Failure mode analysis of the Endologix endograft

Type III Endoleak Incidence and Outcomes in Endovascular Aortic Repair: Comparison of Anatomical and Proximal Fixation Devices

PURPOSE

To evaluate the influence of endograft fixation type on the incidence, treatment, and outcomes of type III endoleaks (TIIIELs).

MATERIALS AND METHODS

Abdominal aortic aneurysms (AAAs) treated with bifurcated endografts between 1994 and 2020 were prospectively collected and reviewed. The endograft included were classified as "Anatomical Fixation" (AF) (Powerlink [Endologix] and AFX [Endologix]) or "Proximal Fixation" (PF). The primary outcome was the incidence of TIIIEL over time, stratified by fixation type. Secondary outcomes included between-group comparisons of baseline characteristics, intraoperative details during TIIIEL correction, and survival analysis after TIIIEL diagnosis.

RESULTS

A total of 2065 endovascular aneurysm repairs were performed: 872 (42.2%) with AF and 1193 (57.8%) with PF devices. The estimated incidence of TIIIEL at 1, 5, and 10 years was 0.4%, 4.2%, and 7.3%, and 0.5%, 3.2%, and 4.6% for AF and PF, respectively (p=0.157), and fixation type was not associated with TIIIEL development in the competing risk regression model (p=0.101). The cumulative overall survival rate in patients diagnosed with TIIIEL did not differ significantly between the groups (p=0.077). The rate of recurrent TIIIELs was significantly lower in the AF group (7.1% vs 22.7%; p=0.044); however, no significant difference was found in secondary reintervention between the two groups (11.9% vs 27.3%, p=0.074). Patients with angulated and calcified aortic neck (SHR 3.4, 95% CI 1.2-9.6, p=0.022) and larger aneurysms (SHR 1.2; 95% CI 1.1-1.3; p<0.001) had a higher risk of TIIIEL. Likewise, the use of three or more endograft components increased the risk of TIIIEL by 3.1 times (SHR 3.1; 95% CI 1.7-5.4; p<0.001).

CONCLUSIONS

The occurrence of TIIIELs was not affected by the type of endograft fixation. For larger abdominal aortic aneurysms (AAAs) and aneurysms with angulated and calcified aortic necks, there is a higher likelihood of developing TIIIELs during follow-up, regardless of the endograft type used.

CLINICAL IMPACT

The type of fixation does not influence the incidence of TIII ELs. EVAR in larger AAAs and aneurysms with angulated and calcified aortic necks have a higher risk of developing TIII EL. Moreover, the risk of TIII EL is considerably increased by the use of three or more modular components.

Serious Failure Modes After EVAR Are Device Specific

OBJECTIVES

Type I and III endoleaks following endovascular aneurysm repair (EVAR) can lead to catastrophic events that require major re-interventions. We reviewed our experience with aortic endograft re-interventions for type I and III endoleaks and other serious failures among different devices.

METHODS

We retrospectively reviewed patients with a prior EVAR who underwent open conversion (OC) or major endovascular intervention (MEI) (re-lining, cuff/limb extension, parallel graft) for type I/III endoleaks at our institution from 2002 to 2019. Baseline characteristics, procedural details, re-interventions, and outcomes were collected.

RESULTS

A total of 229 patients (194 men) underwent re-interventions for type I and III endoleaks after EVAR (90 OC, 139 MEI) for devices implanted between 1997 and 2019. Average age at re-intervention was 78±8.5 years. A total of 135 (59%) were implanted at our institution, whereas 93 (41%) were referred. Median time to re-intervention was 4 years with 25% to 75% interquartile range (IQR) of 2.2-6.6 years. There was no significant difference in baseline demographics or type of re-interventions (OC/MEI) between device types. 42/229 (18%) presented with ruptured aneurysms, 20/229 (9%) were symptomatic, whereas the rest presented with asymptomatic radiographic findings. Type 1A endoleak was present in 146/229 (63.8%-72 with proximal migration), type IB in 46/229 (20.1%), type IIIA in 37/229 (16.6%), type IIIB in 15/229 (6.5%), and persistent aneurysm sac growth with no radiographic evidence of an endoleak in 6/229 (2.6%). Devices included most commercial products: AFX, Excluder, AneuRx, Ancure, Endurant, and Zenith. A smaller number of investigational devices accounted for the rest. Type 1A endoleak was the most common indication for re-intervention among all devices except for AFX and ancure devices, proximal migration was a frequent presentation with AneuRx. AFX devices more frequently presented with a type III and ancure devices more frequently presented with a type IB endoleak.

CONCLUSIONS

Serious failure modes after EVAR differ between endografts and occur throughout the follow-up period. This is important to guide targeted interrogation of surveillance studies and follow-up schedules, even for discontinued devices, as well as comparisons between various series and estimation of EVAR failure rates.

CLINICAL IMPACT

Surveillance after EVAR is critical for long term success of the repair, understanding of the differential modes of failure of every graft available is important in the longitudinal evaluation of these endografts. Equally important is the understanding of the modes of failure of legacy endografts that are no longer on the market but still being followed, in order to be able to tailor a surveillance regiemn and the evntual repair if needed.

Device regulation and surveillance in vascular care: Challenges and opportunities

Cardiovascular devices are essential for the treatment of cardiovascular diseases including cerebrovascular, coronary, valvular, congenital, peripheral vascular and arrhythmic diseases. The regulation and surveillance of vascular devices in real-world practice, however, presents challenges during each individual product's life cycle. Four examples illustrate recent challenges and questions regarding safety, appropriate use and efficacy arising from FDA approved devices used in real-world practice. We outline potential pathways wherein providers, regulators and payors could potentially provide high-quality cardiovascular care, identify safety signals, ensure equitable device access, and study potential issues with devices in real-world practice.

