Mid-term Results of the Anaconda Fenestrated Stent-Graft Proximal Sealing System in the Exclusion of Complex Abdominal Aortic Aneurysms

Abstract

Context:

Mid-term data on the Anaconda fenestrated stent-graft remain scarce in the literature.

Objective:

The aim of this study was to evaluate the efficacy and durability of its Z-stent-free proximal sealing system.

Methods:

All consecutive patients treated between January 2018 and May 2023 with the Anaconda Fenestrated stent-graft (Vascutek/Terumo, Scotland, UK) for complex abdominal aortic aneurysm (AAA) were retrospectively included in this monocentric study. The primary outcome was the occurrence of type Ia endoleak (EL). The secondary outcome was the evolution of the proximal sealing zone (PSZ), defined as proximal neck dilatation (PND) ≥3 mm, stent-graft migration (>10 mm), or the need for PSZ-related reintervention. Effective oversizing (OS) was calculated from the nominal stent-graft diameter and the mean aortic diameter at the PNR level on postoperative computed angiography (CT) angiography.

Results:

A total of 111 patients were included (mean age 72±7.6 years, 86% male) with 69 juxta renal aneurysms (62.2%), 23 para-renal aneurysms (20.7%), and 19 proximal EL after EVAR (17.1%). The mean follow-up was 28.1±16.2 months. No primary type Ia EL was observed at discharge. During follow-up, 1 patient (<1%) developed a secondary type Ia EL, which was successfully managed with the placement of an aortic cuff. The PND was observed in 40 patients (36%), while significant stent-graft migration was observed in 1 patient (0.9%) without any impact on proximal sealing or bridging-stents. Effective OS was the only independent predictor of PND in the multivariable analysis (odds ratio [OR]=1.193; 95% confidence interval [CI]= 1.104-1.288; p<0.001). Seven patients (6.3%) underwent prophylactic PSZ-related reintervention, at a mean interval of 26.4±16.9 months following the index procedure, to prevent the occurrence of a type Ia EL.

Conclusion:

The proximal sealing system of the Anaconda fenestrated stent-graft’s demonstrates encouraging mid-term performance, with a low incidence of type Ia EL observed over more than 2 years of follow-up. The PND related to stent-graft OS is common but generally stabilizes after the first year. Beyond this point, any progression should be attributed to the underlying aortic disease. In such cases, proximal extension of the sealing zone can be performed with satisfactory outcomes.

Clinical Impact

This study provides the first dedicated mid-term evaluation of the proximal sealing system of the Anaconda® fenestrated stent-graft in complex abdominal aortic aneurysms. When implanted in a healthy supraceliac landing zone with adequate effective oversizing, the device offers durable proximal sealing with a low incidence of type Ia endoleak. These findings support confident use of the Anaconda® platform in challenging anatomies, while emphasizing the importance of careful deployment to avoid use of the repositioning system and the associated risk of ring tilting. The study also highlights that early proximal neck dilatation is common but usually stabilizes, justifying tailored surveillance and allowing prophylactic proximal extension when necessary.

Keywords

complex aortic abdominal aneurysm fenestrated stent-graft Anaconda proximal endoleak proximal landing zone proximal sealing proximal neck dilatation anchoring stent-graft migration

Introduction

Fenestrated endovascular aneurysm repair (FEVAR) enables minimally invasive treatment of increasingly complex aortic aneurysms when performed by experienced vascular surgeons.^1–3

For over 2 decades, the Zenith Fenestrated stent-graft (Cook Medical, Bloomington, Indiana) has been widely used worldwide, demonstrating excellent long-term outcomes.^4–8 Its proximal anchorage relies on one or, more commonly, 2 Z-shaped stents, providing circumferential and extended apposition to the aortic wall above the celiac artery (CA). The stent-graft body, entirely supported by long Z-shaped steel stents, ensures strong longitudinal stability but limits flexibility, thereby reducing conformability.⁹ As a result, treating patients with highly angulated aorto-iliac anatomy can be particularly challenging with the Zenith Fenestrated platform.

