A systematic review on anatomical predictors of abdominal aortic aneurysm remodeling after endovascular repair

Single Centre Evaluation of the Proposal of the European Society for Vascular Surgery Abdominal Aortic Aneurysm Guidelines to Stratify Surveillance after Endovascular Aortic Aneurysm Repair

OBJECTIVE

The aim of this study was to evaluate and compare methods that identify patients at low risk of developing complications after endovascular aortic aneurysm repair (EVAR) and who would thus not require surveillance in the first post-operative years.

METHODS

This was a retrospective, single centre, cohort study including all patients after elective infrarenal EVAR with both immediate post-operative and one year computed tomography angiography (CTA) imaging. Patients were categorised by adherence to instructions for use (IFU), adequate seal, and absence of endoleak (method A1), and without high risk features (method A2) on the first post-operative CTA. Additionally, these patients were dichotomised based on aneurysm sac shrinkage at one year (> 5 mm maximum diameter reduction, method B). Outcomes were graft related adverse events and all cause death. Negative predictive value (NPV) was used to compare risk classifications.

RESULTS

Of 422 eligible patients, 297 underwent the required imaging for classification: 140 (47.1%) and 109 (36.7%) patients were classified as low risk based on methods A1 and A2, respectively, while 147 (49.5%) were assumed low risk based on method B. The five year cumulative incidence of adverse events in low risk patients according to method A1 was 14.7% (95% confidence interval [CI] 8.5 - 20.9%), similar to method A2 (16.1%, 95% CI 8.8 - 23.4%) and method B (15.4%, 95% CI 9.3 - 21.5%). The five year median NPV for adverse events for method A1 was 85.2% (95% CI 79.7 - 90.8%), comparable with method A2 (83.8%, 95% CI 76.9 - 90.3%; p = .37) and method B (84.7%, 95% CI 79.4 - 89.5%; p = .87). Significantly higher NPVs were found by combining method A1 or A2 with method B, with median values ≥ 95% up to four years after EVAR. The five year NPV for death did not differ between methods (five year NPVmethod A1, 81.7%, 95% CI 76.6 - 86.5%).

CONCLUSION

Refraining from imaging in the first five years after EVAR in patients treated within IFU and with a favourable post-operative CTA would have failed to detect important complications at an early stage. It is proposed to combine the post-operative CTA with sac shrinkage at one year in order to stratify post-EVAR surveillance. No benefit was found in considering the high risk features suggested in the European Society for Vascular Surgery (ESVS) guidelines.

Multimodal Artificial Intelligence Model for Prediction of Abdominal Aortic Aneurysm Shrinkage After Endovascular Repair ( the ART in EVAR study)

PURPOSE

The goal of the study described in this protocol is to build a multimodal artificial intelligence (AI) model to predict abdominal aortic aneurysm (AAA) shrinkage 1 year after endovascular aneurysm repair (EVAR).

METHODS

In this retrospective observational multicenter study, approximately 1000 patients will be enrolled from hospital records of 5 experienced vascular centers. Patients will be included if they underwent elective EVAR for infrarenal AAA with initial assisted technical success and had imaging available of the same modality preoperatively and at 1-year follow-up (CTA-CTA or US-US). Data collection will include baseline and vascular characteristics, medication use, procedural data, preoperative and postoperative imaging data, follow-up data, and complications.

PROPOSED ANALYSES

The cohort will be stratified into 3 groups of AAA remodeling based on the maximum AAA diameter difference between the preoperative and 1-year postoperative moment. Patients with a diameter reduction of ≥5 mm will be assigned to the AAA shrinkage group, cases with an increase of ≥5 mm will be assigned to the AAA growth group, and patients with a diameter increase or reduction of <5 mm will be assigned to the stable AAA group. Furthermore, an additional fourth group will include all patients who underwent an AAA-related reintervention within the first year after EVAR, because both the complication and the reintervention might have influenced the state of AAA remodeling at 1 year. The preoperative and postoperative CTA scans will be used for anatomical AAA analysis and biomechanical assessment through semi-automatic segmentation and finite element analysis. All collected clinical, biomechanical, and imaging data will be used to create an AI prediction model for AAA shrinkage. Explainable AI techniques will be used to identify the most descriptive input features in the model. Predicting factors resulting from the AI model will be compared with conventional univariate and multivariate logistic regression analyses to find the best model for the prediction of AAA shrinkage. The study is registered at www.clinicaltrials.gov under the registration number NCT06250998.