Delayed migration due to shortening of the lower part of AFX endograft's main body in angled fusiform abdominal aortic aneurysm

We encountered two fusiform abdominal aortic aneurysm cases with delayed AFX endograft (Endologix Inc) migration >4 years after placement. These cases showed shortening and slight angulation of the main body in the anteroposterior direction. We speculate that the potential mechanism relates to the AFX portion that is easily shortened at the bifurcation of its stent structure. This portion might contribute to delayed migration after slight angulation of the main body. Preoperative three-dimensional computed tomography should be performed from the anteroposterior and lateral views. Although the AFX is useful for narrow bifurcations, one should consider the patient's anatomy before deciding to use an AFX endograft.

Three-Year Safety and Efficacy of the INCRAFT Endograft for Treatment of Abdominal Aortic Aneurysms: Results of the INSIGHT Study

PURPOSE

Preliminary results of the INSIGHT study showed that the low-profile INCRAFT Abdominal Aortic Aneurysm (AAA) Stent-Graft System was safe and effective in the endovascular aneurysm repair (EVAR). This study aimed to assess the durability and the midterm effectiveness of EVAR using the INCRAFT System in the framework of a multicenter, prospective, open-label, post-approval study.

MATERIALS AND METHODS

Between 2015 and 2016, 150 subjects from 23 European centers treated with the INCRAFT System for an infrarenal AAA were included. Clinical and radiologic data were prospectively collected and analyzed using protocol-specified, monitored follow-up clinic visits at 1, 6, and 12 months post-implantation and annually after that. The clinical success at 3 years was determined. Freedom from overall and aneurysm-related mortality, type I endoleak, secondary interventions, and aneurysm sac enlargement through 3 years were evaluated. Kaplan-Meier estimates were used for late outcomes. An independent clinical events committee reviewed all events. The CT (computed tomography) scans through 1 year were reviewed by an independent core laboratory.

RESULTS

The primary clinical success rate at 3 years was 84.0% (126/150). There were no aneurysm-related deaths, endograft migration, or aneurysm-related ruptures through 3 years. Stent fracture was detected in 2 subjects (1.3%) without clinical sequelae. Over 3 years, freedom from overall mortality was 89.4%, freedom from secondary interventions was 80%, and freedom from aneurysm sac enlargement was 96.5%. The 3-year freedom from type IA and IB endoleaks was 93.3% and 98.6%, respectively.

CONCLUSIONS.

In a multicenter real-world study setting, the use of a low-profile INCRAFT device for AAA is associated with sustained clinical success and low rates of reinterventions through 3 years.

CLINICAL IMPACT

Low-profile endografts have broadened the spectrum of patients with anatomic suitability for endovascular repair of abdominal aortic aneurysms (AAA). However, questions remain regarding the durability of the repair. The INSIGHT study evaluated the use of the INCRAFT System in routine real-world clinical practice, including patients with complex anatomies. The treatment was safe and effective. The results showed sustained clinical success over 3 years, with no aneurysm-related deaths or ruptures, and a high rate of intervention-free survival at 3 years. Despite the low-profile design of the endograft, the midterm results demonstrate the durability of AAA repair using the INCRAFT System.ClinicalTrials.gov Identifier: NCT02477111.

Incidence, Long Term Clinical Outcomes, and Risk Factor Analysis of Type III Endoleaks Following Endovascular Repair of Abdominal Aortic Aneurysm

OBJECTIVE

To assess the real world incidence, outcomes, and risk factors of type III endoleaks (TIIIEL) after endovascular aneurysm repair (EVAR).

METHODS

This was a single centre, retrospective, observational, cohort study. All patients with abdominal aortic aneurysms (AAAs) receiving EVAR between 1994 and 2020 were collected prospectively and reviewed. The primary outcome was the cumulative incidence and impact on survival of TIIIELs, either defined as disconnections of modular graft components (TIIIaEL) or fabric defects (TIIIbEL). Secondary outcomes included risk factor analysis evaluating baseline morphological and stent graft details, as well as a comparison of TIIIaEL and TIIIbEL.

RESULTS

In total, 2 565 EVARs were performed and 95 (3.7%) TIIIELs were diagnosed at a median interval of 49.5 months (interquartile range [IQR] 19.4, 67.6). Estimated TIIIEL incidence at five years was 6.8%, 2.2%, and 3.6% for first and second generation, third and fourth generation, and fifth and sixth generation, respectively. The survival rate in patients without any high flow endoleak was 88.0%, 67.9%, 56.9%, and 52.1%, while in TIIIEL patients it was 98.6%, 77.2%, 49.8%, and 32.3% at one, five, 10, and 15 years, respectively (p = .77). The distribution of TIIIaEL and TIIIbEL was 70.5% and 29.5%, respectively. TIIIbEL received a higher rate of open treatment (28.6% vs. 7.5%; p = .005) and device or procedure related re-interventions (35.7% vs. 13.4%; p = .013). Fourteen (15.4%) recurrent TIIIELs were diagnosed at a median of 16.8 months (IQR 7.6, 32.1). Old generation endografts (hazard ratio [HR] 2.1, 95% confidence interval [CI] 1.3 - 3.4; p = .002) and non-proprietary extensions (HR 3.6, 95% CI 1.9 - 6.8; p < .001), and angulated and calcified aneurysm neck (HR 3.6, 95% CI 1.2 - 10.6; p = .017) were risk factors for TIIIEL. Every 10 mm maximum AAA diameter increase presented a 1.4 fold higher risk of TIIIEL.

