Large Diameter (≥29 mm) Proximal Aortic Necks Are Associated with Increased Complication Rates after Endovascular Repair for Abdominal Aortic Aneurysm

Machine Learning Based Prediction of Post-operative Infrarenal Endograft Apposition for Abdominal Aortic Aneurysms

OBJECTIVE

Challenging infrarenal aortic neck characteristics have been associated with an increased risk of type Ia endoleak after endovascular aneurysm repair (EVAR). Short apposition (< 10 mm circumferential shortest apposition length [SAL]) on the first post-operative computed tomography angiography (CTA) has been associated with type Ia endoleak. Therefore, this study aimed to develop a model to predict post-operative SAL in patients with an abdominal aortic aneurysm based on the pre-operative shape.

METHODS

A statistical shape model was developed to obtain principal component scores. The dataset comprised patients treated by standard EVAR without complications (n = 93) enriched with patients with a late type Ia endoleak (n = 54). The infrarenal SAL was obtained from the first post-operative CTA and subsequently binarised (< 10 mm and ≥ 10 mm). The principal component scores that were statistically different between the SAL groups were used as input for five classification models, and evaluated by means of leave one out cross validation. Area under the receiver operating characteristic curves (AUC), accuracy, sensitivity, and specificity were determined for each classification model.

RESULTS

Of the 147 patients, 24 patients had an infrarenal SAL < 10 mm and 123 patients had a SAL ≥ 10 mm. The gradient boosting model resulted in the highest AUC of 0.77. Using this model, 114 patients (77.6%) were correctly classified; sensitivity (< 10 mm apposition was correctly predicted) and specificity (≥ 10 mm apposition was correctly predicted) were 0.70 and 0.79 based on a threshold of 0.21, respectively.

CONCLUSION

A model was developed to predict which patients undergoing EVAR will achieve sufficient graft apposition (≥ 10 mm) in the infrarenal aortic neck based on a statistical shape model of pre-operative CTA data. This model can help vascular specialists during the planning phase to accurately identify patients who are unlikely to achieve sufficient apposition after standard EVAR.

Midterm outcomes of "wide neck" abdominal aortic aneurysm after open or endovascular repair in two European centers: a propensity score matching analysis

BACKGROUND

The aim of this study was to compare mid-term clinical and morphological outcomes in patients undergoing open (OR) and endovascular aortic repair (EVAR) with a proximal wide neck abdominal aortic aneurysm (WN-AAA).

METHODS

Between 2009 and 2014 data of all patients undergoing OR at IRCCS San Raffaele Hospital and EVAR at German Aortic Center Hamburg were retrospectively analyzed. Primary endpoints were aneurysm-related mortality at 5 years, reintervention, and overall mortality. Secondary endpoint was proximal neck enlargement. A 1:1 propensity score matching (PSM) was performed. Survival and freedom from AAA-related reintervention were investigated in matched OR and EVAR group by Kaplan-Meier analysis.

RESULTS

Of all OR performed at IRCCS San Raffaele Hospital 70 were found to have a proximal neck >28 mm (mean age: 69.8±7.2 years, 67 [95.71%] male); of all consecutive EVAR performed at German Aortic Center Hamburg, 52 required an endograft size of at least 32 mm (mean age of 73.1±8.7 years, 49 [94.2%] male). After PSM, the study cohort consisted of 30 OR and EVAR. One early mortality was registered in both groups (P=NS). Mid-term freedom from reintervention compared in OR and EVAR, with no statistically significant differences (P=0.979). Eight (15.4%) patients treated with EVAR developed a significant proximal diameter enlargement (≥3 mm) while only 1 (1.4%) patient in the OR group had the same evolution (P<0.01).

CONCLUSIONS

In WN-AAA neck enlargement is observed more frequently in patients undergoing EVAR, but reintervention rate was similar in the 2 groups, demonstrating that both options were safe and effective.

A Meta-Analysis of Mid-Term Outcomes of Endovascular Aneurysm Sealing

BACKGROUND-AIM

Several studies have been published showing conflicting results on the outcome after endovascular aneurysm sealing (EVAS). The aim of the present study is to conduct a systematic review and meta-analysis of published evidence to assess the efficacy of EVAS in the management of patients with abdominal aortic aneurysm (AAA).

