Multicentre randomised controlled trial to evaluate the efficacy of pre-emptive inferior mesenteric artery embolisation during endovascular aortic aneurysm repair on aneurysm sac change: protocol of Clarify IMA study

Five-year follow-up of randomized clinical trial for pre-emptive inferior mesenteric artery embolization during endovascular aneurysm repair

OBJECTIVE

Type II endoleak (T2EL) is the most common type of endoleak after endovascular aneurysm repair (EVAR) and a common indication for reintervention due to late sac enlargement. Although pre-emptive embolization of the inferior mesenteric artery (IMA) has been proposed to prevent this, no studies have prospectively demonstrated its efficacy. This study aimed to prove the validity of IMA embolization during EVAR in selective cases by analyzing the mid-term outcomes of a randomized clinical trial (RCT).

METHODS

This single-center, parallel-group, non-blinded RCT included participants at high risk of T2EL, characterized by a patent IMA in conjunction with one or more following risk factors: a patent IMA ≥3 mm in diameter, lumbar arteries ≥2 mm in diameter, or an aortoiliac-type aneurysm. The participants were randomly assigned to two groups in a 1:1 ratio: one undergoing EVAR with IMA embolization and the other without. The primary endpoint was T2EL occurrence. The secondary endpoints included aneurysm sac changes and reintervention. In addition to RCT participants, outcomes of patients with low risk of T2EL were also analyzed.

RESULTS

The embolization and non-embolization groups each contained 53 patients. Five-year follow-up after the last patient enrollment revealed that T2ELs occurred in 28.3% and 54.7% of patients in the IMA embolization and non-embolization groups, respectively (P = .006). Both freedom from T2EL-related sac enlargement ≥5 mm and cumulative incidence of sac shrinkage ≥5 mm were significantly higher in the IMA embolization group than in the non-embolization group (95.5% vs 73.6% at 5 years; P = .021; 54.2% vs 33.6% at 5 years; P = .039, respectively). The freedom from T2EL-related sac enlargement ≥10 mm, an alternative indicator for T2EL-related reintervention, showed similar results (100% vs 90.4% at 5 years; P = .019). Outcomes in the low-risk group were preferable than those in the non-embolization group and comparable to those in the IMA embolization group.

CONCLUSIONS

A lower threshold for pre-emptive IMA embolization when implementing EVAR would be more appropriate if limited to patients at high risk of T2ELs.

Safety of preoperative branch embolization in patients undergoing evar

The purpose of this systematic review is to evaluate the safety of pre-endovascular abdominal aortic aneurysm repair (EVAR) embolization of aortic side branches - the inferior mesenteric artery and lumbar arteries. Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed. A search of MEDLINE and DIMENSION databases identified 9 studies published from 2011 to 2021 that satisfied the inclusion and exclusion criteria. These studies were analyzed to detect the incidence of embolization-related complications. A total of 482 patients underwent preoperative aortic side branch embolization, 30 (6.2%) of whom suffered some kind of minor complication. The only major complication observed was ischemic colitis in 4 (0.82%) patients, two (0.41%) of whom died after bowel resection surgery. Regarding these findings, aortic side branch embolization seems to be a safe procedure, with very low percentages of both minor and major complications.

Efficacy and safety of prophylactic intraoperative sac embolization in EVAR for abdominal aortic aneurysm: A meta-analysis

Objective

We aimed to investigate the effectiveness and safety of prophylactic sac embolization during endovascular aneurysm repair (EVAR) in patients suffering from abdominal aortic aneurysms.

Methods

We performed a systematic literature search of PubMed, Web of Science, EMbase, Cochrane Library, China National Knowledge Infrastructure (CNKI), VIP, Wanfang and China Biomedical Literature Database (CBM) to identify studies evaluating the outcomes of sac embolization vs. no embolization among patients who had received EVAR. The time limit of the search was from the establishing database to July 22, 2022. Outcome measures involved the type II endoleak rate, the other endoleak rate, the reintervention rate, mortality, and operation time. Fixed (no heterogeneity) or random effects models were constructed for each outcome. The outcomes are represented as the odds ratio (OR) with a 95% confidence interval (CI).