CONCLUSION

TIIIEL is a severe condition that is often fatal if left untreated. Old endografts, the implantation of non-proprietary extensions, large AAAs, and angulated and calcified necks are risk factors for TIIIEL that require careful follow up due to the high rate of recurrence.

Side-by-side deployment of gore excluder legs at a narrow terminal aorta for endovascular aneurysm repair

PURPOSE

A narrow terminal aorta is a risk factor for endograft occlusion after endovascular aneurysm repair. To minimize limb complications, we used Gore Excluder legs positioned side-by-side at the terminal aorta. We investigated the outcomes of our strategy for endovascular aneurysm repair in patients with a narrow terminal aorta.

METHODS

We enrolled 61 patients who underwent endovascular aneurysm repair with a narrow terminal aorta (defined as < 18 mm in diameter) from April 2013 to October 2021. The standard procedure involves complete treatment with the Gore Excluder device. When other types of main body endografts were used, they were deployed proximal to the terminal aorta, and we used the Gore Excluder leg device in the bilateral limbs. Postoperatively, the intraluminal diameter of the legs at the terminal aorta was measured to assess the configuration.

RESULTS

During the follow-up period (mean: 2.7 ± 2.0 years), there were no aorta-related deaths, endograft occlusions, or leg-related re-interventions. There were no significant differences between the pre- and postoperative ankle-brachial pressure index values in the dominant and non-dominant legs (p = 0.44 and p = 0.17, respectively). Postoperatively, the mean difference rate (defined as [dominant leg diameter-non-dominant leg diameter]/terminal aorta diameter) was 7.5 ± 7.1%. The difference rate was not significantly correlated with the terminal aortic diameter, calcification thickness, or circumferential calcification (r = 0.16, p = 0.22; r = 0.07, p = 0.59; and r = - 0.07, p = 0.61, respectively).

CONCLUSIONS

Side-by-side deployment of Gore Excluder legs produces acceptable outcomes for endovascular aneurysm repair with a narrow terminal aorta. The endograft expansion at the terminal aorta is tolerable without influencing calcification distribution.

Five-Year Results of the LEOPARD Trial of Commercially Available Endografts

OBJECTIVE

The LEOPARD (Looking at EVAR Outcomes by Primary Analysis of Randomized Data) trial is a randomized controlled trial (RCT) comparing the outcomes of endovascular aneurysm repair (EVAR) using commercially available devices in a real-world population.

METHODS

A prospective, randomized, multi-center trial was performed to compare the anatomically fixated (AF) AFX/AFX2 endograft system (Endologix, Irvine, CA) to endografts with proximal fixation (PF) (Cook Medical Zenith Flex, Bloomington, IN; Gore Excluder, Flagstaff, AZ; and Medtronic Endurant II, Minneapolis, MN) in patients with infrarenal abdominal aortic aneurysms (AAA). The primary endpoint was freedom from aneurysm-related complications (ARC), a composite endpoint consisting of perioperative death (≤30 days), aneurysm rupture, conversion to open surgical repair, post-operative endoleaks, endograft migration (≥10 mm), aneurysm enlargement (≥5mm), endograft limb occlusion, and the device- or aneurysm-related reintervention.

RESULTS

The study population was 455 patients enrolled at 56 US centers: 235 patients were treated with anatomically fixated devices and 220 with proximal fixation devices. The primary endpoint supported noninferiority of the AF cohort at 1 year. The 5-year freedom from aneurysm-related complications Kaplan Meier estimates were 63.8% for anatomically fixated patients and 55.5% for proximal fixation patients (p=0.10). Kaplan-Meier estimates for freedom from aneurysm-related mortality (ARM) were 98.7% and 97.0% in the anatomically fixated group and 99.5% and 98.5% in the proximal fixation group at 1 and 5 years. There was no difference in aneurysm-related mortality, all-cause mortality, rupture, secondary interventions, and Type I and Type III endoleak between the two cohorts. The Type III endoleak rate at 5-years for the AFX cohort was 1.5% and 0.0% for the comparator cohort (p=0.11). There was a lower type II endoleak rate in the AF group at 5 years (78.8% vs. 68.4%, p=0.037). There were zero open surgical conversions (0.0%) in the anatomically fixated group and four (2.0%) in the proximal fixation group .

CONCLUSION

The 5-year results from the LEOPARD study demonstrated that there was no clinically significant difference in overall aneurysm-related outcomes between patients randomized to the AFX endograft system or commercially available endografts with proximal fixation.

Risk for surgical interventions following endovascular aneurysm repair with Endologix AFX or AFX2 Endovascular AAA Systems compared to other devices

OBJECTIVE

To evaluate the risk for 90-day returns to care and long-term subsequent surgical interventions following primary endovascular aneurysm repair (EVAR) with an Endologix AFX Endovascular AAA System compared to three other high-volume endograft devices.

METHODS

We conducted a matched cohort study using data from an integrated healthcare system's Endovascular Stent Graft Registry. Patients aged ≥18 years who underwent primary EVAR for AAA in the healthcare system from 1/1/2011-12/31/2017 comprised the eligible study sample. The treatment group included patients who received an Endologix AFX or AFX2 device (n=470). Patients who received one of three other high-volume endograft devices used within the healthcare system comprised the eligible comparison group (n=2122). These patients were 2:1 propensity score matched without replacement to patients who received an Endologix device based on a number of patient and procedure characteristics. After the application of matching, conditional logistic regression was used to evaluate the likelihood for 90-day emergency department (ED) visit and readmission. Cause-specific Cox regression was used to evaluate the long-term risk of endoleak, graft revision, secondary reintervention (not including revision), conversion to open repair, and rupture during follow-up. Cox proportional hazards regression was used to evaluate the risk of mortality (overall and aneurysm-related).