METHODS

An electronic search of the English medical literature, from 2010 to March 2021, was conducted using MEDLINE, EMBASE, and Cochrane databases to find studies relevant to outcome after EVAS.

RESULTS

The final analysis included 12 articles published between 2011 and 2021, including 1440 patients. In total, 79.3% of the included patients underwent aneurysm treatment according to the instructions for use. Technical success was 98.8%. Overall, 30-day mortality was 1.3%. Procedure-related complications were reported in 4% of the cohort. During median follow-up of 28.1 months (range 9-72 months), the pooled estimate of endoleak type I, migration and reinterventions was 16% (95% confidence interval [CI]=7-25), 16% (95% CI=9-23), and 19% (95% CI=11-28), respectively. In a sub-analysis, 7 studies (703 patients) reported outcome with a mean follow-up of more than 2 years (range 24-72 months). In these studies, the pooled estimate of endoleak type I, migration, and reinterventions was 25% (95% CI=13-38), 22% (95% CI=19-26), and 27% (95% CI=21-33), respectively.

CONCLUSION

Patients who have been treated with EVAS are in high risk for reintervention especially beyond 2 years following implantation. Close surveillance for patients treated with EVAS is mandatory.

A review of current status of cell-based therapies for aortic aneurysms

An aortic aneurysm (AA) is defined as focal aortic dilation that occurs mainly with older age and with chronic inflammation associated with atherosclerosis. The aneurysmal wall is a complex inflammatory environment characterized by endothelial dysfunction, macrophage activation, vascular smooth muscle cell (VSMC) apoptosis, and the production of proinflammatory molecules and matrix metalloproteases (MMPs) secreted by infiltrated inflammatory cells such as macrophages, T and B cells, dendritic cells, neutrophils, mast cells, and natural killer cells. To date, a considerable number of studies have been conducted on stem cell research, and growing evidence indicates that inflammation and tissue repair can be controlled through the functions of stem/progenitor cells. This review summarizes current cell-based therapies for AA, involving mesenchymal stem cells, VSMCs, multilineage-differentiating stress-enduring cells, and anti-inflammatory M2 macrophages. These cells produce beneficial outcomes in AA treatment by modulating the inflammatory environment, including decreasing the activity of proinflammatory molecules and MMPs, increasing anti-inflammatory molecules, modulating VSMC phenotypes, and preserving elastin. This article also describes detailed studies on pathophysiological mechanisms and the current progress of clinical trials.

A Statistical Shape Model of Infrarenal Aortic Necks in Patients With and Without Late Type Ia Endoleak After Endovascular Aneurysm Repair

PURPOSE

Hostile aortic neck characteristics, including short length, severe suprarenal and infrarenal angulation, conicity, and large diameter, have been associated with increased risk for type Ia endoleak (T1aEL) after endovascular aneurysm repair (EVAR). This study investigates the mid-term discriminative ability of a statistical shape model (SSM) of the infrarenal aortic neck morphology compared with or in combination with conventional measurements in patients who developed T1aEL post-EVAR.

MATERIALS AND METHODS

The dataset composed of EVAR patients who developed a T1aEL during follow-up and a control group without T1aEL. Principal component (PC) analysis was performed using a parametrization to create an SSM. Three logistic regression models were created. To discriminate between patients with and without T1aEL, sensitivity, specificity, and the area under the receiver operating characteristic (ROC) curve (AUC) were calculated.

RESULTS

In total, 126 patients (84% male) were included. Median follow-up time in T1aEl group and control group was 52 (31, 78.5) and 51 (40, 62.5) months, respectively. Median follow-up time was not statistically different between the groups (p=0.72). A statistically significant difference between the median PC scores of the T1aEL and control groups was found for the first, eighth, and ninth PC. Sensitivity, specificity, and AUC values for the SSM-based versus the conventional measurements-based logistic regression models were 79%, 70%, and 0.82 versus 74%, 73%, and 0.85, respectively. The model of the SSM and conventional measurements combined resulted in sensitivity, specificity, and AUC of 81%, 81%, and 0.92.