CLINICAL IMPACT

This study aims to develop a robust and high-performance AI model for predicting AAA shrinkage one-year after EVAR, with great potential for optimizing both EVAR treatment and follow-up. The model can identify cases with an initially lower chance of early AAA shrinkage, in whom EVAR-treatment could be tailored by including additional preoperative coil embolization, active sac management and/or postoperative tranexamic acid therapy, which have shown to promote AAA shrinkage rate but are too complex and costly to perform in all patients. The model could aid in stratification of post-EVAR surveillance based on the patient's individual risk and possibly decrease follow-up for the 40-50% of patients who will experience AAA sac shrinkage. Overall, the AI prediction model is expected to improve patient survival and decrease the number of reinterventions after EVAR and associated healthcare costs.

Impact of Sex-Related Differences in Infrarenal Aortic Neck Morphology on Outcomes of Endovascular Aneurysm Repair for Similar-Sized Aortic Aneurysm

Objectives: This study aimed to evaluate whether gender-related anatomical differences in proximal aortic neck morphology affect the feasibility and outcomes of endovascular aortic aneurysm repair (EVAR) in women with abdominal aortic aneurysms (AAA). Methods: This study performed a retrospective analysis of patients electively treated by EVAR for infrarenal AAA between January 2019 and December 2023. Demographics, anatomical characteristics, and stent graft details were analyzed. The primary endpoint was technical success. Secondary endpoints included freedom from aortic and neck-related reinterventions, endoleak rate, and freedom from aneurysm-related mortality during follow-up. Technical aspects, including adherence to the instructions for use (IFUs), were retrospectively analyzed. Results: One-hundred-seventeen patients (fifty-six females; mean age 76.2 ± 5.3 years) underwent elective EVAR for AAA. Demographics and comorbidities were homogeneous across genders. Female patients (Group A) demonstrated a higher prevalence of hostile proximal aortic neck features, including neck length < 10 mm and angulation > 60° (p = 0.009, p = 0.029, respectively) and a higher frequency of off-label EVAR procedures (28.6% vs. 11.5%; p = 0.034). The overall technical success rate was 98.3%, with no significant differences between genders in terms of stent graft selection, use of suprarenal fixation, or incidence of type 1-3 endoleaks. The median follow-up period was 35.2 ± 12.7 months, showing comparable rates of neck-related reinterventions, open conversions, and aneurysm-related mortality between genders. Notably, off-label EVAR was identified as an independent risk factor for type 1A endoleaks, reinterventions, and aneurysm-related mortality (p < 0.00001, p < 0.0001, and p = 0.001, respectively). Conclusions: Female patients undergoing EVAR often present with hostile proximal aortic neck features and are treated at an older age than males. Despite these differences, technical success rates and mid- to long-term outcomes were comparable between genders, with no variation in stent graft selection or suprarenal fixation use. Effective procedural planning, device selection, and surgical expertise appear to mitigate historical gender-related anatomical challenges. Further large-scale studies are needed to confirm whether anatomical factors alone drive outcomes, irrespective of gender.

The Impact of Diabetes Mellitus and Metformin Use on Outcomes After Endovascular Aneurysm Repair

Objective: To study the influence of diabetes mellitus (DM) and metformin treatment on aneurysm sac remodeling after endovascular aneurysm repair (EVAR). Methods: A retrospective single-center cohort analysis was conducted on consecutive patients who underwent elective EVAR for an infrarenal abdominal aortic aneurysm (AAA) between January 2011 and December 2021. Differences between study groups were analyzed and Kaplan-Meier analysis were employed to describe overall and reintervention-free survival. Cox regression analysis was performed to identify predictors of sac shrinkage. Results: A total of 529 patients were included: 74 (14.0%) had DM and metformin treatment, 26 (4.9%) had DM without metformin treatment, and 429 (81.1%) did not have DM. At one-year follow-up, diabetic patients showed significantly less sac shrinkage compared to non-diabetic patients (40.0% vs. 52.0%; p = 0.038), with a trend toward more stable sac behavior in diabetic patients (52% vs. 42%; p = 0.055). At last follow-up, sac shrinkage was significantly less in diabetic patients on metformin treatment compared to non-diabetics (48.6% vs. 59.9%; p = 0.047). No differences in sac shrinkage were observed between diabetics with and without metformin treatment. The presence of endoleak was significantly higher in groups showing stable sac behavior and growth. Through nine-year follow-up, overall survival was significantly less in diabetic patients compared to non-diabetic ones (23.5% vs. 37.5%; p < 0.001). Conclusions: This study showed a negative impact of diabetes mellitus and metformin treatment on sac shrinkage following EVAR. The presence of any type of endoleak was associated with reduced sac shrinkage at both time points. Overall survival was significantly lower in diabetic patients compared to non-diabetic patients.