RESULTS

The final matched study sample included 470 patients who received an Endologix AFX or AFX2 device and 940 patients who received a different high-volume device. Compared to the other devices, AFX/AFX2 had a higher risk for type III endoleak (hazard ratio [HR]=38.79, 95% confidence interval [CI]=14.51-103.67), revision surgery more than 1-year following the primary EVAR (HR=4.50, 95% CI=3.10-6.54), rupture (HR=6.52, 95% CI=1.73-24.63), and aneurysm-related mortality (HR=2.43, 95% CI=1.32-4.47) was observed with use of AFX/AFX2.

CONCLUSION

In our matched cohort study, patients who received an Endologix AFX System during their primary EVAR had a higher risk for several adverse longitudinal outcomes, as well as aneurysm-related mortality, when compared to patients who received other high-volume devices. Patients who have received these devices should be closely monitored following EVAR.

Late Type III Endoleak after Loss of Component Overlap after EVAR with AFX2 Device: A Case Report

Addressing the high incidence of late type III endoleaks in previous AFX models, Endologix upgraded the device material and updated its recommendation regarding component overlap. However, whether upgraded AFX2 models are safe for endoleaks remains controversial. Here we report a case of a 67-year-old male with an AFX2-implanted abdominal aortic aneurysm experiencing a delayed type IIIa endoleak. Aneurysmal sac enlargement occurred 36 months post-endovascular aneurysm repair (EVAR), with a computed tomography scan at 52 months revealing component overlap loss and a significant type IIIa endoleak. We performed endograft explantation and endoaneurysmal aorto-bi-iliac interposition grafting. Our findings suggest that sufficient component overlap is necessary when using an AFX2 endograft outside the manufacturer's instructions for use to prevent late type IIIa endoleaks. Moreover, patients who undergo EVAR with AFX2 for tortuous large aortic aneurysms should be carefully monitored for conformational changes.

Midterm outcomes of AFX2 endografts used in combination with aortic cuffs

OBJECTIVE

Type III endoleaks after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs) with the Endologix unibody endograft remain a major concern, despite fabric, system, and instructional updates. The purpose of this study was to examine real-world outcomes of repairing AAAs using the current version of the AFX2 main body in combination with an aortic cuff, specifically focusing on type III endoleaks and morphological changes of the endograft.

METHODS

We recruited facilities in Japan that used AFX2 combined with an aortic cuff for at least five cases between April 2017 and March 2018. A total of 175 cases in 24 facilities were analyzed. Patients' background information, including anatomic factors, operative findings, device component variations, and midterm outcomes at 3 years after the EVAR were collected. The data on computed tomography scans from cases registered as types I and III endoleaks and migration from each institute were sent to our department for verification.

RESULTS

The mean patient age was 74.6 ± 8.1 years, and 48 cases (27%) were saccular aneurysms. The mean fusiform and saccular AAA diameters were 50.5 ± 5.8 mm and 43.5 ± 8.9 mm, respectively. No in-hospital deaths occurred. Data at 3 years, including computed tomography images, of 128 cases were analyzed. Overall survival, freedom from aneurysm-related mortality, and freedom from reintervention rates at 3 years were 85.8%, 99.3%, and 87.3%, respectively. There were three, one, and three cases of types I, IIIa, and IIIb endoleaks without sac dilatations, respectively. Among five migration cases, one case of aortic cuff migration presented as a type Ia endoleak, and four cases demonstrated sideways displacement, one of which presented as a type IIIa endoleak. The sac regression and enlargement rates at 3 years were 41.4% and 20.5% in the fusiform group and 44.2% and 16.7% in the saccular group, respectively. The proximal neck diameter slightly increased from 20.8 ± 2.7 mm before the EVAR to 22.2 ± 4.6 mm after the repair.

CONCLUSIONS

Midterm outcomes of the AFX2 used in combination with an aortic cuff were acceptable, considering the rates of types I and III endoleaks. However, there were cases of sideways displacement that could cause future type IIIa endoleaks. When the AFX2 is used in combination with an aortic cuff, close surveillance for endograft deformations and subsequent adverse events, including type III endoleaks, is needed.

One-year safety and effectiveness of the Alto abdominal stent graft in the ELEVATE IDE trial

OBJECTIVE

This study reports the results of a prospective, multicenter trial designed to evaluate the safety and effectiveness of the polymer based Endologix Alto Stent Graft System in treating abdominal aortic aneurysms (AAAs), with sealing 7 mm below the top of the fabric in aortic neck diameters from 16 to 30 mm.

METHODS

Seventy-five patients were treated with Alto devices between March 2017 and February 2018 in 16 centers in the United States for infrarenal AAAs (max diameter ≥5.0 cm in diameter or size increase by 0.5 cm in 6 months or diameter ≥1.5 times the adjacent normal aorta). Patients were followed for 30 days, 6 months, and 1 year by clinical evaluation and computed tomography and abdominal x-ray imaging. Treatment success was defined as technical success and freedom from AAA enlargement, migration, type I or III endoleak, AAA rupture or surgical conversion, stent graft stenosis, occlusion, kink, thromboembolic events, and stent fracture attributable to the device requiring secondary intervention through 12 months. Preoperative characteristics, perioperative variables, follow-up clinical evaluations, and radiographic examination results through the first 1 year were analyzed.