Results

Among the 2,622 studies screened, 13 studies involving 747 participants were included in the review. The incidence of early-term type II endoleak (OR = 0.2, 95% CI (0.13,0.31), P < 0.00001), mid-term type II endoleak (OR = 0.23, 95% CI (0.15,0.37), P < 0.00001), late-term type II endoleak (OR = 0.27, 95% CI (0.16,0.46), P < 0.00001) and reintervention (OR = 0.50, 95% CI (0.37,0.78), P = 0.002) within the sac embolization group were significantly lower than those in the non-embolization group. No significant differences were observed between the two groups were found for the other endoleak rates (OR = 0.67, 95% CI (0.34,1.32), P = 0.25), mortality (OR = 0.64, 95% CI (0.25,1.66), P = 0.36) and operation time operation (MD = 5.76, 95% CI (-8.30,19.83), P = 0.42).

Conclusions

EVAR combined with sac embolization effectively reduces the incidence of type II endoleak and the reintervention rate without enhancing the operation time. Therefore, more high-quality studies are still needed for validation due to the limited amount and quality of included literature.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022365648.

Preoperative predictive factors for type II endoleak: Trying to define high-risk patients

OBJECTIVE

Type 2 endoleaks (T2E) continue to be the "Achilles Heel" of endovascular aneurysm repair (EVAR). The aim of this study is to analyze preoperative factors of patients who underwent EVAR to define risk factors for T2E.

METHODS

From January 2015 to June 2020, 140 of 191 patients who underwent EVAR in our institution meet inclusion criteria for this study. Postoperative image control were performed using duplex ultrasound or CT scan. All T2E detected during follow-up were confirmed by angio CT. Preoperative anatomic and clinical variables were analyzed for T2E using t-test, Mann-Whitney U test and Fisher exact test. ROC curves and the corresponding area under the curve (AUC) were used to describe the predictive accuracy for endoleak.

RESULTS

T2E was detected in 16 patients (11.43%)0.12 of them (75%) were persistent and 10 (62.5%) provoked sac enlargement. Predictive factors for T2E were a greater IMA diameter (2.5 ± 0.5 vs. 3.3 ± 0.5, p < 0.001) and an increasing number of LA (4.8 ± 1.6 vs. 6.7 ± 1.4, p < 0.001). ROC curve analysis stablished thresholds of 3.5 mm for IMA diameter (sensitivity 77%, specificity 86%) and 5.5 for patent LA (sensitivity 88%, specificity 59%) as risk factor to develop T2E.

CONCLUSIONS

Preoperative aortic side branches embolization to avoid T2E is not still standarised. We tried to define a group of high-risk patients for T2E. According to our findings, patients with a preoperative IMA> 3 mm and more than 5 patent LA should be considered for pre-EVAR embolization.

Outcomes of embolization procedures for type II endoleaks following endovascular abdominal aortic repair

OBJECTIVE

The objective of this study was to investigate the mid-term outcomes of embolization procedures for type II endoleak after endovascular abdominal aortic repair, and clarify the risk factors for aneurysm enlargement after embolization procedures.

METHODS

This was a retrospective multicenter registry study enrolling patients who underwent embolization procedures for type II endoleaks after EVAR from January 2012 to December 2018 at 19 Japanese centers. The primary end point was the rate of freedom from aneurysm enlargement, more than 5 mm in the aortic maximum diameter, after an embolization procedure. Demographic, procedural, follow-up, and laboratory data were collected. Continuous variables were summarized descriptively, and Kaplan-Meier analyses and a Cox regression model were used for statistical analyses.

RESULTS

A total of 315 patients (248 men and 67 women) were enrolled. The average duration from the initial embolization procedure to the last follow-up was 31.6 ± 24.6 months. The rates of freedom from aneurysm enlargement at 3 and 5 years were 55.4 ± 3.8% and 37.0 ± 5.2%, respectively. A multivariate analysis revealed that a larger aortic diameter at the initial embolization procedure and the presence of a Moyamoya endoleak, defined as heterogeneous contrast opacity with an indistinct faint border, were associated with aneurysm enlargement after embolization management.

CONCLUSIONS

The embolization procedures were generally ineffective in preventing further expansion of abdominal aortic aneurysms in patients with type II endoleaks after EVAR, especially in patients with a large abdominal aortic aneurysm and/or a presence of a Moyamoya endoleak.

Long-term Outcomes of the Endurant and Excluder Stent Grafts for Endovascular Aneurysm Repair in a Japanese Cohort

PURPOSE

To compare the long-term outcomes of the most widely used third-generation stent grafts, the Endurant and Excluder stent grafts, in Japanese patients using a multicenter registry.