The Long-Term Progression of Aneurysmal Disease in Common Iliac Arteries After Standard EVAR and Its Clinical Implications

Introduction: The progression of aneurysmal disease in the common iliac arteries (CIAs) after EVAR remains an insufficiently investigated field. The purpose of this study is to investigate the long-term outcomes of standard elective EVAR with a variety of last-generation bifurcated aortic endografts in relation with the progression of aneurysmal disease in the CIAs. Methods: This is a prospective cohort study of 168 patients, who were treated with six different endografts between 2013 and 2018 and completed the 5-year computed tomography aortoangiography (CTA) follow-up. Postoperative CTA analysis included CIA measurements at four diameters' points and two length levels in three postoperative time spots: first, 24th, and 60th months. All EVAR-related adverse events were recorded, including migrations, endoleaks, limb occlusions, reinterventions, ruptures, and mortality. Results: At both time intervals, a significant and nearly linear dilatation and elongation of CIAs was evident. The mean percent increase, among all diameter points measured, was 11.7% at 24 months and 22.8% at 60 months (p < 0.001) with a nearly constant mean increase rate by 0.07 mm per month. The corresponding monthly elongation rate of total CIA length was 0.26 mm at 24 months and 0.34 mm at 5 years (p < 0.001). The respective monthly lengthening of CIAs' uncovered (from stent graft) segment was 0.10 and 0.15 mm, and the overall increase rate at 60 months was up to 53.9% (p < 0.001). A total of 20 EVAR-related events were recorded, and multivariate analysis revealed that CIA dilatation served as a significant and independent predictor of long-term EVAR failures, increasing the likelihood of adverse events by 2.8-fold. Conclusions: Analysis of long-term geometric CIA remodeling after a standard EVAR revealed a significant progression of aneurysmal disease in CIAs, which was associated with worsening EVAR outcomes and emphasizes the importance of a rigorous and extensive follow-up protocol to maintain the long-term EVAR effectiveness.

Different Proteins as Biomarkers for Sac Shrinkage After Endovascular Aortic Repair of Abdominal Aortic Aneurysms

BACKGROUND

This study aims to identify circulating biomarkers by using proteomic analysis associated with sac shrinkage or expansion in patients undergoing endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs).

METHODS

Plasma samples were analysed from 32 patients treated with EVAR between 10/2009 and 10/2020. Patients were divided into two groups based on postoperative sac behaviour: sac shrinkage (≥5 mm reduction) and no shrinkage (stabilisation or expansion). Proteomic analysis was performed using high-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS), with abundant protein depletion to enhance the detection of low-abundant proteins.

RESULTS

Of the 32 patients, 20 exhibited sac shrinkage, and 12 showed no shrinkage. Proteomic analysis identified 632 proteins, with significant differential abundance observed after adjusting for relevant clinical parameters. Notably, neurogranin (NRGN) levels were significantly associated with hypertension and smoking, while casein alpha S1 (CSN1S1) levels varied with statin use. Differentially abundant proteins related to aortic diameter included calpastatin, SCUBE3, and ubiquitin-conjugating enzyme E2, among others.

CONCLUSIONS

Proteomic profiling revealed distinct biomarker patterns associated with sac behaviour in EVAR-treated AAA patients. These findings suggest potential therapeutic targets for enhancing EVAR outcomes and underscore the need for further investigation into the biological mechanisms underlying aneurysm sac shrinkage and stability.

Endosutured Aneurysm Repair of Abdominal Aortic Aneurysms with Short Necks Achieves Acceptable Midterm Outcomes-Results from the Peru Registry

BACKGROUND

The study aims to describe midterm outcomes following treatment of infrarenal abdominal aortic aneurysms (AAAs) with short necks by endosutured aneurysm repair using the Heli-FX EndoAnchor system.

METHODS

This is a retrospective study of prospectively collected data from 9 vascular surgery departments between June 2010 and December 2019, including treated AAAs with neck lengths ≤10 mm. The decision for the use of EndoAnchors was made by the treating surgeon or multidisciplinary aortic committee according to each center's practice. There were 2 Groups further assessed according to neck length, A (≥4 and <7 mm) and B (≥7 and ≤10 mm). The main outcomes analyzed were technical success, freedom from type Ia endoleaks (TIaELs), sac size increase, all-cause and aneurysm-related mortality.