RESULTS

The mean patient age was 73 years, with 93% of patients being male. The 30-day major adverse event rate was 5.3%. At 1 year, the primary endpoint was met with a treatment success rate of 96.7%. Through 1-year post-treatment, all-cause mortality was 4.0%. No AAA-related mortality occurred. AAA enlargement was 1.6%, type I endoleak rate was 1.4%, with 100% freedom from type III endoleaks, device migration, device fracture, stent occlusion, or AAA rupture. The device-related secondary intervention rate was 2.7%.

CONCLUSIONS

This prospective study demonstrates the Endologix Alto is safe and effective in treating AAAs with appropriate anatomy at 1 year. The safety endpoint is met by a 5.3% 30-day major adverse event rate, whereas the effectiveness endpoint is met by a treatment success rate of 96%.

Surgery for late type Ia/IIIb endoleak from a fabric tear and stent fracture of AFX2 stent graft

Technical improvements and labeling updates of the AFX2 stent graft (Endologix Inc, Irvine, CA) seemed to have solved the known issues of its previous generation (AFX Strata). Although most endograft failures after endovascular abdominal aortic aneurysm repair will be managed endovascularly, a small subset of patients will still require secondary open conversion. Partial or complete endograft removal can be required, mainly dependent on the characteristics of the stent graft previously placed. We have report a case of secondary open conversion for late type Ia/IIIb endoleak due to stent fracture and fabric tear of the AFX2 stent graft 3 years after endovascular abdominal aortic aneurysm repair.

Late Type III Endoleaks Are Common in Early Generation Endologix AFX Stent Grafts

INTRODUCTION

Early generation Endologix AFX Endovascular AAA Stent Graft devices are at risk of developing type IIIa (intercomponent/overlap-related) as well as type IIIb (fabric tear) endoleaks over time. Current follow-up studies are limited to short (<24 months) and midterm (24-48 months) reports. The purpose of this study was to identify the incidence of type III endoleaks associated with these endografts over a long-term follow-up (>4 years) period and discuss current management strategies.

METHODS

A retrospective single institution cohort analysis of all Endologix AFX endografts implanted 10/2011-10/2016 was performed. Patient characteristics, imaging and follow-up were obtained via chart review. Type III endoleaks were characterized based on Computed tomography (CT) angiogram/operative findings and confirmed by 2 surgeons. Statistical Analysis was performed with SAS v9.4.

RESULTS

Sixty-three patients underwent AFX stent graft implantation for aneurysmal disease. 47 patients comprised the final cohort for analysis after exclusions were made for primary iliac aneurysms as well as off label use of the device (e.g., hypogastric snorkel) or primary occlusive indications. Average age was 73.3 years with longest follow-up 8.7 years (median 5.2). Most AAA (89.2%) were fusiform with initial median diameter 5.5cm. Initial 30-day mortality was 0%. Of the initial cohort, 10 (21.3%) type III endoleaks were treated, of which 6 (60%) were type IIIa and 4 (40%) were type IIIb. By time to event analysis at latest follow-up freedom from type 3 intervention was 48% at 8 years. Median time to type III endoleak discovery was 4.7 years (range 1.1 -7.2 years) an interval that was similar for type IIIa and type IIIb leak types, p=0.73. Patients with type III endoleaks had average sac growth of 1.3cm over the follow-up interval compared to a net decrease for patients without type III endoleaks, p<.0001. Of the 10 patients treated for type III leaks, 7 (70%) underwent complete endovascular re-lining, one (10%) had partial re-lining while 2 (20.0%) underwent open endograft explant with aortic graft reconstruction. Reintervention 30-day mortality was 0% for all approaches.

CONCLUSION

Early generation Endologix AFX stent grafts have a high rate of type III endoleaks, with freedom from type III leak <50% at 8-year follow-up. Most of these are not detected until several years (>4.5) after initial implantation, beyond the range of the follow-up interval of most published reports. Long-term imaging surveillance is critical and a low threshold for complete relining should be considered with any sign of sac enlargement, even if endoleak is not clearly demonstrated in patients with early generation Endologix AFX grafts.

Midterm outcomes of 455 patients receiving the AFX2 endovascular graft for the treatment of abdominal aortic aneurysm: A retrospective multi-center analysis

Since being introduced into clinical practice the AFX family of endografts has undergone labelling updates, design and manufacturing changes to address a Type III failure mode. The published literature on the performance of the current endograft-AFX2 -is limited to small series with limited follow up. The present study reports the largest series of patients implanted with AFX2 for the treatment of abdominal aortic aneurysms. The study was a retrospective, 5 center study of patients receiving an AFX2 endograft from January 2016 until Dec 2020. Electronic case report forms were provided to four of the centers, with one additional site providing relevant outcomes in an independent dataset. Relevant outcomes were reported via Kaplan-Meier analysis and included all-cause mortality, aneurysm-related mortality, post EVAR aortic rupture, open conversion, device related reinterventions and endoleaks. Among a cohort of 460 patients, 405 underwent elective repair of an AAA, 50 were treated for a ruptured AAA, and 5 were aorto-iliac occlusive disease cases. For the elective cohort (mean age 73.7y, 77% male, mean AAA diameter 5.4cm), the peri-operative mortality was 1.7%. Freedom from aneurysm-related mortality was 98.2% at 1,2,3 and 4 years post-operatively, there were no post-operative aortic ruptures, and 2 patients required open conversion. Freedom from Type Ia endoleaks was 99.4% at 1, 2, 3 and 4 years. Freedom from Type IIIa and Type IIIb endoleaks were 100% and 100% (year 1), 100% and 99.6% (year 2), 99.4% and 99.6% (year 3), 99.4% and 99.6% (year 4) respectively. Freedom from all device-related reintervention (including Type II endoleaks) at 4 y was 86.8%. The AFX2 endograft appears to perform to a satisfactory standard in terms of patient centric outcomes in mid-term follow up. The Type Ia and Type III endoleaks rates at 4y appear to be within acceptable limits. Further follow up studies are warranted.