MATERIALS AND METHODS

A retrospective analysis of endovascular aneurysm repairs for abdominal aortic and iliac artery aneurysms using either the Endurant or the Excluder stent grafts from January 2012 to July 2019 at 10 Japanese hospitals was performed.

RESULTS

A total of 332 and 378 repairs using the Endurant and Excluder stent grafts, respectively, were analyzed. Although the patients' characteristics were generally similar in the two groups, the Endurant group exhibited significantly shorter (Endurant: 31.5±18.6 mm, Excluder: 37.4±21.0 mm; p<0.001), larger (Endurant: 22.4±4.2 mm, Excluder: 21.7±3.8 mm; p=0.029), and more reversed tapered (Endurant: 12.1%, Excluder: 5.8%; p=0.003) proximal necks. The incidence of instructions for use (IFU) violations was similar between the two groups (Endurant: 59.0%, Excluder: 54.5%; p=0.223). However, the Endurant group had significantly more proximal neck-related IFU violations (54.1% and 46.3%, respectively; p=0.039), more access-related IFU violations (8.1% and 4.0%, respectively; p=0.019), and fewer bilateral hypogastric artery embolizations (5.1% and 9.3%, respectively; p=0.035) compared with the Excluder group. The incidence of intraoperative (Endurant: 3.6%, Excluder: 3.7%; p=0.950) and perioperative complications (Endurant: 3.6%, Excluder: 3.4%, p=0.899) was equivalent in the two groups. However, there was a significantly higher incidence of postoperative type II endoleaks in the Excluder group (Endurant: 28%, Excluder: 46.0%, p<0.001). Aneurysm sac regression was more frequent in the Endurant group (Endurant: 40.7%, Excluder: 31.7%, p=0.013). The Endurant group also had significantly higher rates of sac increase (Endurant: 13.0%, Excluder: 7.7%, p=0.020). Kaplan-Meier curve and log-rank analyses revealed no statistical differences in late complications (p=0.868) and overall survival (p=0.926).

CONCLUSIONS

There were no statistically significant differences between the Endurant and the Excluder stent grafts in terms of intraoperative, perioperative, and late complication rates; however, the anatomical characteristics of the patients were significantly different.

Risk Analysis of Aneurysm Sac Enlargement Caused by Type II Endoleak after Endovascular Aortic Repair

BACKGROUND

Although the preoperative risk factors associated with the occurrence of type II endoleak (ETII) after endovascular aortic repair (EVAR) have gradually become more evident, the preoperative risk factors associated with aneurysm sac enlargement caused by ETII remain unclear. This study aimed to determine the preoperative risk factors associated with aneurysm sac enlargement caused by ETII after EVAR.

METHODS

This retrospective cohort study reviewed 519 EVARs performed for true abdominal aortic aneurysm between January 2006 and December 2018 at our institution. EVARs using commercially available bifurcated devices with no type I or III endoleaks during follow-up and with ≥12 months follow-up were included. A total of 320 patients were enrolled in the study. To identify the preoperative risk factors of sac enlargement after EVAR, Cox regression analysis was used to assess preoperative data.

RESULTS

The median follow-up period was 60.8 months. Overall, 135 of 320 patients (42%) had ETII during follow-up, and 47 of 135 patients (35%) developed aneurysm sac enlargement. Multivariate analysis revealed that chronic kidney disease (CKD) stage ≥4 (hazard ratio [HR], 4.65; 95% confidence interval [CI], 2.13-10.15; P = 0.001), patent inferior mesenteric artery (IMA) (HR, 17.85; 95% CI, 2.46-129.73; P< 0.001), and number of patent lumbar arteries (LAs) (HR, 1.37; 95% CI, 1.13-1.68; P= 0.002) were risk factors of aneurysm sac enlargement caused by ETII.

CONCLUSIONS

CKD stage ≥4, patent IMA, and number of patent LAs were independent risk factors for aneurysm sac enlargement after EVAR. In particular, patent IMA had the highest HR and seemed to have the greatest impact on long-term aneurysm sac enlargement. Hence, taking preoperative measures to address a patent IMA appears to be important in reducing the incidence of sac enlargement.

Outcomes of Preventive Embolization of the Inferior Mesenteric Artery during Endovascular Abdominal Aortic Aneurysm Repair

PURPOSE

To evaluate the impact of preemptive inferior mesenteric artery (IMA) embolization on outcomes of endovascular abdominal aortic aneurysm (AAA) repair (EVAR).

