A morphovolumetric analysis of aneurysm sac evolution after elective endovascular abdominal aortic repair

Fenestrated Endovascular Aortic Aneurysm Repair Is Associated with Increased Sac Regression on Postoperative Volumetric Analysis Compared to Endovascular Aortic Aneurysm Repair

BACKGROUND

Endovascular aortic aneurysm repair (EVAR) is utilized to treat abdominal aortic aneurysms, while patients with short infrarenal necks can undergo fenestrated EVAR (FEVAR). Previous studies have demonstrated decreased aortic neck dilation for FEVAR compared to EVAR. Sac regression is a marker of success after EVAR; however, little is known regarding changes in sac volumetrics. This study compares aortic sac regression after EVAR versus FEVAR using volumetric analysis.

METHODS

A retrospective review of prospectively collected data from 120 patients who underwent EVAR was performed. Thirty patients underwent FEVAR (Cook Medical Inc, Bloomington, IN) and 90 patients underwent EVAR (30 each with Endurant [Medtronic, Dublin, Ireland], Excluder [Gore, Flagstaff, AZ], and Zenith [Cook]). Demographic data were analyzed. Using 3-dimensional reconstruction software, preoperative and postoperative aneurysm sac volumes were measured, in addition to aneurysm characteristics.

RESULTS

There were no differences in demographic or preoperative comorbidities. Preoperatively, FEVAR had greater percentage of thrombus within the sac by volume compared to EVAR (51.5% vs. 39.1%, P = 0.0002), and greater overall sac volume (240.8 ± 100.4 vs. 188.2 ± 82.4 cm3, P = 0.005). EVAR patients had greater number of lumbar arteries (7.26 ± 1.68 vs. 5.31 ± 1.93, P < 0.000001). On postoperative follow-up, FEVAR cases had greater sac regression compared to standard EVAR (-22.75 ± 25.7% vs. -5.98 ± 19.66%, P = 0.00031). The percentage of sac regression was greater when measured by volume compared to maximum diameter for FEVAR (-22.75 ± 25.7% vs. -13.90 ± 15.4%, P = 0.01) but not EVAR (-5.98 ± 19.7% vs. -4.51 ± 15.2%, P = 0.246). Those in the top tertile of percent volume of thrombus (>48.5%) were more likely to experience greater than 10% sac regression by volume (55% vs. 33.3%, P = 0.015). On multivariate analysis, FEVAR was associated with sac regression greater than 10% by volume (odds ratio [OR] 4.325, 95% confidence interval [CI] 1.346-13.901, P = 0.014), while endoleak (OR 0.162, 95% CI 0.055-0.479, P < 0.001) and 2 patent hypogastric arteries (OR 0.066, 95% CI 0.005-0.904, P = 0.042) were predictive against.

CONCLUSIONS

Fenestrated EVAR is associated with greater sac regression compared to EVAR on volumetric analysis. This difference may be attributable to decreased endotension within the aneurysm resulting from less aortic neck dilatation, while the greater proportion of thrombus may be a protective factor from growth. Patients being evaluated for EVAR with borderline neck anatomy should be considered for FEVAR given increased sac regression.

Outcome Analysis of Pre-Emptive Embolization of the Collateral Branches of the Abdominal Aorta During Standard Infrarenal Endovascular Aortic Repair