RESULTS

Seventy-six patients were included in the study, 17 fell into Group A and 59 into Group B. Median follow-up for the cohort was 40.5 (interquartile range 12-61) months. A median of 6 (interquartile range 3) EndoAnchors were deployed in each subject. Technical success was 86.8% for the total group, 82.4% and 88.1% (P = 0.534) for Groups A and B respectively. Six out of 10 (60%) of TIaELs at the completion angiographies showed spontaneous resolution. Cumulative freedom from TIaEL at 3 and 5 years for the total group was 89% and 84% respectively; this was 93% and 74% for Group A and 88% at both intervals in Group B (P = 0.545). In total, there were 7 (9.2%) patients presenting with TIaELs over the entire study period. Two (11.8%) in Group A and 5 (8.5%) in Group B (P = 0.679). There were more patients with sac regression in Group B (Group A = 6-35.3% vs. Group B = 34-57.6%, P = 0.230) with no statistical significance. All-cause mortality was 19 (25%) patients, with no difference (4-23.5% vs. 15-25.4%, P = 0.874) between groups; whereas aneurysm-related mortality occurred in 1 patient from Group A and 3 from Group B.

CONCLUSIONS

This study demonstrates reasonable outcomes for patients with short-necked AAAs treated by endosutured aneurysm repair in terms of TIaELs up to 5-year follow-up. EndoAnchor use should be judiciously evaluated in short necks and may be a reasonable option when anatomical constraints are encountered, mainly for those with 7-10 mm neck lengths. Shorter neck length aspects, as indicated by the results from Group A, may be an alternative when no other options are available or feasible.

Late post-EVAR abdominal aortic aneurysm rupture: a meta-analysis study

This study presents updated information on post-endovascular aneurysm repair (EVAR) late aortic rupture (LAR) as the data in the literature are limited. It comprises a meta-analysis based on the recent evidence regarding the incidence, causes, treatment outcomes, and prognosis of post-EVAR. A meta-analysis was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies were identified by searching electronic databases and scanning bibliographic references from 1991 to April 1, 2023. Our analysis provided evidence that the most common causes of rupture after EVAR were type Ia and Ib Endoleaks (Els). Post-rupture mortality after EVAR was high (35.6%) and comparable to the morbidity of de novo ruptures. Endovascular repair appears to have better results compared to conversion to open repair. A significant number of patients had prior endovascular reoperations and inadequate follow-up. Patient compliance with the surveillance protocol is mandatory.

Early and Mid-Term Outcomes of Transcaval Embolization for Type 2 Endoleak after Endovascular Aortic Repair

Background: Among the endovascular approaches for the management of endoleak type 2 (EL 2), transcaval embolization (TCE) has shown encouraging outcomes. However, the literature is still limited. This study aimed to present the early and mid-term outcomes of TCE for EL 2 after endovascular aortic repair. Methods: A retrospective, single-center analysis of consecutive patients managed with TCE for EL 2 after standard or complex endovascular aortic repair, from August 2015 to March 2024, was conducted. The indication for TCE was the presence of an EL 2 related to ≥5 mm sac increase, compared to the first imaging after aneurysm exclusion or the smallest diameter during follow-up. Patients managed with TCE for other types of endoleaks were excluded. The primary outcomes were technical and clinical successes during follow-up. Results: Forty-three patients were included (mean age: 75.1 ± 6.0 years, 90.7% males). Technical success was 97.7%. Selective embolization was performed in 48.8% and non-selective in 51.2%. No death was recorded at 30 days. The estimated clinical success was 90.0% (standard error; SE: 6.7%) and the freedom from EL 2 was 89.0% (SE 6.4%) at 36 months. Cox regression analysis showed that the type of embolization (selective vs. non-selective), type of previous repair (f/bEVAR vs. EVAR), and use of anticoagulants did not affect follow-up outcomes. Reinterventions related to EL 2 were performed in 12.5%; three underwent an open conversion. Conclusions: TCE was related to high technical success and limited peri-operative morbidity, regardless of the type of initial endovascular aortic repair. Clinical success was encouraging with reinterventions for EL 2 affecting 12.5% of patients.

The Effect of EndoAnchors on Aneurysm Sac Regression for Patients Treated With Infrarenal Endovascular Repair With Hostile Neck Anatomies: A Propensity Scored Analysis

PURPOSE

To analyze sac evolution patterns in matched patients with hostile neck anatomy (HNA) treated with standard endovascular aneurysm repair (sEVAR) and endosutured aneurysm repair (ESAR).