MATERIALS AND METHODS

From January 2015 to July 2017, all patients undergoing elective EVAR or fenestrated EVAR (F-EVAR) for asymptomatic AAA in a single tertiary hospital were retrospectively included. Three groups of patients were defined: patients with a patent IMA who underwent embolization during EVAR/F-EVAR (group 1), those with a patent IMA who did not undergo embolization during EVAR/F-EVAR (group 2), and those with a chronically occluded IMA (group 3). Preoperative aortic morphology, demographics, and procedural details were recorded. Aneurysmal growth (≥5 mm), reintervention, and overall mortality rates were analyzed using multivariate proportional hazard multivariate modeling. Propensity scores were constructed, and inverse probability weighting was applied to a new set of multivariate analyses to perform a sensitivity analysis.

RESULTS

A total of 266 patients (male, 95% [n = 249]) with a median age of 70 (65-77) years were included, with F-EVAR procedures comprising 87 (32.7%) of the interventions. There were 52, 142, and 72 patients in groups 1, 2, and 3, respectively. Changes in aneurysmal sac size did not differ between groups, nor did overall survival or reintervention rates at 24 months. IMA embolization was not identified as an independently protective factor for aneurysmal growth during follow-up (relative risk [RR] = 2.82/mm [0.96-8.28], P = .060), whereas accessory renal arteries (RR = 5.07/mm [1.72-14.96], P = .003) and a larger preoperative aneurysmal diameter (RR = 1.09/mm [1.03-1.15], P = .004) were independent risk factors for sac enlargement.

CONCLUSIONS

Preventive embolization of the IMA during EVAR or F-EVAR did not promote aneurysmal sac shrinking or decrease the reintervention rate at 2-year follow-up.

Clinical Comparison between Early and Late Spontaneous Sac Shrinkage after Endovascular Aortic Aneurysm Repair

BACKGROUND

Early spontaneous shrinkage (ESS) of abdominal aortic aneurysm (AAA) within 1 year after endovascular aortic aneurysm repair (EVAR) could be a predictor of durable success. However, late spontaneous shrinkage (LSS) during longer follow-up has not been well addressed. We compared late complications of ESS and LSS.

METHODS

Our series of elective EVAR for infrarenal AAA from June 2007 to December 2017 was reviewed. Patients with ≥1 year of follow-up with computed tomography (CT) studies were included. Patients with any reintervention within 1 year were excluded. Spontaneous shrinkage (SpS) was defined as a diameter reduction ≥10 mm without any reintervention. ESS was defined as SpS within 1 year, and LSS was defined as SpS occurring after 1 year of follow-up. Aneurysms that became larger than the original size after SpS were defined as re-expansion. Late complications (re-expansion, reintervention, and aneurysm-related death) and related factors were compared between ESS and LSS.

RESULTS

A total of 495 patients were enrolled. Median follow-up was 43 months [24-67, interquartile range (IQR)]. Among patients, 126 ESS and 55 LSS occurred. The cumulative rates of SpS were 25.7±2.0%, 37.4±2.4%, and 47.3±3.7% at 1, 3, and 7 years, respectively. There was 1 re-expansion and 6 reinterventions during further follow-up after SpS. The rates of freedom from late complications at 5 years were not significantly different between ESS (89.2±4.0%) and LSS (95.8±4.1%) (P = 0.465). Regression analysis revealed that the Zenith device was significantly related to ESS compared to the Excluder (P = 0.006) and Endurant (P = 0.040) . More than 6 preoperative patent lumbar arteries negatively correlated with ESS (P = 0.023). However, these factors had no significant impact on LSS.

CONCLUSIONS

The rates of late complications after SpS were comparable between ESS and LSS. Patients with delayed sac shrinkage with a reduction in diameter ≥10 mm should expect the same durable success as patients with quick shrinkage.

Recent Update of Endovascular Type 2 Endoleak Management

EVAR has been used clinically for almost three decades, and it has been widely applied in clinical practice and has been applied to difficult cases as devices and techniques have evolved. Although the major advantage of EVAR is its lower perioperative mortality, compared with open surgery, late-onset complications such as endoleaks have become major issues, requiring lifelong follow-up after EVAR. The clinical guidelines have been updated, and many systematic reviews/meta-analyses and multi-center registries have been published; surgeons must keep up-to-date regarding these changes. In this review, the author reviews evidence on the recent update of the type 2 endoleak management.