One-year aneurysm-sac dynamics are associated with reinterventions and rupture following infrarenal endovascular aneurysm repair

Beyond Endovascular Solutions: Open Sac Revision with Graft Preservation for Persistent Aortic Sac Expansion Post-EVAR

BACKGROUND

Aortic sac expansion after endovascular aortic aneurysm repair (EVAR) is associated with higher reintervention rates, late rupture, and long-term all-cause mortality. Endovascular options have limitations, and guidelines recommend open sac revision (OSR) if these fail. This study reviews the technique, indications, and outcomes for OSR following EVAR at Auckland City Hospital.

METHODS

We identified all OSR cases with stent-graft preservation for aortic sac expansion post-EVAR at Auckland City Hospital from January 2010 to October 2023. Techniques included sac closure, plication, or omental wrapping. Cases involving infected grafts were excluded.

RESULTS

Seventeen patients (median age: 82 years, predominantly male) underwent OSR, with a median follow-up of 3 years. The primary indication was sac expansion with type 2 endoleak in 88.24% of patients, while 2 cases were type V endoleaks. Intraoperatively, endoleaks were found in 94.12% of patients, with 88.24% having type 2 endoleak and 17.65% having type 3 endoleaks. Omentoplasty was performed in 58.82% of cases. Although not statistically significant, there was a trend toward lower endoleak recurrence with omentoplasty than sac closure. Reintervention for progressive sac expansion was required in 17.65% of patients (3/17), with 2 additional patients (11.76%) monitored for recurrent endoleak without further intervention. All patients were discharged, with 82.35% going home without needing rehabilitation. The median hospital stay was 7 days, and the 30-day mortality rate was 0%.

CONCLUSION

OSR with graft preservation is effective for sac expansion post-EVAR, facilitating endoleak identification and repair while avoiding aortic clamping. Ongoing surveillance is necessary.

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.

Volume Measurements for Surveillance after Endovascular Aneurysm Repair using Artificial Intelligence

OBJECTIVE

Surveillance after endovascular aneurysm repair (EVAR) is suboptimal due to limited compliance and relatively large variability in measurement methods of abdominal aortic aneurysm (AAA) sac size after treatment. Measuring volume offers a more sensitive early indicator of aneurysm sac growth or regression and stability, but is more time consuming and thus less practical than measuring maximum diameter. This study evaluated the accuracy and consistency of the artificial intelligence (AI) driven software PRAEVAorta 2 and compared it with an established semi-automated segmentation method.

METHODS

Post-EVAR aneurysm sac volumes measured by AI were compared with a semi-automated segmentation method (3mensio software) in patients with an infrarenal AAA, focusing on absolute aneurysm volume and volume evolution over time. The clinical impact of both methods was evaluated by categorising patients as showing either AAA sac regression, stabilisation, or growth comparing the 30 day and one year post-EVAR computed tomography angiography (CTA) images. Inter- and intra-method agreement were assessed using Bland-Altman analysis, the intraclass correlation coefficient (ICC), and Cohen's κ statistic.

RESULTS

Forty nine patients (98 CTA images) were analysed, after excluding 15 patients due to segmentation errors by AI owing to low quality CT scans. Aneurysm sac volume measurements showed excellent correlation (ICC = 0.94, 95% confidence interval [CI] 0.88 - 0.99) with good to excellent correlation for volume evolution over time (ICC = 0.85, 95% CI 0.75 - 0.91). Categorisation of AAA sac evolution showed fair correlation (Cohen's κ = 0.33), with 12 discrepancies (24%) between methods. The intra-method agreement for the AI software demonstrated perfect consistency (bias = -0.01 cc), indicating that it is more reliable compared with the semi-automated method.

CONCLUSION

Despite some differences in AAA sac volume measurements, the highly consistent AI driven software accurately measured AAA sac volume evolution. AAA sac evolution classification appears to be more reliable than existing methods and may therefore improve risk stratification post-EVAR, and could facilitate AI driven personalised surveillance programmes. While high quality CTA images are crucial, considering radiation exposure is important, validating the software with non-contrast CT scans might reduce the radiation burden.