METHODS

Observational retrospective study using prospectively collected data between June 2010 and December 2019. ESAR group data were extracted from the primary arm of the PERU registry with an assigned identifier (NCT04100499) at 8 centers and those from the sEVAR came from 4 centers. Suitability for inclusion required: no proximal endograft adjuncts (besides EndoAnchor use), ≤15 mm neck length and minimum of 12-months follow-up imaging. Bubble-shaped neck (noncylindrical short neck with discontinuous seal) aspect was analyzed. Both groups were analyzed using propensity score matching (PSM) for aortic neck length, width, angulation, and device fixation type. Main outcome assessed was sac evolution patterns (sac expansion and regression were defined as >5mm increase or decrease, of the maximum sac diameter respectively; all AAAs within this ±5 mm range in diameter change were considered stable) and secondary outcomes were type-Ia endoleaks; other endoleaks and mortality. A power analysis calculation >80% was confirmed for sac regression evaluation.

RESULTS

After exclusions, PSM resulted in 96 ESAR and 96 sEVAR patients. Mean imaging follow-up (months) was 44.4±21.3 versus 43.0±19.6 (p=0.643), respectively. The overall number of patients achieving sac regression was higher in the ESAR group (n=57, 59.4% vs n=31, 32.3%; p<0.001) and the cumulative sac regression achieved at 5 years was 65% versus 38% (p=0.003) in favor of the ESAR group. There were no statistically significant differences in type-Ia endoleak and/or other endoleaks. Univariate analysis for sac regression patients in the sEVAR and ESAR group individually showed the bubble-shape neck as a predictor of sac regression failure. There were no statistical differences in overall and aneurysm-related mortality.

CONCLUSION

Endosutured aneurysm repair provided improved rates of sac regression for patients with AAA and HNA when compared with sEVAR at midterm and up to 5 years, despite similar rates of type-Ia endoleaks, and the need to consider some important limitations. The presence of bubble-shaped neck was a predictor of sac regression failure for both groups equally.

CLINICAL IMPACT

The use of EndoAnchors aids and improves EVAR treatment in hostile neck anatomies by an increased rate of sac regression when compared to EVAR treatment alone in up to 5 year analysis. Moreover, a trend to reduced number of type Ia endoleaks is also achieved, although not significant in the present study. This data, adds to current and growing evidence on the usefulness of EndoAnchors for AAA endovascular treatment.

Importance of sac regression after EVAR and the role of EndoAnchors

The initial success and widespread adoption of endovascular aneurysm repair (EVAR) for the treatment of abdominal aortic aneurysms have been tempered by numerous reports of secondary interventions and increased long-term mortality compared with open repair. Over the past decade, several studies on postoperative sac dynamics after EVAR have suggested that the presence of sac regression is a benign feature with a favorable prognosis. Conversely, increasing sacs and even stable sacs can be indicators of more unstable sac behavior with worse outcomes in the long-term. Endoleaks were initially perceived as the main drivers of sac behavior. However, the observation that sac regression can occur in the presence of endoleaks, and vice versa - increasing sacs without evidence of endoleak - on imaging studies, suggests the involvement of other contributing factors. These factors can be divided into anatomical factors, patient characteristics, sac thrombus composition, and device-related factors. The shift of interest away from especially type 2 endoleaks is further supported by promising results with the use of EndoAnchors regarding postoperative sac behavior. This review provides an overview of the existing literature on the implications and known risk factors of post-EVAR sac behavior, describes the accurate measurement of sac behavior, and discusses the use of EndoAnchors to promote sac regression.

Long-Term Outcomes of Simple Endovascular Aneurysm Repair Based on the Initial Aortic Diameter

PURPOSE

We aimed to investigate the effects of initial abdominal aortic aneurysm (AAA) diameter on aneurysmal sac expansion/shrinkage, endoleaks, and reintervention postelective simple endovascular aneurysm repair (EVAR).

METHODS

Overall, 228 patients monitored for >1 year after EVAR were analyzed. Male and female participants with initial AAA diameters <55 mm and <50 mm, respectively, composed the small group (group S), while those with initial AAA diameters ≥55 mm (men) and ≥50 mm (women) composed the large group (group L). Aneurysmal sac expansion of 10 mm and/or reintervention during follow-up (composite event) and its related factors were evaluated.