CONCLUSION

An SSM of the infrarenal aortic neck determines its 3-dimensional geometry. The SSM is a potential valuable tool for risk stratification and T1aEL prediction in EVAR. The SSM complements the conventional measurements of the individual preoperative infrarenal aortic neck geometry by increasing the predictive value for late type Ia endoleak after standard EVAR.

CLINICAL IMPACT

A statistical shape model (SSM) determines the 3-dimensional geometry of the infrarenal aortic neck. The SSM complements the conventional measurements of the individual pre-operative infrarenal aortic neck geometry by increasing the predictive value for late type Ia endoleaks post-EVAR. The SSM is a potential valuable tool for risk stratification and late T1aEL prediction in EVAR and it is a first step toward implementation of a treatment planning support tool in daily clinical practice.

Risk factors and adverse events related to supra- and infra-renal aortic dilation at twelve months after endovascular abdominal aortic aneurysm repair

BACKGROUND

Aortic remodeling and its effect on adverse events after endovascular abdominal aneurysm repair (EVAR) remain under investigation. This study aimed to assess aortic diameter alterations after EVAR, related risk factors and consequences to proximal sealing at 12 months.

METHODS

A single-center retrospective analysis of consecutive EVAR patients was undertaken. All patients underwent computed tomography angiography, preoperatively, at 1^st and 12^th month. The infrarenal diameter was measured just below the inferior renal artery, at 7 mm and 15 mm while the suprarenal, just above the superior renal artery (SRA), superior mesenteric artery (SMA) and just below the celiac trunk. Neck-related adverse events included migration and endoleak Ia.

RESULTS

A hundred fifty patients were included. At 1^st month, no significant diameter alteration was recorded at any level. At 12^th month, all infra-renal diameters increased (P<0.001) and diameters at SRA and SMA also augmented (P=0.024 and P=0.007, respectively). Neck diameter >29 mm, supra-renal fixation and oversizing >20% were associated to dilation at 12^th month. Neck adverse events were related to diameter alterations below the inferior renal artery (P=0.017), SRA (P=0.007) and SMA (P=0.05).

CONCLUSIONS

During the 12-month follow-up, aortic dilation may be detected from the supra-renal aorta to the total neck length. Neck dilation may be attributed to large neck diameter, supra-renal fixation, and aggressive oversizing. Neck-related adverse events are more common in patients with aortic dilation at 12 months.

Pre-operative Aortic Neck Characteristics and Post-operative Sealing Zone as Predictors of Type 1a Endoleak and Migration After Endovascular Aneurysm Repair: A Systematic Review and Meta-Analysis

OBJECTIVE

Establishing the predictive value of neck characteristics and real achieved sealing zone is essential to foster risk stratified procedure selection and imaging surveillance. This systematic review provides an overview of pre-operative aortic neck characteristics and post-operative real achieved sealing zone and their respective risk of type 1a endoleak and migration after endovascular aneurysm repair (EVAR).

METHODS

In agreement with PRISMA guidelines, MEDLINE, Embase, and Cochrane CENTRAL were searched. Data on neck characteristics, sealing zone, and EVAR outcome were extracted. Meta-analyses were performed to investigate the effect of neck diameter, angulation, and shape on type 1a endoleak (total, early ≤ 90 days, and late > 90 days) and migration in patients who underwent EVAR. A qualitative summary was also provided.

RESULTS

Thirty-three studies were included. Patients with a larger neck diameter had an increased risk of total type 1a endoleak (nine studies: OR 3.32, 95% CI 2.38 - 4.63), early type 1a endoleak (six studies: OR 2.64, 95% CI 1.27 - 5.48), late type 1a endoleak (six studies: OR 3.26, 95% CI 2.12 - 5.03), and migration (seven studies: OR 2.88, 95% CI 1.32 - 6.26). An angulated neck increased the risk of total type 1a endoleak (seven studies: OR 4.27, 95% CI 1.55 - 11.78) and late type 1a endoleak (seven studies: OR 5.56, 95% CI 2.19 - 14.13). Neck shape was not associated with type 1a endoleak. Neck length and real achieved sealing zone on post-EVAR computed tomography were identified as risk factors for type 1a endoleak and migration through qualitative summary.