The unsupported body of the Anaconda fenestrated stent-graft (Vascutek/Terumo) may facilitate the treatment of patients with challenging aorto-iliac anatomy. A distinguishing feature of this device is its proximal sealing system, which relies on 2 proximal nitinol rings (PNRs) equipped with 4 hooks, instead of conventional Z-stents. This configuration has raised skepticism among experts, as the proximal sealing zone (PSZ) is both shorter and situated closer to the celiac fenestration, potentially complicating secondary proximal extension in the event of aortic wall degeneration. Furthermore, the absence of longitudinal support may result in tilting of the stent-graft during deployment or repositioning. In such cases, the effective oversizing (OS) may be significantly lower than the planned OS determined during preoperative planning. Given the current lack of medium- and long-term outcome data, the reliability of the Anaconda proximal sealing system remains to be confirmed.^10,11

The objective of this study was to evaluate the efficacy and mid-term durability of the proximal sealing system of the Anaconda fenestrated stent-graft for the exclusion of complex abdominal aortic aneurysms (AAAs).

Materials and Methods

Preoperative Planning and Strategy

Based on expert experience with FEVAR procedures reported in the literature, supraceliac anchoring was systematically preferred to ensure durable proximal sealing.^8,12,13 In addition, the maximum number of target vessels (TVs) was preserved, and the CA, when patent, was systematically incorporated via fenestration. Consequently, stent-grafts with augmented proximal ring designs or with fenestrations located between the 2 PNRs were avoided to maximize the available sealing length above the first bridging-stent—limited to 30 mm with the Anaconda platform—and to maintain the possibility of future proximal extension, if required in cases of late neck degeneration.

All computed tomography angiography (CTA) measurements were performed using Endosize (Therenva SAS, Rennes, France), a dedicated radiological software providing centerline extraction. The proximal landing zone (PLZ), defined 30 mm above the CA, was systematically analyzed to ensure stent-graft anchoring within a healthy segment of aorta.¹³ In case of moderate to severe mural thrombus—indicative of a diseased aorta at risk of future dilatation—an Anaconda stent-graft was deployed within an aortic cuff (Gore, W. L. Gore & Associates or Medtronic Vascular, Santa Rosa, California) during the same procedure to secure proximal fixation and preserve the option of proximal extension if needed.¹³ The PLZ diameter was measured using multiplanar reconstruction (MPR). In cases where the PLZ exceeded 32 mm, a short tapered thoracic endograft (Bolton Relay, Terumo Aortic) was previously implanted to achieve satisfactory OS, given the maximum Anaconda diameter is 36 mm. Planned OS, expressed as a percentage, was calculated from the preoperative CTA as follows: (nominal stent-graft diameter−mean aortic diameter at PLZ)/mean aortic diameter at PLZ (Figure 1).

Selection of Patients

All patients who underwent treatment with the Anaconda fenestrated stent-graft (Vascutek/Terumo) for complex AAAs or for post-EVAR type Ia endoleaks (ELs), and who were deemed unfit for open surgical repair, between January 2018 and May 2023, were retrospectively included. To specifically evaluate the durability of the proximal sealing system, only cases in which the Anaconda stent-graft was implanted in the native aorta were analyzed.

Surgical Procedure

All procedures were performed under general anesthesia in a hybrid operating room equipped with image fusion technology (ARTIS Pheno, Siemens Healthineers, Erlangen, Germany), by a single experienced vascular surgeon. Vascular access was primarily percutaneous via the common femoral arteries; in cases of challenging catheterization or TV stenting, percutaneous axillary access was used as an alternative. Unfractionated heparin was administered at 100 IU/kg, with additional doses to maintain an activated clotting time between 200 and 250 seconds. The TVs were catheterized and stented sequentially, immediately following cannulation. The institutional protocol for spinal cord protection does not include prophylactic cerebrospinal fluid (CSF) drainage. Instead, intraoperative management emphasizes strict control of blood pressure, hemoglobin levels, glycemia, and oxygenation. At the end of the procedure, protamine is systematically administered to reverse anticoagulation and facilitate CSF drain placement if required. Patients are awakened on the operating table for immediate neurological assessment. If necessary, CSF drainage is promptly performed, followed by urgent imaging to rule out postoperative bleeding, which could compromise hemodynamic stability or be worsened by the elevated postoperative blood pressure targets used to optimize spinal cord perfusion.