Predictors of type IIIa endoleak after Endovascular Aortic Repair with anatomic fixation endografts

OBJECTIVE

Concern regarding the use of anatomic fixation endografts was raised as previous data suggested increased risk of late device uncoupling and type IIIa endoleak in this setting. Some risk factors have been identified as predictors of graft failure. We aim to determine if increase in aortic tortuosity index over the time is associated with increased risk of type IIIa endoleak.

METHODS

We conducted a single center retrospective cohort study of patients treated with endovascular repair of infrarenal abdominal aortic aneurysms with the Endologix platform. Patients with at least two postoperative CT scans were included in the analysis. Aortic tortuosity index was determined in the first and last available CT scan to determine any change. Multivariate analysis was performed in order to detect risk predictors of type IIIa endoleak occurrence.

RESULTS

A total of 173 patients were included in the analysis. 21 patients (12.1%) presented type IIIa endoleak. Cumulative freedom from type IIIa endoleak determined by Kaplan-Meier method was 99.4%, 92.5%, 86.1% and 83.3% at 1, 3, 5 and 8 years respectively. Time dependent optimal cutoff values of 0.03 for aortic tortuosity index increase and 15 mm for decrease in modules overlapping over time were obtained with Contal and O'Quigley method to predict type IIIa endoleak. After dichotomizing data around these critical values, a Cox proportional hazards model was obtained to predict type IIIa endoleak occurrence. Maximum preoperative AAA diameter (OR 1.09), smoking (OR 26.67), initial device components overlap (OR 0.91), aortic tortuosity index increase >0.03 (OR 4.56) and decrease in device components overlap > 15 mm (OR 6.13) were associated with type IIIa endoleak occurrence.

CONCLUSIONS

Aortic tortuosity index increase, device components overlap decrease, maximum preoperative aortic diameter, tobacco use and initial device components overlap were predictive of type IIIa endoleak occurrence. Close follow up with CT scan with aortic tortuosity index and device components overlap measure is warranted in these patients and prompt repair seems justified when any of these risk factors is present.

Unibody bifurcated aortic endograft: device description, review of the literature and future perspectives

The unibody (Powerlink/AFX/AFX2) Endovascular AAA device (Endologix Inc., CA, USA) presents a unique design with its long main body and two innate limbs. The device is designed to be deployed and sits on the native aortoiliac bifurcation and represents the only one-piece bifurcated endograft designed to use anatomical fixation for endograft stabilization. According to published literature, the unibody device seems to represent a valid choice in the treatment of abdominal aortic aneurysms. This particular device would seem to satisfactorily perform even in the treatment of more compressed aneurysms (also in off-label association with parallel grafts) and in occlusive pathologies. Ongoing studies will provide new real-life data in a large and unselected patient population to better understand the device’s advantages and limitations.

Two Decades of Abdominal Aortic Endovascular Repair With the Anatomical FiXation at the Aortic Bifurcation in a Large Single-Center Experience

OBJECTIVE

The introduction of new endograft models improved long-term results of abdominal aortic aneurysm (AAA) endovascular repair (EVAR), but most of them maintained an old and unchanged design: a short body and long legs shifting up the flow divider. This study assessed the long-term results of EVAR with unimodular endoprosthesis fixed at the aorto-iliac bifurcation (Anatomical FiXation), in a large, unselected cohort.

MATERIALS AND METHODS

In a single-center, retrospective cohort study, 623 patients selectively treated between 1999 and 2016, were analyzed. Follow-up protocol included at least a computed tomography angiography within 3 months and a duplex ultrasound and clinical exam yearly. All enrolled patients were analyzed by 2020. The primary outcomes were technical success, clinical success, and survival. Secondary outcomes included survival-free from late-open-conversion (LOC), reintervention, and endoleaks.

RESULTS

Median age was 74±11 years and the follow-up 93±54 months. The technical success was achieved in 99.4% and the 30-day clinical success was 98.4%. A 5-year clinical success of 97.7% was registered and at 10 years success was 96.7%. The overall survival at 1, 5, 10, and 15 years was 92.4%, 79.5%, 64.9%, and 45.5%, respectively. Six (0.98%) AAA-related death were registered, 3 caused by infection of the endograft and 3 for secondary rupture. LOCs were 9 (1.47%) and reintervention-free survival at 1, 5, 10, and 15 years were 88.4%, 78.0%, 76.2%, and 74.6%, respectively. Freedom from endoleaks was 88.8% at 1 year and 72.7% at 15 years. A total of 63 high-flow endoleaks were registered (43 type I, 7 type IIIa, 12 type IIIb, and 1 type Ib+IIIb). No migrations were recorded, and the graft limb thrombosis rate was 1.14%. From a multivariate analysis resulted that long-term clinical success appeared to be reduced in patients affected by diabetes [odds ratio (OR) 0.24; p=0.04] and in presence of calcified and thrombotic iliac accesses (OR 0.16; p=0.006).

CONCLUSION

EVAR with the Anatomical FiXation was confirmed to be safe, feasible, and effective to prevent AAA rupture in the long term as well. However, the overall survival remains afflicted by cardiovascular accident. The original concept of unibody bifurcated design allowed a very low rate of graft thrombosis and zeroed the risk of migration and related reintervention.