CONCLUSION

There seems to be some consistent evidence that aortic neck diameter, angulation, and length are associated with the development of type 1a endoleak or migration. Real achieved sealing zone might be an important addition during follow up. However, a small number of studies, with serious limitations, could be included, and there was considerable variability in reporting patients and outcomes. A proposal for standardisation of aortic and EVAR data in future studies is provided.

The Ovation Alto platform: extending endovascular treatment beyond short-necked abdominal aortic aneurysms

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Is Evar Feasible in Challenging Aortic Neck Anatomies? A Technical Review and Ethical Discussion

Background: Endovascular aneurysm repair (EVAR) has become an accepted alternative to open repair (OR) for the treatment of abdominal aortic aneurysm (AAA) despite “hostile” anatomies that may reduce its effectiveness. Guidelines suggest refraining from EVAR in such circumstances, but in clinical practice, up to 44% of EVAR procedures are performed using stent grafts outside their instruction for use (IFU), with acceptable outcomes. Starting from this “inconsistency” between clinical practice and guidelines, the aim of this contribution is to report the technical results of the use of EVAR in challenging anatomies as well as the ethical aspects to identify the criteria by which the “best interest” of the patient can be set. Materials and Methods: A literature review on currently available evidence on standard EVAR using commercially available endografts in patients with hostile aortic neck anatomies was conducted. Medline using the PubMed interface and The Cochrane Library databases were searched from 1 January 2000 to 6 May 2021, considering the following outcomes: technical success; need for additional procedures; conversion to OR; reintervention; migration; the presence of type I endoleaks; AAA-related mortality rate. Results: A total of 52 publications were selected by the investigators for a detailed review. All studies were either prospective or retrospective observational studies reporting the immediate, 30-day, and/or follow-up outcomes of standard EVAR procedures in patients with challenging neck anatomies. No randomized trials were identified. Fourteen different endo-grafts systems were used in the selected studies. A total of 45 studies reported a technical success rate ranging from 93 to 100%, and 42 the need for additional procedures (mean value of 9.04%). Results at 30 days: the incidence rate of type Ia endoleak was reported by 37 studies with a mean value of 2.65%; 31 studies reported a null migration rate and 32 a null conversion rate to OR; in 31 of the 35 studies that reported AAA-related mortality, the incidence was null. Mid-term follow-up: the incidence rate of type Ia endoleak was reported by 48 studies with a mean value of 6.65%; 30 studies reported a null migration rate, 33 a null conversion rate to OR, and 28 of the 45 studies reported that the AAA-related mortality incidence was null. Conclusions: Based on the present analysis, EVAR appears to be a safe and effective procedure—and therefore recommendable—even in the presence of hostile anatomies, in patients deemed unfit for OR. However, in order to identify and pursue the patient’s best interest, particular attention must be paid to the management of the patient’s informed consent process, which—in addition to being an essential ethical-legal requirement to legitimize the medical act—ensures that clinical data can be integrated with the patient’s personal preferences and background, beyond the therapeutic potential of the proposed procedures and what is generically stated in the guidelines.

"Large Diameter" Aortic Endografts Are Associated With Aneurysm Sac Expansion

INTRODUCTION/OBJECTIVES

The purpose of this study was to evaluate the association between aortic endograft diameter and long-term outcomes following endovascular aneurysm repair (EVAR) performed in accordance with manufacturer instructions for use (IFU).

METHODS

Retrospective review of consecutive patients undergoing on-IFU EVAR (2000-2018) was performed to facilitate a comparative analysis of long-term patient outcomes based on device diameter. "Large diameter" devices were defined as >34mm. The primary outcome of interest was freedom from sac expansion throughout long-term follow-up. Analyses included standard bivariate analyses, Kaplan Meier with log-rank comparison, and Cox proportional hazards multivariate analysis.