Follow-up and Imaging Measurements

All patients underwent CTA prior to hospital discharge to rule out procedural complications, particularly type Ia EL. Aortic diameters measured on this examination served as the reference for subsequent follow-up assessments. At hospital discharge, dual antiplatelet therapy was prescribed for 3 months, followed by lifelong single antiplatelet therapy according to the patient’s initial treatment.

Follow-up CTA was performed at 1, 6, and 12 months postoperatively, and annually thereafter. At each time point, the presence of a proximal EL was systematically evaluated. To assess the evolution of the PSZ, the mean aortic diameter at the level of the first PNR was measured using MPR (Figure 2A). Changes in aortic diameter were calculated as the difference between the last available CTA and the first postoperative CTA. According to the latest reporting standards, an increase in aortic diameter ≥3 mm was considered indicative of significant proximal neck dilatation (PND).¹³ All follow-up scans of patients with significant PND were reviewed to analyze proximal neck remodeling over time. Stabilization of the proximal neck was defined as a variation in mean aortic diameter at the PNR level <1 mm across consecutive follow-up CTAs, accounting for expected measurement variability between examinations. In addition, the level of proximal stent-graft anchorage was assessed by measuring the distance between the top of the endoprosthesis and the upper edge of the first fenestration (Figure 2B). Significant stent-graft migration was defined as a >10 mm difference between the postoperative and the last follow-up CTA.^13,14 In such cases, the mean aortic diameter at the initial anchoring site was reassessed to identify potential PND responsible for the migration.

To assess the reproducibility of the radiological measurements, a second blinded evaluation was conducted on a random sample of 15 patients (13.5% of the cohort) by the same trained physician. Intra-observer agreement was assessed using the intraclass correlation coefficient (ICC). Finally, the effective OS was calculated on the discharge CTA based on the constrained stent-graft diameter within the proximal neck as follows: (nominal stent-graft diameter−mean aortic diameter at first PNR)/mean aortic diameter at first PNR (Figure 2A).

Outcomes

The primary outcome was the occurrence of a proximal EL during follow-up.

Secondary outcome was PSZ evolution, defined as significant PND, stent-graft migration, or the need for PSZ-related reintervention.

Ethics

This study was conducted in accordance with the Declaration of Helsinki. The protocol was approved by the institutional ethics committee (approval number: 21_445).

Statistics

Continuous variables are reported as mean (± standard deviation) or median [interquartile range, IQR], as appropriate. Categorical variables are presented as number (proportion). Survival analyses were conducted using the Kaplan-Meier method. Univariate analyses were performed to compare subgroups and to identify potential predictive factors. Continuous variables were assessed for normality using the Shapiro-Wilk test and compared using either the unpaired Student’s t-test or the Mann-Whitney U test, as appropriate. Categorical variables were analyzed using the chi-square test or Fisher’s exact test. Variables with p-values<0.20 in univariate analysis or considered clinically relevant were included in a multivariable logistic regression model. All statistical analyses were performed using XLSTAT.2024.3.0 (Addinsoft, Paris, France).

Results

Population

A total of 151 patients underwent implantation of an Anaconda fenestrated stent-graft during the study period, as illustrated in Figure 3. Of these, 111 patients were included in the final analysis. Demographic and anatomical characteristics of the study population and treated aneurysms are summarized in Table 1.

Table 1.

Demographic Data and Anatomical Characteristics of AAA in Analyzed Patients.