RESULTS

The 5-year freedom from composite event rate was significantly higher in group S (92.4 ± 2.8%) than that in group L (79.1 ± 4.9%; P <0.01). Multivariate analysis revealed AAA diameters before EVAR in group S (hazard ratio, 0.38; 95% confidence interval, 0.18-0.81; P = 0.01) and type II endoleak (T2EL) at discharge (hazard ratio, 2.83; 95% confidence interval, 1.29-6.20; P <0.01) as factors associated with the composite event. The freedom from composite event rate decreased to 51 ± 13% at 5 years in group L with T2EL.

CONCLUSIONS

Group S had high freedom from composite event rate; in group L, the rate decreased to 51% at 5 years with T2EL at discharge.

Artificial Intelligence-Assisted Sac Diameter Assessment for Complex Endovascular Aortic Repair

PURPOSE

Artificial intelligence (AI) using an automated, deep learning-based method, Augmented Radiology for Vascular Aneurysm (ARVA), has been verified as a viable aide in aneurysm morphology assessment. The aim of this study was to evaluate the accuracy of ARVA when analyzing preoperative and postoperative computed tomography angiography (CTA) in patients managed with fenestrated endovascular repair (FEVAR) for complex aortic aneurysms (cAAs).

MATERIALS AND METHODS

Preoperative and postoperative CTAs from 50 patients (n=100 CTAs) who underwent FEVAR for cAAs were extracted from the picture archiving and communication system (PACS) of a single aortic center equipped with ARVA. All studies underwent automated AI aneurysm morphology assessment by ARVA. Appropriate identification of the outer wall of the aorta was verified by manual review of the AI-generated overlays for each patient. Maximum outer-wall aortic diameters were measured by 2 clinicians using multiplanar reconstruction (MPR) and curved planar reformatting (CPR), and among studies where the aortic wall was appropriately identified by ARVA, they were compared with ARVA automated measurements.

RESULTS

Identification of the outer wall of the aorta was accurate in 89% of CTA studies. Among these, diameter measurements by ARVA were comparable to clinician measurements by MPR or CPR, with a median absolute difference of 2.4 mm on the preoperative CTAs and 1.6 mm on the postoperative CTAs. Of note, no significant difference was detected between clinician measurements using MPR or CPR on preoperative and postoperative scans (range 0.5-0.9 mm).

CONCLUSION

For patients with cAAs managed with FEVAR, ARVA provides accurate preoperative and postoperative assessment of aortic diameter in 89% of studies. This technology may provide an opportunity to automate cAA morphology assessment in most cases where time-intensive, manual clinician measurements are currently required.

CLINICAL IMPACT

In this retrospective analysis of preoperative and postoperative imaging from 50 patients managed with FEVAR, AI provided accurate aortic diameter measurements in 89% of the CTAs reviewed, despite the complexity of the aortic anatomies, and in post-operative CTAs despite metal artifact from stent grafts, markers and embolization materials. Outliers with imprecise automated aortic overlays were easily identified by scrolling through the axial AI-generated segmentation MPR cuts of the entire aorta.This study supports the notion that such emerging AI technologies can improve efficiency of routine clinician workflows while maintaining excellent measurement accuracy when analyzing complex aortic anatomies by CTA.

Artificial Intelligence Application to Screen Abdominal Aortic Aneurysm Using Computed tomography Angiography

The aim of our study is to validate a totally automated deep learning (DL)-based segmentation pipeline to screen abdominal aortic aneurysms (AAA) in computed tomography angiography (CTA) scans. We retrospectively evaluated 73 thoraco-abdominal CTAs (48 AAA and 25 control CTA) by means of a DL-based segmentation pipeline built on a 2.5D convolutional neural network (CNN) architecture to segment lumen and thrombus of the aorta. The maximum aortic diameter of the abdominal tract was compared using a threshold value (30 mm). Blinded manual measurements from a radiologist were done in order to create a true comparison. The screening pipeline was tested on 48 patients with aneurysm and 25 without aneurysm. The average diameter manually measured was 51.1 ± 14.4 mm for patients with aneurysms and 21.7 ± 3.6 mm for patients without aneurysms. The pipeline correctly classified 47 AAA out of 48 and 24 control patients out of 25 with 97% accuracy, 98% sensitivity, and 96% specificity. The automated pipeline of aneurysm measurements in the abdominal tract reported a median error with regard to the maximum abdominal diameter measurement of 1.3 mm. Our approach allowed for the maximum diameter of 51.2 ± 14.3 mm in patients with aneurysm and 22.0 ± 4.0 mm in patients without an aneurysm. The DL-based screening for AAA is a feasible and accurate method, calling for further validation using a larger pool of diagnostic images towards its clinical use.