RESULTS

A total of 1099 underwent on-IFU EVAR from 2000-2018. Follow-up data were available for 980 patients. Of these, 75 patients (7.6%) were treated with >34 mm devices. There were no significant differences in demographics or co-morbidities between the 2 groups, although pre-operative AAA size was greater in patients undergoing implantation of >34mm devices (58 ± 8.5 mm vs. 56 ± 17.4 mm; P=0.05). Median follow-up was 10.3 years. Patients with grafts >34 mm had reduced freedom from sac expansion throughout follow-up (P=0.038). There were no significant differences in reintervention rates, open conversion, or rupture when stratified by graft diameter. Multivariate Cox Regression identified patient age, pre-operative AAA size, need for reintervention, and use of >34 mm endografts as independent factors associated with expansion.

CONCLUSION

The use of large diameter aortic endografts is associated with higher rates of sac expansion during long-term follow-up. While there is undoubtedly a role for large diameter graft use in selected patients, it is important to recognize that these devices were typically approved post-hoc without the same regulatory scrutiny of smaller endografts. These findings underscore the importance of ongoing surveillance for patients treated with >34 mm grafts, irrespective of compliance with manufacturer IFU.

Risk assessment in aortic aneurysm repair by medical specialists versus the American College of Surgeons National Surgical Quality Improvement Program risk calculator outcomes

Objective

The aim of this online clinical vignette-based survey study was to compare risk assessments by vascular surgeons, anaesthesiologists and interventional radiologists involved in treating patients with aortic aneurysms in the Netherlands with the NSQIP risk calculator outcomes.

Methods

Participants, recruited using purposive sampling, provided their estimation of the likelihood of postoperative complications and events following aortic surgery in five fictional cases. These cases were subsequently scored using the NSQIP calculator. The risk assessments were statistically analysed using the ANOVA and student t-test.

Results

All participating specialists i.e. twelve vascular surgeons, ten interventional radiologists and ten anaesthesiologists completed the survey. In the vast majority of outcomes and vignettes, no significant differences were found between various specialists, whereas significant differences were found between the NSQIP risk calculator outcomes and the combined risk assessments of the specialists. Overall, specialist risk assessments differ from the NSQIP, but neither particularly higher nor lower compared to the risk calculator.

Conclusions

Risk assessment by vascular surgeons, anaesthesiologists and interventional radiologists differs significantly with NSQIP risk calculator outcomes, within the framework of both endovascular and open aortic aneurysm repair. Based on these results, implementing the NSQIP risk calculator in preoperative workup could be of added value in both patient planning as well as adequately informing patients for obtaining consent.

Ten-year single center experience in elective standard endovascular abdominal aortic aneurysm repair

BACKGROUND

Endovascular aneurysm repair (EVAR) has become the treatment of choice for abdominal aortic aneurysm (AAA), demonstrating excellent early outcomes. However, EVAR durability has been questioned in the long-term period. The aim of this study was to assess EVAR outcomes in terms of survival and freedom from re-intervention during a long-term period.

METHODS

All consecutive patients being treated, with elective standard EVAR, in a single tertiary center, were included between 2008 and 2018. Outcomes were defined as survival and freedom from re-intervention and were reported using Kaplan-Meyer lifetables. In subgroup analyses, sex, age (threshold at 65 and 80 years), neck diameter>28mm and type of fixation were also analyzed. Type of re-intervention and endoleak type I (ETIa) were also reported.

RESULTS

Five hundred and eight patients (94% males, mean age 72±7.3, mean AAA diameter 59±9mm) were included. The median follow-up was 3 years (range 0-10 years). The survival rate was 92.8% (SE 1.5%), 76.5% (SE 3.1%) and 41.6% (SE 6%), at 2, 5 and 10 years of follow-up, respectively. In total, 78 patients died; 8 deaths (8/75, 10%) were aneurysm related. In multivariate regression analysis, age (CI. 1.02-1.14; p=0.006) and ever tobacco use (CI. 1.02-6.12, P=0.045) were associated with the long-term mortality. Freedom from re-intervention was 96% (SE 1.1%), 93% (SE 1.8%), 85.5% (SE 5%) at 2, 5 and 9 years of follow-up. Limb occlusion was a common complication (n/n; 30% of re-intervention), particularly within the first 2 postoperative years. Six patients presented with rupture and were treated with open conversion. EVAR cases with supra-renal fixation graft presented lower rates of ETIa (CI. 76-87.27, P<0.001).