	FEVAR (N=111)
Age, mean (±SD)	72.1 (7.6)
Male sex, n (%)	95 (86)
Hypertension, n (%)	82 (74)
Diabetes, n (%)	17 (15)
Dyslipidemia, n (%)	72 (65)
Smoker, n (%)	43 (16)
Coronary disease, n (%)	45 (41)
Stroke history, n (%)	14 (13)
COPD, n (%)	31 (28)
GFR (mL/min/m²), median [IQR]	74 [59-89]
ASA class, n (%)	—
II	18 (16)
III	90 (81)
IV	3 (3)
Type of AAAs	—
Type Ia EL post-EVAR, n (%)	19 (17)
Juxta renal AAA, n (%)	69 (62)
Para renal AAA, n (%)	23 (21)
Maximal aortic diameter, mm, mean (±SD)	59.4 (9.9)
Proximal neck aortic diameter; mm, mean (±SD)	28.1 (2.4)

Abbreviations: FEVAR, fenestrated endovascular aortic repair; COPD, chronic obstructive pulmonary disease; GFR, glomerular filtration rate; ASA, American Society of Anesthesiology; IQR, interquartile range; SD, standard deviation; AAA, abdominal aortic aneurysm; EL, endoleak; PLZ, proximal landing zone.

Procedural Data and Early Outcomes

Perioperative data and stent-graft characteristics of the analyzed patients are summarized in Table 2. All patients underwent postoperative CTA prior to hospital discharge, with no primary type Ia EL detected. No PSZ-related reinterventions were required during the index hospitalization.

Table 2.

Perioperative Data of Analyzed Patients

Graft body diameter; mm, mean (±SD)	32.4 (2.3)
Theoretical OS; %, mean (±SD)	15.6 (2.8)
Number of fenestrations, mean (±SD)	3.9 (0.6)
Procedure duration (min), median [IQR]	221 [184-282]
DAP (Gy.cm²), median [IQR]	232 [158-338]
Fluoroscopic time (min), median [IQR]	62 [51-80]
Contrast (ml), median [IQR]	83 [69-116]
Type Ia EL at completion angiography, n (%)	0 (0)
Length of stay (days), median [IQR]	6 [5-8]
ICU admission, n (%)	100 (100)
ICU length of stay (days), median [IQR]	1 [1-1]
Type Ia EL at postoperative CTA, n (%)	0 (0)
Real OS; %, mean (±SD)	15.6 (8.0)
PLZ-related reintervention before discharge, n (%)	0 (0)
Paraplegia, n (%)	0 (0)

Abbreviations: FEVAR, fenestrated endovascular aortic repair; DAP, dose area product; ICU, intensive care unit; IQR, interquartile range; OS, oversizing; EL, endoleak; CTA, computed tomography angiography; PLZ, proximal landing zone.

Among the 151 patients treated during the study period, the technical success rate was 98.7%, with 1 case of unsuccessful TV stenting and 1 perioperative TV thrombosis. Procedure-related mortality was 3.3%, and the overall major adverse event rate was 10.6%, as detailed in Supplemental Table 1.

Follow-up

The mean CT follow-up was 28.1±16.2 months (range=6-68 months). A total of 50 reinterventions related to the fenestrated stent-graft were performed in 34 patients (30.6%) (Supplemental Table 2). Aneurysm sac diameter decreased in 36 patients (32.4%), remained stable in 57 (51.3%), and increased in 18 (16.2%).

Among the 151 patients treated during the study period, the overall mortality rate was 13.2%. This included 5 procedure-related deaths (3.3%, within 1 month), 5 early deaths (2.6%, 1-6 months), and 10 mid-term deaths (7.3%, >6 months). Among the 15 patients who died during follow-up, causes of death were cardiovascular (n=5), respiratory failure (n=4, including 2 related to COVID-19), malignancy (n=2), and stroke (n=1). No cause could be identified in the remaining 3 patients. Of these, 2 had unremarkable CTA findings with stable aneurysm sacs within 6 months of death, while the third showed sac regression on a CTA performed 10 months prior to death. The Kaplan-Meier survival estimates at 1, 2, and 3 years were 92.5%, 87.4%, and 83.0%, respectively. No aneurysm-related deaths were observed.