Modeling and Computational Comparison of the Displacement Forces Exerted between the AFX Unibody Aortic Stent Graft and its Hybrid Combination with a Nitinol-based Proximal Aortic Cuff

BACKGROUND

The bifurcated AFX (Endologix, Inc, Irvine, CA, USA) aortic stent-graft is the sole unibody endograft for the management of Abdominal Aortic Aneurysms (AAA). In order to improve the AFX central sealing and clinical efficacy in challenging cases, a replacement of the central chromium-cobaltium AFX extension with a Nitinol-based proximal aortic cuff has been suggested. Yet, comparative data regarding the hemodynamic performance of this design is missing. Aim of this study was to compare the displacement forces (DF) acting on the hybrid AFX-Endurant design, with the classic AFX and Endurant endografts, in angulated and non-angulated cases based on patient-specific Computational Fluid Dynamics (CFD) simulations.

METHODS

3D endograft models of 11 treated AAA cases were reconstructed from Computed Tomography Angiography (CTA) imaging data: 5 cases of AFX, 3 cases of the combination AFX-Endurant and 3 cases of the classic Endurant design. The DF on the main-body, the iliac limbs, and the entire stent-graft was calculated by processing the velocity and pressure fields generated by pulsatile CFD simulations.

RESULTS

The range of total DF (acting on the whole endograft structure) in the AFX, hybrid AFX-Endurant and Endurant group was 2.5-5.2N, 2.0-5.9N and 1.9-2.9N respectively, with the maximum total DF being lower for Endurant. The DF on the main-body of the classic and hybrid AFX cases were higher than the right and left iliac limbs (2.5-4.9N vs. 0.6-5.3N and 0.7-3.6N respectively). Conversely, the DF on the main-body of the Endurant cases was comparable to the force exerted on the right and left limbs. When separating the cases with respect to their neck angulation, the DF on all endograft parts (main-body, limbs) and on the endograft as a whole were lower for the hybrid AFX-Endurant group compared to the classic AFX and Endurant groups, for cases with almost straight neck.

CONCLUSION

The off-label use of the hybrid AFX-Endurant stent-graft does not seem superior to the conventional AFX or Endurant endografts in angulated cases but was associated with lower DF than AFX or Endurant in non-angulated cases. The clinical value and utility of these findings remain to be elucidated.

Early and midterm outcomes of endovascular aneurysm repair with an ultra-low-profile endograft from the Triveneto Incraft Registry

OBJECTIVE

We evaluated the early and midterm outcomes of the Incraft (Cordis Corp, Bridgewater, NJ) ultra-low-profile endograft by analyzing data from the Triveneto Incraft Registry (TIR).

METHODS

TIR is an independent multicenter cohort registry of 10 vascular surgery units in the Triveneto area (Northeast Italy). A prospective analysis of patients electively treated with Incraft from September 2014 to June 2019 was performed. The main outcomes were technical success, major 30-day complications, 30-day aneurysm-related death, freedom from reintervention, and mortality rate during follow-up and were analyzed using Kaplan-Meier curves. Univariable Cox regression was used to evaluate the associations between anatomic complexity factors and reintervention.

RESULTS

During the study period, 209 patients were included in the registry. Their mean age was 76.9 ± 7.7 years and the Society for Vascular Surgery comorbidity score was 0.97 ± 0.52. Most patients (n = 181; 86.6%) had presented with at least one complex anatomic factor: aortic neck angle α <135° in 31 patients (14.8%), conic neck in 17 patients (8.2%), iliac tortuosity index τ >1.5 in 102 (48.8%), iliac artery calcification >50% in 106 (50.7%), and external iliac artery <6 mm in 45 (21.5%). The concurrent presence of two or more complex iliac anatomic factors was present in 67 patients (32.1%). The technical success rate was 99.5%, and the early major complication rate was 1.5% (one limb occlusion, one iliac branch stenosis, one type III endoleak [EL]). No 30-day mortality was recorded. The mean follow-up period was 18.5 ± 13.2 months. The overall mortality was 9.5% (n = 18), none related to the aneurysm. The freedom from reintervention rate was 92.1%. Of these patients, six (3.2%) had been treated for type II EL embolization, one (0.5%) for type IA EL, four (2.1%) for iliac branch occlusion, and one (0.5%) for flow-limiting external iliac artery dissection. None of the single anatomic factors analyzed were predictive of reintervention. However, the association of two or more complex iliac anatomic factors was predictive of related reintervention (hazard ratio, 7.25; P = .014). The crude reintervention rate in this complex subgroup of patients was low (4 of 67; 6%).

CONCLUSIONS

Data from the TIR have demonstrated excellent early and midterm outcomes of endovascular aneurysm repair using the Incraft stent graft in patients with complex anatomy. The concurrent presence of two or more complex iliac anatomic factors still represent an issue for endovascular aneurysm repair success. However, the technical characteristics of this device resulted in low intervention rates, even for patients with these challenging issues.

Occurrence and outcomes of type 3 endoleaks in endovascular aortic repair within the Vascular Quality Initiative database

Objectives

Type 3 endoleaks (T3ELs) represent a lack of aneurysm protection from systemic pressure. Previous studies have found a ~2% incidence of T3EL after standard infrarenal endovascular aneurysm repair (EVAR); however, no prior studies with new-generation devices have been able to determine an association between T3EL and clinical outcomes. Here we examine T3EL within the Society for Vascular Surgery Vascular Quality Initiative (VQI) to define rates of occurrence, rates and modes of reintervention, and clinical consequences of these endoleaks.

Design and setting

Participants receiving infrarenal EVAR in the VQI from January 2003 to September 2018 were analyzed in a retrospective cohort study.

Participants

Of 42 246 entries in the EVAR procedural registry, 41 604 had complete procedural information and were included in analysis. Of these, 36 082 had long-term follow-up, and 26 422 had follow-up (9-21 months per VQI reporting standards) with complete endoleak data recorded.