Proprotein convertase subtilisin/kexin type 9 as a drug target for abdominal aortic aneurysm

PURPOSE OF REVIEW

There are no current drug therapies to limit abdominal aortic aneurysm (AAA) growth. This review summarizes evidence suggesting that inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) may be a drug target to limit AAA growth.

RECENT FINDINGS

Mendelian randomization studies suggest that raised LDL and non-HDL-cholesterol are causal in AAA formation. PCSK9 was reported to be upregulated in human AAA samples compared to aortic samples from organ donors. PCSK9 gain of function viral vectors promoted aortic expansion in C57BL/6 mice infused with angiotensin II. The effect of altering PCSK9 expression in the aortic perfusion elastase model was reported to be inconsistent. Mutations in the gene encoding PCSK9, which increase serum cholesterol, were associated with increased risk of human AAA. Patients with AAA also have a high risk of cardiovascular death, myocardial infarction and stroke. Recent research suggests that PCSK9 inhibition would substantially reduce the risk of these events.

SUMMARY

Past research suggests that drugs that inhibit PCSK9 have potential as a novel therapy for AAA to both limit aneurysm growth and reduce risk of cardiovascular events. A large multinational randomized controlled trial is needed to test if PCSK9 inhibition limits AAA growth and cardiovascular events.

Long Term Outcomes of the Gore Excluder Low Permeability Endoprosthesis for the Treatment of Infrarenal Aortic Aneurysms

OBJECTIVE

This study evaluated the long term outcomes of endovascular aneurysm repair using the Gore Excluder Low Permeability (LP) endoprosthesis across high volume Dutch hospitals.

METHODS

A retrospective analysis was conducted of patients treated with the Excluder LP for infrarenal abdominal aortic aneurysm (AAA) in four hospitals between 2004 and 2017. Primary outcomes were overall survival, freedom from re-interventions (overall, inside and outside instructions for use, IFU), and AAA sac dynamics: growth (> 5 mm), stabilisation, and regression (< 5 mm). Secondary outcomes were technical success (device deployment), procedural parameters, and re-interventions. Follow up visits were extracted from patient files, with imaging assessed for complications and AAA diameter.

RESULTS

Five hundred and fourteen patients were enrolled, with a median (IQR) follow up of 5.0 (2.9, 6.9) years. Survival rates were 94.0% at one year, 73.0% at five years, and 37.0% at 10 years, with freedom from re-interventions of 89.0%, 79.0%, and 71.0%, respectively. 37.9% were treated outside IFU, leading to significantly more re-interventions over 10 years compared with those treated inside IFU (36.0% vs. 25.0%, respectively; p = .044). The aneurysm sac regressed by 53.5% at one year, 65.8% at five years, and 77.8% at 10 years, and grew by 9.8%, 14.3%, and 22.2%, respectively. Patients with one year sac growth had significantly worse survival (p = .047). Seven patients (1.4%) had a ruptured aneurysm during follow up. Over 15 years, type 1a endoleak occurred in 5.3%, type 1b in 3.1%, type 3 in 1.9%, type 4 in 0.2%, and type 2 in 35.6% of patients.

CONCLUSION

This multicentre study of real world endovascular aneurysm repair data using the Gore Excluder LP endoprosthesis demonstrated robust long term survival and re-intervention rates, despite 37.9% of patients being treated outside IFU, with type 4 endoleak being rare. Treatment outside IFU significantly increased re-intervention rates and one year sac growth was associated with statistically significantly worse survival.