Proximal Endoleak

One patient (0.9%) developed a secondary type Ia EL at 6 months of follow-up. In this case, although the planned OS was 11%, postoperative CTA revealed an effective OS of only 3.5%, attributed to proximal tilting of the endograft after recapture and repositioning. The EL was successfully treated by placement of a proximal aortic extension under local anesthesia, with no evidence of type Ia or type IIIa EL at 20-month follow-up.

Proximal Neck Evolution

The ICC was 0.89 for the mean aortic diameter at the PLZ and 0.86 at the PNR. Significant PND was observed in 40 patients (36%) during follow-up, with a mean increase of 4.6±1.1 mm. In this subgroup, the mean diameter enlargement was 4.4±1.6 mm, 4.5±1.1 mm, and 4.7±1.3 mm at 1-, 2-, 3-years follow-up, respectively. Among these patients, 32 (78%) experienced significant dilation within the first year, followed by stabilization. Of the 8 patients with continued dilation beyond the first year, 4 eventually stabilized after 2 years of follow-up (40- and 64-month follow-up), and 1 patient under 2-year follow-up is being monitored without current indication for reintervention. Three patients underwent successful PSZ-related reintervention to prevent type Ia EL. Figure 4 illustrates the evolution of the effective-to-planned OS ratio over time in patients with significant PND. No PNR fractures were identified on follow-up imaging.

The mean effective OS was significantly higher in patients who developed PND compared to those who did not (20.8±6.8% vs.12.6±6.8%, p<0.001). No significant differences were observed between the 2 groups with regarding age (p=0.40), sex (p=0.21), aneurysm type (p=0.19), maximum aortic diameter (p=0.086), or PLZ diameter (p=0.87). In multivariable analysis—including effective OS, aneurysm type, maximum aortic diameter, and PSZ diameter—effective OS was the only independent predictor of PND occurrence (odds ratio [OR]=1.193; 95% confidence interval CI=1.104–1.288; p < 0.001). Furthermore, PND had no significant impact on TV outcomes: comparison of TV occlusion rates (2/154 vs 1/281) and reinterventions for type III EL (7/154 vs 9/281) showed no statistically significant differences.

Stent-graft Migration

The ICC for the level of proximal stent-graft fixation was 0.82. Stent-graft migration was observed in 1 patient (0.9%), with no evidence of significant PND at the initial PSZ. This patient had undergone treatment for a para-renal AAA, with a planned OS of 13.3%. The discharge CTA revealed an effective OS of only 2.4%, attributed to tilting of the PNRs. However, the migration had no impact on TV patency or fenestration sealing during follow-up.

Proximal Sealing Zone-Related Reintervention

Seven patients (6.3%) required proximal aortic extension at a mean interval of 26.4±16.9 months. Indications and procedural details relating to these PSZ-related reinterventions are presented in Table 3. Among them, 1 patient underwent thoracic endovascular aortic repair (TEVAR) at the 2-year follow-up due to significant progression of the PSZ and of the descending thoracic aorta. One procedural complication was recorded: compression of a superior mesenteric artery (SMA) bridging-stent, which was successfully managed by re-flaring the stent. Follow-up CTA of all reoperated patients demonstrated favorable outcomes, with no type Ia or IIIa ELs and no complications involving the CA bridging-stent. The Kaplan-Meier estimates for freedom from type Ia EL and PLZ-related reintervention are shown in Figure 5. Univariate analyses revealed no significant differences between the 2 subgroups for the variables assessed.

Table 3.

Data Regarding Patients Who Underwent PLZ-Related Reintervention.

AAA	Indications	At (months)	Stent-graft	Anesthesia	P-O LOS (days)	TS^a	Complications^b
PR	Significant PND	23	TEVAR	General	2	Yes	None
JR	Loss of proximal fixation	18	Cuff	Local	3	Yes	AKI
JR	Significant PND	58	Cuff	Local	1	Yes	None
JR	Significant PND	29	Cuff	Local	1	Yes	None
JR	Preventive (associated to endoaneurysmorrhaphy)	36	Cuff x2	General (laparotomy)	6	Yes	SMA BS crushing
JR	Loss of proximal fixation	10	Cuff x2	Local	1	Yes	None
JR	Loss of proximal fixation	10	Cuff	Local	2	Yes	None

Loss of proximal fixation: defined as at least 1 of the proximal hooks no longer in contact with the aortic wall, raising concerns about proximal EL (with the subsequent risk of aortic rupture) or tilting of the stent-graft body (with the risk of aortic thrombosis).