Interventions

All patients included in this study underwent an infrarenal EVAR.

Results

Within the VQI database, the rate of T3EL in infrarenal EVAR during index hospitalization was 0.37% (n=157/41 604), of which 85% were due to midgraft separation and 15% were due to fabric disruptions. Out of the 157 index hospitalization T3ELs, 4.5% (n=7) received procedural reintervention during that hospitalization, which accounted for 1% of all index hospitalization reinterventions. During the 21-month follow-up, the rate of incident T3EL was 0.7% (n=205/26 422), which accounted for 5% of all endoleaks seen during follow-up. Reinterventions for incident T3EL at follow-up were done in 30 patients (rate 0.1%), which accounted for 9% of endoleak reinterventions and 3.3% of all reinterventions. The presence of incident T3EL found during follow-up was associated with a significant decrease in 5-year survival (74% vs 80%, respectively; p=0.041) in Kaplan-Meier analysis.

Conclusion

T3ELs rates at placement and follow-up remain low; however, the majority reported in long-term follow-up are incident and these incident endoleaks are associated with decreased survival in EVAR.

Midterm outcomes for 605 patients receiving Endologix AFX or AFX2 Endovascular AAA Systems in an integrated healthcare system

BACKGROUND

Endologix issued important safety updates for the AFX Endovascular AAA System in 2016 and 2018 owing to the risk of type III endoleaks. Outcomes with these devices are limited to small case series with short-term follow-up. We describe the midterm outcomes for a large cohort of patients who received an Endologix AFX or AFX2 device.

STUDY DESIGN

Data from an integrated healthcare system's implant registry, which prospectively monitors all patients after endovascular aortic repair, was used for this descriptive study. Patients undergoing endovascular aortic repair with three AFX System variations (Strata [AFX-S], Duraply [AFX-D], and AFX2 with Duraply [AFX2]) were identified (2011-2017). Crude cumulative event probabilities for endoleak (types I and III), major reintervention, conversion to open, rupture, and mortality (aneurysm related and all cause) were estimated.

RESULTS

Among 605 patients, 375 received AFX-S, 197 received AFX-D, and 33 received AFX2. Median follow-up for the cohort was 3.9 (interquartile range, 2.5-5.1) years. The crude 2-year incidence of overall endoleak, any subsequent reintervention or conversion, and mortality was 8.8% (95% confidence interval [CI], 6.3-12.3), 12.0% (95% CI, 9.1-15.9), and 8.8% (95% CI, 6.3-12.2) for AFX-S. Respective estimates for AFX-D were 7.9% (95% CI, 4.8-13.0), 10.6% (95% CI, 6.9-16.1), and 9.7% (95% CI, 6.3-14.7); for AFX2, they were 14.1% (95% CI, 4.7-38.2), 16.2% (95% CI, 6.4-37.7), and 21.2% (95% CI, 10.7-39.4).

CONCLUSIONS

The midterm outcomes of a large U.S. patient cohort with an Endologix AFX or AFX2 System demonstrate a concerning rate of adverse postoperative events. Patients with these devices should receive close clinical surveillance to prevent device-related adverse events.

Diagnosis and relining techniques for delayed type IIIB endoleaks with the second-generation AFX endograft

Type IIIB endoleaks resulting from endograft fabric tear are an uncommon but serious late complication of endovascular aortic aneurysm repair. The Strata fabric used in the earlier generation AFX endograft (updated to Duraply in October 2014) has been associated with an increased frequency of these events. Herein we report on two patients exhibiting delayed type IIIB endoleaks after AFX device insertion to treat an abdominal aortic aneurysm and discuss optimal relining techniques.

Aggressive Surveillance Is Needed to Detect Endoleaks and Junctional Separation between Device Components after Zenith Fenestrated Aortic Reconstruction

BACKGROUND

Junctional separation and resulting type IIIa endoleak is a well-known problem after EVAR (endovascular aneurysm repair). This complication results in sac pressurization, enlargement, and eventual rupture. In this manuscript, we review the incidence of this late finding in our experience with the Cook Zenith fenestrated endoprosthesis (ZFEN, Bloomington, IN).

METHODS

A retrospective review was performed of a prospectively maintained institutional ZFEN fenestrated EVAR database capturing all ZFENs implanted at a large-volume, academic hospital system. Patients who experienced junctional separation between the fenestrated main body and distal bifurcated graft (with or without type IIIa endoleak) at any time after initial endoprosthesis implantation were subject to further evaluation of imaging and medical records to abstract clinical courses.

RESULTS

In 110 ZFENs implanted from October 2012 to December 2017 followed for a mean of 1.5 years, we observed a 4.5% and 2.7% incidence of clinically significant junctional separation and type IIIa endoleak, respectively. Junctional separation was directly related to concurrent type Ib endoleak in all 5 patients. Three patients presented with sac enlargement. One patient did not demonstrate any evidence of clinically significant endoleak and had a decreasing sac size during follow-up imaging. The mean time to diagnosis of modular separation in these patients was 40 months. Junctional separation was captured in surveillance in 2 patients and reintervened upon before manifestation of endoleak. However, the remaining 3 patients completed modular separation resulting in rupture and emergent intervention in 2 and an aortic-related mortality in the other.

CONCLUSIONS

Junctional separation between the fenestrated main and distal bifurcated body with the potential for type IIIa endoleak is an established complication associated with the ZFEN platform. Therefore, we advocate for maximizing aortic overlap during the index procedure followed by aggressive surveillance and treatment of stent overlap loss captured on imaging.