Implications of preoperative arterial stiffness for patients treated with endovascular repair of abdominal aortic aneurysms

Arterial stiffening is associated with adverse cardiovascular patient outcomes; stiffness may also be associated with postsurgical events and has been suggested to be a fundamental mechanism in the pathogenesis of aortic aneurysms. Although open repair of aneurysms decreases aortic stiffness, implantation of a rigid endograft is associated with increased aortic stiffness after endovascular aneurysm repair (EVAR). This review provides an overview of aortic wall physiology and the contemporary understanding of aortic stiffness and its implications for patients undergoing abdominal aortic aneurysm repair. Recent data suggests that increased central arterial stiffness, estimated preoperatively using the pulse wave velocity (PWV), may predict aneurysm sac behavior after EVAR, with elevated preoperative PWV associated with less sac shrinkage, and even sac enlargement, after EVAR. With the development of several simple noninvasive methods to measure PWV, such as brachial-ankle PWV and single cuff brachial oscillometry, there may be a role for monitoring ambulatory PWV to predict outcomes after EVAR. Additionally, because aortic stiffness is associated with adverse cardiovascular outcomes, and EVAR increases aortic stiffness, assessment of aortic stiffness before aortic interventions may help to guide therapeutic decisions as well as surveillance protocols, leading to optimized patient outcomes.

One-year follow-up after active aortic aneurysm sac treatment with shape memory polymer devices during endovascular aneurysm repair

OBJECTIVE

To determine the safety and efficacy of treating abdominal aortic aneurysm (AAA) sacs with polyurethane shape memory polymer (SMP) devices during endovascular aneurysm repair (EVAR), using a technique to fully treat the target lumen after endograft placement (aortic flow volume minus the endograft volume). SMP devices self-expand in the sac to form a porous scaffold that supports thrombosis throughout its structure.

METHODS

Two identical prospective, multicenter, single-arm studies were conducted in New Zealand and the Netherlands. The study population was adult candidates for elective EVAR of an infrarenal AAA (diameter of ≥55 mm in men and ≥50 mm in women). Key exclusion criteria were an inability to adequately seal a common iliac artery aneurysm, patent sac feeding vessels of >4 mm, and a target lumen volume of <20 mL or >135 mL. Target lumen volumes were estimated by subtracting endograft volumes from preprocedural imaging-based flow lumen volumes. SMP devices were delivered immediately after endograft deployment via a 6F sheath jailed in a bowed position in the sac. The primary efficacy end point was technical success, defined as filling the actual target lumen volume with fully expanded SMP at the completion of the procedure. Secondary efficacy outcome measures during follow-up were the change in sac volume and diameter, rate of type II endoleak and type I or III endoleaks, and the rate of open repair and related reinterventions, with data collection at 30 days, 6 months, and 1 year (to date). Baseline sac volumes and diameters for change in sac size analyses were determined from 30-day imaging studies. Baseline and follow-up volumes were normalized by subtraction of the endograft volume.

RESULTS

Of 34 patients treated with SMP devices and followed per protocol, 33 patients were evaluable at 1 year. Preprocedural aneurysm volume was 181.4 mL (95% confidence interval [CI], 150.7-212.1 mL) and preprocedural aneurysm diameter was 60.8 mm (95% CI, 57.8-63.9 mm). The target lumen volume was 56.3 mL (95% CI, 46.9-65.8 mL). Technical success was 100% and the ratio of SMP fully expanded volume to estimated target lumen volume was 1.4 ± 0.3. Baseline normalized sac volume and diameter were 140.7 mL (95% CI, 126.6-154.9 mL) and 61.0 mm (95% CI, 59.7-62.3 mm). The adjusted mean percentage change in normalized volume at 1 year was -28.8% (95% CI, -35.3 to -22.3%; P < .001). The adjusted mean change in sac diameter at 1 year was -5.9 mm (95% CI, -7.5 to -4.4 mm; P < .001). At 1 year, 81.8% of patients (95% CI, 64.5%-93.0%) achieved a ≥10% decrease in normalized volume and 57.6% of patients (95% CI, 39.2%-74.5%) achieved a ≥5 mm decrease in diameter. No device- or study procedure-related major adverse events occurred through 1 year after the procedure.

CONCLUSIONS

Treatment of AAA sacs with SMP devices during EVAR resulted in significant sac volume and diameter regression at 1 year with an acceptable safety profile in this prospective study.