Abbreviations: AAA, abdominal aortic aneurysm; P-O LOS, postoperative length of stay; TS, technical success; PR, para-renal aneurysm; JR, juxta renal aneurysm; PNR, proximal nitinol rings; PND, aortic neck dilatation; AKI, acute kidney injury; SMA, superior mesenteric artery; BS, bridging-stent.

Defined as successful placement of the proximal aortic component, without CA bridging-stent crushing or any bridging-stent disconnection and with circumferential overlap of the Anaconda stent-graft PNRs.

Included any surgical or medical complication prolonging hospital stay.

Discussion

To our knowledge, this is the first study specifically designed to assess the performance of the proximal sealing system of the Anaconda fenestrated endograft. In a large cohort (N>100) of patients treated for complex AAAs, the sealing system demonstrated durable efficacy, with a low incidence (<1%) of type Ia ELs at a mean follow-up exceeding 2 years. When required, secondary proximal aortic extension proved to be an effective approach for the treatment or prevention of late proximal ELs.

The development of endovascular techniques over recent decades has progressively established endovascular aortic repair as the treatment of choice, including for complex aortic aneurysms.^1,15 In anatomically suitable cases, custom-made fenestrated stent-grafts have emerged as a compelling alternative to open repair, offering significant reductions in perioperative morbidity and mortality.¹⁶ Several years after the introduction of the Zenith fenestrated stent-graft, the Anaconda device became available, incorporating specific design features that may expand patient eligibility or simplify the FEVAR procedure, as described by Colgan et al.¹⁷ However, in the absence of long Z-shaped proximal steel stents and published long-term outcomes, the reliability of its proximal sealing system remains uncertain.^18,19

Contrary to previous reports on the Anaconda device, no primary type Ia ELs were observed in this cohort. This result was objectively confirmed by the systematic use of postoperative CT angiography in all patients prior to discharge, ensuring reliable detection of any early proximal complications.^17,18,20,21 Blankensteijn et al¹⁸ reported the highest rate of primary proximal EL (11.7%), all of which resolved spontaneously during follow-up. In contrast, no secondary proximal ELs were identified in their study after 16 months of follow-up. First, the validity of type Ia EL reported on intraoperative control angiography in several studies is questionable. The risk of misinterpretation with type II or TV-related type III EL appears considerable. Moreover, given the unsupported design of the stent-graft body, contrast may occasionally be observed around the device when lumbar arteries originate immediately downstream of the PNRs. Therefore, meticulous analysis of both preoperative and postoperative CT angiography is crucial to avoid misdiagnosing a type Ia EL. Moreover, the lower incidence observed in this series may also be attributable to the systematic use of supraceliac anchoring, a strategy well documented in the literature to reduce the risk of proximal ELs.^12,22,23 Thus, the mean number of fenestrations in the present cohort was 3.9 per patient, compared with 2.3 per patient in the study by Blankensteijn et al.¹⁸ In addition, the stent-graft repositioning system was used in 68% of cases in that study. Over time, this feature has been progressively abandoned in clinical practice, in favor of a more meticulous initial deployment, aiming to optimize both the level and rotational orientation of the stent-graft. Owing to the unsupported design of the stent-graft body, vertical repositioning using the recapture system may lead to tilting of the PNRs, potentially reducing effective OS and compromising proximal anchorage. This may increase the risk of type Ia EL or even aortic occlusion. Moreover, rotational adjustments are difficult to transmit precisely to the PNRs, potentially causing torsion of the stent-graft body and leading to complications such as aortic occlusion or TV instability.