Mechanism of sac expansion without evident endoleak analyzed with X ray phase-contrast tomography

Objective

Synchrotron radiation-based X ray phase-contrast tomography (XPCT) was used in this study to evaluate abdominal aorta specimens from patients with sac expansion without evidence of an endoleak (endotension) following endovascular aortic repair (EVAR) for an abdominal aortic aneurysm (AAA). The aim of this study was to analyze the morphologic structure of the aortic wall in patients with this condition and to establish the cause of the endotension.

Methods

Human aortic specimens of the abdominal aorta were obtained during open repair, fixed with formalin, and analyzed among three groups. Group A was specimens from open abdominal aortic aneurysm repairs (n = 7). Group E was specimens from sac expansion without an evident endoleak after EVAR (n = 7). Group N was specimens from non-aneurysmal "normal" cadaveric abdominal aortas (n = 5). Using XPCT (effective voxel size, 12.5 μm; density resolution, 1 mg/cm3), we measured the density of the tunica media (TM) in six regions of each sample. Then, any changes to the elastic lamina and the vasa vasorum were analyzed pathologically. The specimens were immunohistochemically examined with anti-CD31 and vascular endothelial growth factor antibodies.

Results

The time from EVAR to open aortic repair was 64.2 ± 7.2 months. There were significant differences in the thickness of the TM among three groups: 0.98 ± 0.03 mm in Group N; 0.31 ± 0.01 mm in Group A; and 0.15 ± 0.03 mm in Group E (P < .005). There were significant differences in the TM density among the groups: 1.087 ± 0.004 g/cm3 in Group N; 1.070 ± 0.001 g/cm3 in Group A; and 1.062 ± 0.007 g/cm3 in Group E (P < .005). Differences in the thickness and density of the TM correlated with the thickness of the elastic lamina; in Group N, uniform high-density elastic fibers were observed in the TM. By contrast, a thinning of the elastic lamina in the TM was observed in Group A. A marked thinness and loss of elastic fibers was observed in Group E. CD31 immunostaining revealed that the vasa vasorum was localized in the adventitia and inside the outer third of the TM in Group N, and in the middle of the TM in Group A. In Group E, the vasa vasorum advanced up to the intima with vascular endothelial growth factor-positive cells in the intimal section.

Conclusions

XPCT could be used to demonstrate the densitometric property of the aortic aneurysmal wall after EVAR. We confirmed that the deformation process that occurs in the sac expansion after EVAR without evidence of an endoleak could be explained by hypoxia in the aortic wall.

A Scoping Review on the Incidence, Risk Factors, and Outcomes of Proximal Neck Dilatation after Standard and Complex Endovascular Repair for Abdominal Aortic Aneurysms

Background: To define proximal neck dilation (PND) after standard endovascular aneurysm repair (EVAR) and fenestrated EVAR (FEVAR), determining: incidence and risk factors; evidence base that links PND to outcomes of patients; recurring themes or gaps in the literature. Methods: We performed a scoping review and included only full-text English articles with follow-up focusing on PND in patients undergoing EVAR or FEVAR, published between 2000 and 2022. The following PICO question was used to build the search equation: in patients with abdominal-aortic-aneurysm (AAA) (Population) undergoing endovascular repair (Intervention), what are the incidence, risk factors and prognosis of radiologically defined PND (Comparison) on short-term and long-term outcomes (Outcomes)? Results: 15 articles were included after review. Measurement protocols for proximal aortic neck (PAN) varied among individual studies and the definition of PND resulted as heterogeneous. Rate of patients with a PND ranged between 0% and 41%. Large proximal neck (>28 mm) and excessive graft sizing (30%) were predictors for PND. New endografts with low outward radial forces and FEVAR seemed to be protective. Surgical conversion was the definitive option in the case of patients unfit for other endovascular treatments. Conclusions: PND is a frequent finding after EVAR and FEVAR. Excessive graft oversizing and large baseline PAN were predictors of neck enlargement, independently by the type of standard endograft used. FEVAR may be considered protective against complications, together with endografts using low outward radial forces. Lifelong radiological follow-up is mandatory.

