with juxtarenal aortic aneurysms treated with fEVAR identified several endograft diameter-dependent changes in aortic hemodynamics associated with thrombotic complications. A postoperative reduction in aortic wall shear stress and increased particle residence time correlated with the development of intraluminal graft thrombus and renal stent occlusion in patients treated with large diameter (>34 mm) endografts. These computationally estimated hemodynamic parameters could provide a novel method for patient-specific risk stratification for adverse events after fEVAR.