Early type Ia EL has also been reported in the literature with the Cook Zenith fenestrated endograft, with rates ranging from 1.2 to 2.5% depending on the series.^7,12 In the study by Haulon et al,⁷ as in the present series, systematic postoperative CT angiography was performed in all patients before discharge. One type Ia EL resolved spontaneously within 3 months, while another persistent case was attributed to a suprarenal fixation point (SMA scallop). Furthermore, O’Callaghan et al¹² reported a significantly higher rate of early type Ia ELs in cases of infraceliac anchoring.

During follow-up, 1 patient (<1%) developed a secondary type Ia EL and another experienced stent-graft migration (<1%), both events likely related to insufficient effective OS (3.5% and 2.4%, respectively). These complications may have resulted from stent-graft tilting associated with the repositioning system frequently used during the early phase of clinical experience with this device. It is also important to consider patients who underwent prophylactic reintervention, as the occurrence of a proximal EL cannot be definitively ruled out in the absence of such intervention (3 patients with loss of proximal fixation and 1 prior to endoaneurysmorrhaphy). Assuming maximum bias, the rate of secondary type Ia ELs in this cohort would reach 4.5% in the worst-case scenario. This figure remains consistent with previously published data on the Anaconda device, where reported incidences range from 1% to 5% depending on the series.^11,20,21 By comparison, the excellent outcomes reported with the Cook platform by Haulon et al⁷ and Oderich et al²² (0% and 0.8% secondary type Ia ELs, respectively) should be interpreted in light of the relatively short follow-up durations in both studies (10 and 9.2 months, respectively). In contrast, Mastracci et al⁸ reported a 3% rate of secondary type Ia ELs and a <1% rate of stent-graft migration with a mean follow-up of 8 years. The particularly low rate of proximal EL observed in the present cohort may be attributable to rigorous preoperative assessment of the PLZ, ensuring implantation in a healthy aortic segment. In 14% of juxta renal or para-renal AAA cases, the fenestrated stent-graft was deployed in a previously implanted aortic cuff or short tapered thoracic endograft due to an unsuitable proximal neck.²⁴ Moreover, systematic postoperative CT follow-up was essential for accurate assessment of proximal neck evolution.

Although the absence of high proximal Z-stents does not appear to compromise the medium-term sealing performance of the Anaconda stent-graft, its shorter proximal extension above the CA—compared with the Cook platform—may theoretically lower the risk of spinal cord ischemia. This hypothesis, previously supported by Mastracci et al,⁸ aligns with the absence of spinal cord ischemia reported in this cohort. When necessary, secondary proximal extension has proven to be technically feasible and associated with satisfactory mid-term outcomes.

In this cohort, significant PND was observed in over than one third of patients during follow-up. This dilatation occurred predominantly within the first year and tended to slow or stabilize thereafter. The PSZ-related reinterventions were required in 6.3% of cases. However, this rate would likely be lower today, due to the increased experience acquired throughout the study period. Notably, the 3 patients who underwent early reintervention based solely on the presence of PND would now likely be managed conservatively with close imaging surveillance. Similar observations have been reported by other authors, attributing this early neck expansion to the conformation of the aortic wall to the expansion of the PNRs toward their nominal diameter following Anaconda EVAR.^25–27 Moreover, this phenomenon is not unique to the Anaconda stent-graft proximal sealing system, as similar findings have been reported following both EVAR and FEVAR procedures, irrespective of the device used.^19,28,29 Thus, the early PND observed in this cohort likely reflects the radial force exerted by the PNRs on the aortic wall, which appears proportional to stent-graft OS and was significantly higher in this subgroup. These findings are consistent with those recently reported by Mezzetto et al²⁸ in a meta-analysis including numerous EVAR studies and 4 FEVAR studies—all involving the Cook platform—suggesting a potential association between OS and PND. However, regular CTA surveillance remains essential in the long term to identify any persistent PND beyond the first 12 months, which may indicate progression of the underlying aortic disease. In such cases, apposition of the PNRs to the aortic wall may become insufficient, increasing the risk of rupture due to proximal EL. Moreover, the absence of longitudinal support from proximal Z-stents raises concerns regarding stent-graft stability, with the potential for proximal tilting and subsequent aortic thrombosis. In this series, whenever at least 1 proximal hook failed to contact the aortic wall, proximal aortic extension was systematically performed—either early, in conjunction with insufficient effective OS, or later, in association with significant PND.