DANCER: Study protocol of a prospective, non-randomized controlled trial for crossed limb versus standard limb configuration in endovascular abdominal aortic aneurysm repair

Background

Hostile anatomy, especially severely angulated neck and tortuous iliac arteries, has always been a conundrum in endovascular aneurysm repair (EVAR). Crossed limb (CL) graft, also called the “ballerina technique,” has been utilized to address this problem by facilitating gate cannulation. In terms of short and long-term outcomes, correlated studies have made inconsistent conclusions and this issue remains controversial. Based on a previous cohort study conducted in our center, we aim to prospectively compare the safety and efficacy between CL and standard limb (SL) configuration in patients receiving EVAR.

Methods

This is a prospective, single-center, non-randomized controlled trial. A total of 275 patients who meet the inclusion criteria will be enrolled and allocated with a 4:11 ratio of CL to SL, which is based on results of our previous study. All patients will receive same perioperative management and postoperative medications. All EVAR procedures will be performed under standard protocol, utilizing Endurant II or IIs Stent Graft. The configuration of the graft stent will be decided by surgeons and confirmed by final angiography. The primary outcome is 3-year freedom from major adverse limb-graft events (MALEs). Endpoints will be assessed at the following time points: 1, 6, 12, 24, and 36 months.

Discussion

To our best knowledge, this crosseD vs. stANdard Configuration in Endovascular Repair (DANCER) trial is the first non-randomized controlled trial to compare these two graft configurations in EVAR. The main aim is to compare the MALEs between two groups at 3 years postoperatively. This trial will hopefully provide high-level evidence for employing CL in EVAR.

Clinical trial registration

[www.chictr.org.cn], identifier [ChiCTR2100053055].

Infrarenal Remains Infrarenal-EVAR Suitability of Small AAA Is Rarely Compromised despite Morphological Changes during Surveillance

The aim was to analyze small abdominal aortic aneurysm (AAA) morphology during surveillance with regard to standard endovascular aortic repair (EVAR) suitability. This retrospective single-center study included all patients (n = 52, 48 male, 70 ± 8 years) with asymptomatic AAA ≤ 5.4 cm undergoing ≥2 computed tomography angiography(CTA)/magnetic resonance imaging (MRI) studies (interval: ≥6 months) between 2010 and 2018. Aneurysm diameter, neck quality (shape, length, angulation, thrombus/calcification), aneurysm thrombus, and distal landing zone diameters were compared between first and last CTA/MRI. Resulting treatment plan changes were determined. Neck shortening occurred in 25 AAA (mean rate: 2.0 ± 4.2 mm/year). Neck thrombus, present in 31 patients initially, increased in 16. Average AAA diameters were 47.7 ± 9.3 mm and 56.3 ± 11.6 mm on first and last CTA/MRI, mean aneurysm growth rate was 4.2 mm/year. Aneurysm thrombus was present in 46 patients primarily, increasing in 32. Neck thrombus growth and neck length change, aneurysm thrombus amount and aneurysm growth and aneurysm growth and neck angulation were significantly correlated. A total of 46 (88%) patients underwent open (12/46) or endovascular (34/46) surgery. The planned procedure changed from EVAR to fenestrated EVAR in two patients and from double to triple fenestrated EVAR in one. Thus, standard EVAR suitability was predominantly maintained as the threshold diameter for surgery was reached despite morphological changes. Consecutively, a possibly different pathogenesis of infra- versus suprarenal AAA merits further investigation.

Predictors of Abdominal Aortic Aneurysm Shrinkage after Endovascular Repair

Recent studies demonstrate that patients with a shrinking abdominal aortic aneurysm (AAA), one-year after endovascular repair (EVAR), have better long-term outcomes than patients with a stable AAA. It is not known what factors determine whether an AAA will shrink or not. In this study, a range of parameters was investigated to identify their use in differentiating patients that will develop a shrinking AAA from those with a stable AAA one-year after EVAR. Hundred-seventy-four patients (67 shrinking AAA, 107 stable AAA) who underwent elective, infrarenal EVAR were enrolled between 2011-2018. Long-term survival was significantly better in patients with a shrinking AAA, compared to those with a stable AAA (p = 0.038). Larger preoperative maximum AAA diameter was associated with an increased likelihood of developing AAA shrinkage one-year after EVAR-whereas older age and larger preoperative infrarenal β angle were associated with a reduced likelihood of AAA shrinkage. However, this multivariate logistic regression model was only able to correctly identify 66.7% of patients with AAA shrinkage from the total cohort. This is not sufficient for implementation in clinical care, and therefore future research is recommended to dive deeper into AAA anatomy, and explore potential predictors using artificial intelligence and radiomics.