Objectives: To report the results of pre-emptive embolization of collateral branches of the abdominal aorta in patients undergoing standard bifurcated EVAR versus those undergoing standard EVAR without embolization. Methods: This study is a single-center, retrospective, observational cohort analysis of consecutive patients who underwent elective standard endovascular aneurysm repair (EVAR) between 1 October 2013, and 31 December 2022, with a minimum follow-up period of 2 years. The patients were divided into two groups: group A, which did not receive embolization, and group B, which underwent pre-emptive embolization of aortic collateral branches. The primary outcomes for this study include overall survival, freedom from aorta-related mortality (ARM), and freedom from reinterventions related to type 2 endoleak (T2E). In cases of multiple reinterventions, only the first one was considered for this analysis. The secondary outcome focused on assessing freedom from aneurysm sac enlargement. Results: We analyzed a total of 265 endovascular aneurysm repairs (EVARs): 183 (69.1%) were classified into group A, and 82 (30.9%) into group B. The median follow-up duration was 48 months [interquartile range (IQR), 28-65.5], which was not significantly different between the two groups [45 months (26-63) in group A vs. 52.5 months (29.5-72.5) in group B, p = 0.098]. The estimated cumulative survival rates were 87% (0.2) at 2 years (95% confidence interval [CI]: 82.6-92.9) and 67% (0.3) at 5 years (95% CI: 60.3-73.1), with no significant difference between the groups (p = 0.263). The aorta-related mortality rate was 1.1% (n = 3); all instances occurred following open conversion due to graft infection (n = 2) and in one case of secondary aortic rupture (n = 1). In total, 34 cases (12.8%) indicated a secondary intervention related to type 2 endoleak (T2E). The freedom from T2E-related reintervention rate was 99% (0.01) at 2 years (95% CI: 99.4-99.8) and 88% (0.3) at 5 years (95% CI: 81.4-92.5), with no differences between the groups (p = 0.282). Cox regression analysis revealed that age over 80 years is an independent negative predictor of survival, with a hazard ratio (HR) of 3.5 (95% confidence interval [CI]: 2.27-5.50; p < 0.001). Additionally, T2E-related reintervention was identified as a negative predictor, with an HR of 2.4 (95% CI: 1.05-5.54; p = 0.037). In this study, conversion to open repair was necessary for 14 patients (5.3%), with three conversions occurring due to rupture; however, T2E was not a determining factor in any of these conversions. At the last available follow-up computed tomography angiography (CT-A), the median aneurysm diameter was significantly lower in group B, measuring 44 mm (range 37.7-50), compared to group A, measuring 48 mm (range 39-57.5) (p < 0.001). Both groups showed a significant change from baseline measurements (p = 0.001). Conclusions: Pre-emptive embolization of the aortic collateral branches does not lead to improved aorta-related outcomes after EVAR.

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.

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.

The Role of Aortic Volume in the Natural History of Abdominal Aortic Aneurysms and Post-Endovascular Aortic Aneurysm Repair Surveillance

There has been a debate about whether maximum diameter can be solely used to assess the natural history of abdominal aortic aneurysm. The aim of the present review is to collect all the available evidence on the role of abdominal aortic aneurysm (AAA) volume in the natural history of AAAs, including small untreated AAAs and AAAs treated by EVAR. The current literature appears to reinforce the role of volume as a supplementary measure for evaluating the natural history of AAA, in both intact AAAs and after EVAR. The clinical impact of AAA volume measurements remains unclear. Several studies show that volumetric analysis can assess changes in AAAs and predict successful endoluminal exclusion after EVAR more accurately than diameter. However, most studies lack strict standardized measurement criteria and well-defined outcome definitions. It remains unclear whether volumetry could replace diameter assessment in defining the risk of rupture of AAAs and identifying clinically relevant sac growth.

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.

Abdominal Aortic Aneurysm Diameter versus Volume: A Systematic Review

Recently, AAA volume measurement has been proposed as a potentially valuable surveillance method in situations when diameter measurement might fail.

OBJECTIVE

The aim of this systematic review was to analyze the results of previous studies comparing AAA diameter and volume measurements.

METHODS

A systematic search in PubMed, Cochrane, and EMBASE databases was performed to identify studies investigating the use of diameter and volume measurements in AAA diagnosis and prognosis in English, German, and Russian, published until December 2022. The manuscripts were reviewed by three researchers and scored on the quality of the research using MINORS criteria.

RESULTS

After screening 752 manuscripts, 19 studies (n = 1690) were included. The majority (n = 17) of the manuscripts appeared to favor volume. It is, however, important to highlight the heterogeneity of methodologies and lack of standardized protocol for measuring both volume and diameter in the included studies, which hindered the interpretation of the results.

CONCLUSIONS

The clinical relevance of abdominal aortic aneurysm volume measurement is still unclear, although studies show favorable and promising results for volumetric changes in AAA, especially in follow-up after EVAR.

Volumetric analysis of effectiveness of embolization for preventing type II endoleaks following endovascular aortic aneurysm repair

OBJECTIVE

The presence of endoleak was associated with the failure of endovascular aortic aneurysm repair (EVAR) treatment. The key to eliminating type II endoleak has shifted from reintervention to prevention. This study aimed to evaluate the effectiveness and safety of applying fibrin sealant to prevent type II endoleak in conjunction with EVAR.