Notably, no PNR fractures were observed in this study, despite its specific focus on the proximal sealing system of the Anaconda stent-graft. It is worth noting, however, that the 3 cases reported in the literature occurred in configurations with only 2 renal fenestrations (n=2) or 3 fenestrations including 1 for the SMA located between the 2 PNRs (n=1).^30–32

The main limitation of this study lies in its retrospective design, with the inherent biases associated with such methodology. Nevertheless, the rate of loss to follow-up remained acceptable at approximately 7%. In addition, measurements were limited to the apex of the stent-graft, whereas a staggered evaluation along the supraceliac aorta could have provided a more comprehensive assessment of proximal neck evolution. Finally, the absence of an external core laboratory or a second blinded operator may have introduced a risk of measurement bias. Furthermore, to specifically evaluate the proximal anchoring system of the endoprosthesis, only patients with a healthy supraceliac aortic neck—allowing direct implantation into the native aorta—were included. Although this approach ensured a homogeneous study population, it introduced a selection bias that may limit the generalizability of the findings. Furthermore, all procedures were performed by a single experienced surgeon, which, although ensuring technical consistency, may reduce external validity—particularly in lower-volume centers with varying operator experience. Finally, although the mean follow-up exceeded 2 years, the study provides only mid-term data. Extended follow-up is required to more accurately assess the long-term durability of the Anaconda proximal sealing system and the risk of late proximal neck degeneration or type Ia EL.

Conclusion

The proximal sealing system of the Anaconda fenestrated stent-graft demonstrates encouraging mid-term performance when implanted in the supraceliac aorta, as evidenced by the low incidence of type Ia ELs at a mean follow-up exceeding 2 years. The PND, associated with the radial force of the stent-graft, was frequently observed but generally stabilized after the first year. Beyond this point, progression of the underlying aortic disease, with the risk of proximal EL, should be considered. In such cases, proximal aortic extension was technically feasible, although potential complications—particularly involving bridging-stents—require continued vigilance. Nevertheless, longer-term follow-up is necessary to confirm the sustained durability of the Anaconda proximal sealing system.

Supplemental Material

sj-pdf-1-jet-10.1177_15266028251406781 – Supplemental material for Mid-term Results of the Anaconda Fenestrated Stent-Graft Proximal Sealing System in the Exclusion of Complex Abdominal Aortic Aneurysms

Supplemental material, sj-pdf-1-jet-10.1177_15266028251406781 for Mid-term Results of the Anaconda Fenestrated Stent-Graft Proximal Sealing System in the Exclusion of Complex Abdominal Aortic Aneurysms by Marine Bordet, Alexandre Oliny, Heloise Tessely, Matthieu Arsicot, Nellie Della Schiava and Antoine Millon in Journal of Endovascular Therapy

Supplemental Material

sj-pdf-2-jet-10.1177_15266028251406781 – Supplemental material for Mid-term Results of the Anaconda Fenestrated Stent-Graft Proximal Sealing System in the Exclusion of Complex Abdominal Aortic Aneurysms

Supplemental material, sj-pdf-2-jet-10.1177_15266028251406781 for Mid-term Results of the Anaconda Fenestrated Stent-Graft Proximal Sealing System in the Exclusion of Complex Abdominal Aortic Aneurysms by Marine Bordet, Alexandre Oliny, Heloise Tessely, Matthieu Arsicot, Nellie Della Schiava and Antoine Millon in Journal of Endovascular Therapy

Footnotes

ORCID iDs

Marine Bordet

Alexandre Oliny

Heloise Tessely

Ethical Considerations

This study complied with the Declaration of Helsinki on research ethics. The study protocol was approved by the institutional ethics committee under number 21_445.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

We agree to share our research data.

Supplemental Material

Supplemental material for this article is available online.

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