CONCLUSIONS

Elective standard EVAR is associated with good long-term survival showing low aneurysm-related mortality. Common risk factors such as advanced age and smoking are associated to higher mortality. The procedure presents low re-intervention rates, while limb occlusion is a complication presented within the first 2 postoperative years.

Systematic review and meta-analysis of endovascular abdominal aortic repair in large diameter infrarenal necks

OBJECTIVE

The aim of this study was to perform a meta-analysis of relevant published literature to investigate the impact of wide proximal aortic neck diameter on outcomes of endovascular aneurysm repair (EVAR) for the repair of abdominal aortic aneurysm (AAA).

METHODS

A systematic literature review was performed to examine the rate of clinical safety and effectiveness end points associated with wide proximal aortic neck diameter after EVAR for the treatment of AAA. A literature search was performed on August 9, 2019, using PubMed as the primary database and Cochrane as the secondary database. In all, there were 11 full articles included in the quantitative and qualitative analyses.

RESULTS

There was a total of 7448 patients who were treated for AAA with EVAR. Of these, 26.9% of patients were defined as having wide necks by the individual publications. The definition of wide neck varied in the literature and ranged from 25 mm or greater to 30 mm or greater. The percentage of male patients was 89.1% in the included articles. The mean or median age range was 72.7 to 76.5 years, which was similar for the wide and normal neck groups. Follow-up ranged from 2 to 5 years. Type I and Ia endoleaks occurred at a higher rate in the wide neck group compared with the normal neck group (11.3% vs 3.1%; P < .001). There was no difference in the rate of type Ib endoleaks between the wide and normal neck groups. The weighted averages of composite major adverse events and aneurysm-related mortality were all greater in the wide neck group (33.5% and 15.3%, respectively) compared with the normal neck group (21.2% and 3.9%, respectively) (P = .004).

CONCLUSIONS

The rates of type Ia endoleaks, reinterventions, and migrations were all significantly higher in the wide neck patient group compared with patients with normal aortic neck size through follow-up. The results of this literature review showed that, although EVAR for the treatment of AAA in patients with a wide aortic neck is feasible, there is a higher risk for complications, interventions, and mortality. In particular, type Ia endoleak is a risk, which could be mitigated by using proximal seal strategies.

Prognostic significance of large diameter proximal aortic neck in endovascular aneurysm repair

Background: Adverse morphological features of the proximal aortic neck have been identified as culprits for late failure after endovascular aneurysm repair (EVAR). Our objective was to investigate the prognostic role of wide proximal aortic neck in EVAR. Methods: We conducted a review of the literature in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify studies comparing outcomes of EVAR in patients with large versus small proximal aortic neck. A meta-analysis of time-to-event data was performed with the inverse-variance method and the results were reported as summary hazard ratio (HR) and 95 % CI. We applied random-effects models of meta-analysis. Results: We identified 9 observational studies reporting on a total of 7,682 patients (1,961 with large diameter and 5,721 with small diameter neck). The hazard of death (HR 1.57, 95 % CI 1.23-2.01; P = 0.0003), aneurysm-related reintervention (HR 2.06, 95 % CI 1.23-3.45; P = 0.006), type Ia endoleak (HR 6.69, 95 % CI 4.39-10.20; P < 0.001), sac expansion (HR 10.07, 95 % CI 1.80-56.53; P = 0.009), aneurysm rupture (HR 2.96, 95 % CI 2.00-4.38; P < 0.0001), and neck-related adverse events (HR 10.33, 95 % CI 4.95-21.56; P < 0.0001) was higher in patients with large diameter proximal aortic neck than in those with small neck. Conclusions: Patients with a large proximal aortic neck were found to have poorer outcomes than those with small neck. This finding has implications in decision making when selecting methods for aneurysm treatment and in EVAR surveillance for aneurysm-related complications in this cohort of patients.