METHODS

All patients with abdominal aortic aneurysm who underwent EVAR from June 2019 to July 2021 were reviewed. Patients were grouped as Group A: standard EVAR with preemptive embolization and Group B: standard EVAR alone. The primary endpoint was the incidence of type II endoleak. The secondary endpoints were aneurysm sac regression, the inferior mesenteric artery patency, the numbers of patent lumbar arteries, and all-cause mortality.

RESULTS

A total of 104 patients were included in Group A, and 116 were included in Group B. Technical success rate was 100%. The overall incidence of type II endoleak in Group A was significantly lower than that in Group B (4.8% vs 19.0%). The mean time of freedom from type II endoleak was 22.71 months for Group A (95% confidence interval, 21.59-23.83 months) and 19.89 months for Group B (95% confidence interval, 18.08-21.70 months). The Kaplan-Meier estimate of freedom from type II endoleak showed a significantly longer duration of freedom from type II endoleak in Group A (81.0% vs 95.2%). Group A showed a continuous sac regression tendency. In Group B, the sac volume decreased within 12 months but increased by 3.07 cm³ at 24 months. No complications were noted in both groups.

CONCLUSIONS

Nonselective preemptive embolization with porcine fibrin sealant during EVAR was safe and effective in preventing type II endoleak in the short and mid-term. Preemptive embolization can lead to a significantly higher sac regression rate. Larger patient populations and longer follow-ups with randomized control designed trials are expected to verify the long-term effectiveness and safety of preemptive embolization in preventing type II endoleak.

Biomechanics and Early Sac Regression after Endovascular Aneurysm Repair of Abdominal Aortic Aneurysm

Background

Sac regression after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAA) is regarded as a marker of successful response to treatment. Several factors influence sac behavior after EVAR, yet little is known about the value of preoperative biomechanics. The aim of this study was to investigate the difference in aortic biomechanics between patients with and without sac regression.

Methods

Patients treated with standard EVAR for infrarenal AAA at the Karolinska University Hospital between 2009 and 2012 with one preoperative and a minimum of two postoperative computed tomography angiography (CTA) scans were considered for inclusion in this single-center retrospective cohort study. Biomechanical indices such as AAA wall stress and wall stress-strength ratio as well as intraluminal thrombus (ILT) thickness and stress were measured preoperatively in A4ClinicRE (VASCOPS GmbH). AAA diameter and volume were analyzed on preoperative, 30-day, and 1-year CTAs. Patients were dichotomized based on sac regression, defined as a ≥ 5 mm decrease in maximal AAA diameter between the first two postoperative CTA scans. Multivariable logistic regression was used for analysis of factors associated with early sac regression.

Results

Of the 101 patients treated during the inclusion period, 64 were included. Thirty-nine (61%) demonstrated sac regression and 25 (39%) had a stable sac or sac increase. The mean patients age (73 years vs 76 years), male sex (85% vs 96%), and median AAA diameter (58 mm vs 58.5 mm) did not differ between patients with and without sac regression. Although no difference in preoperative biomechanics was seen between the groups, multivariable logistic regression revealed that a larger AAA diameter (odds ratio [OR], 1.27; 95% confidence interval [CI], 1.06-1.51; P = .009) and smoking (OR, 22.1; 95% CI, 2.78-174; P = .003) were positively associated with sac regression. In contrast, the lumen diameter (OR, 0.87; 95% CI, 0.77-0.98; P = .023), ILT thickness (OR, 0.85; 95% CI, 0.75-0.97; P = .013), aspirin or direct-acting oral anticoagulant use (OR, 0.11; 95% CI, 0.02-0.61; P = .012), and mean ILT stress (OR, 0.35; 95% CI, 0.14-0.87; P = .024) showed a negative association. Patients with sac regression had fewer reinterventions (log-rank P = .010) and lower mortality (log-rank P = .012) at the 5-year follow-up.

Conclusions

This study, characterizing preoperative biomechanics in patients with and without sac regression, demonstrated a negative association between mean ILT stress and ILT thickness with a change in sac diameter after EVAR. Given that the ILT is a highly dynamic entity, further studies focusing on the role of the thrombus are needed. Furthermore, patients presenting with early sac regression had improved outcomes after EVAR.