Influencing Factors for Abdominal Aortic Aneurysm Sac Shrinkage and Enlargement after EVAR: Clinical Reviews before Introduction of Preoperative Coil Embolization

Identifying Patients at High Risk for Post-EVAR Aneurysm Sac Growth

PURPOSE

Post-EVAR (endovascular aneurysm repair) aneurysm sac growth can be seen as therapy failure as it is a risk factor for post-EVAR aneurysm rupture. This study sought to identify preoperative patient predictors for developing post-EVAR aneurysm sac growth.

MATERIAL AND METHODS

A systematic review was conducted to select potential predictive preoperative factors for post-EVAR sac growth (including a total of 34.886 patients), which were evaluated by a retrospective single-center analysis of patients undergoing EVAR between 2009 and 2019 (N=247) with pre-EVAR computed tomography scans and at least 1 year follow-up. The primary study outcome was post-EVAR abdominal aortic aneurysm (AAA) sac enlargement (≥5 mm diameter increase). Multivariate Cox regression and Kaplan-Meier survival curves were constructed.

RESULTS

Potential correlative factors for post-EVAR sac growth included in the cohort analysis were age, sex, anticoagulants, antiplatelets, renal insufficiency, anemia, low thrombocyte count, pulmonary comorbidities, aneurysm diameter, neck diameter, neck angle, neck length, configuration of intraluminal thrombus, common iliac artery diameter, the number of patent lumbar arteries, and a patent inferior mesenteric artery. Multivariate analysis showed that infrarenal neck angulation (hazard ratio, 1.014; confidence interval (CI), 1.001-1.026; p=0.034) and the number of patent lumbar arteries (hazard ratio, 1.340; CI, 1.131-1.588; p<0.001) were associated with post-EVAR growth. Difference in estimated freedom from post-EVAR sac growth for patients with ≥4 patent lumbar arteries versus <4 patent lumbar arteries became clear after 2 years: 88.5% versus 100%, respectively (p<0.001). Of note, 31% of the patients (n=51) with ≥4 patent lumbar arteries (n=167) developed post-EVAR sac growth. In our cohort, the median maximum AAA diameter was 57 mm (interquartile range [IQR] = 54-62) and the median postoperative follow-up time was 54 months (IQR = 34-79). In all, 23% (n=57) of the patients suffered from post-EVAR growth. The median time for post-EVAR growth was 37 months (IQR = 24-63). In 46 of the 57 post-EVAR growth cases (81%), an endoleak was observed; 2.4% (n=6) of the patients suffered from post-EVAR rupture. The total mortality in the cohort was 24% (n=60); 4% (n=10) was AAA related.

CONCLUSIONS

This study showed that having 4 or more patent lumbar arteries is an important predictive factor for postoperative sac growth in patients undergoing EVAR.

CLINICAL IMPACT

This study strongly suggests that having 4 or more patent lumbar arteries should be included in preoperative counseling for EVAR, in conjunction to the instructions for use (IFU).

Endovascular Treatment of Abdominal Aortic Aneurysm: Impact of Diabetes on Endoleaks and Reintervention

Background: Diabetes has a protective effect on abdominal aortic aneurysms (AAAs); however, there are contrasting reports on the impact of diabetes on endovascular aortic repair (EVAR) outcomes, endoleaks (ELs) being the major negative outcome. The present study characterizes ELs and their outcomes in AAA patients, diabetic or not. Methods: This single-center, retrospective, comparative study was carried out on 324 AAA patients who underwent elective EVARs between 2007 and 2016 at the University Hospital of Liège (Belgium). The primary endpoint was the incidence and effect of ELs on the evolution of the aneurysmal sac; the secondary endpoints were surgical reintervention and mortality rate. Diabetic and non-diabetic patients were compared with respect to various risk factors by logistic regression, while a Cox regression was used to analyze survival. Results: In AAA patients meeting the inclusion criteria (n = 248), 23% were diabetic. EL incidence was comparable (p = 0.74) in diabetic (38.7%) vs. non-diabetic (43.9%) patients. EL risk factors were age (HR = 1.04, p = 0.014) and fibrate intake (HR = 3.12, p = 0.043). A significant association was observed between ELs and aneurysm sac enlargement (p < 0.001), regardless of group (p = 0.46). Aneurysm sac regression per month for non-diabetic patients was -0.24 ± 0.013, while for diabetics it was -0.18 ± 0.027 (p = 0.059). Dyslipidemia (HR = 3.01, p = 0.0060) and sulfonylureas (HR = 8.43, p = 0.043) were associated with shorter EL duration, while diabetes (HR = 0.080, p = 0.038) and beta blockers (HR = 0.46, p = 0.036) were associated with longer EL duration. The likelihood of reoperation decreased with more recent surgery (OR = 0.90, p = 0.040), regardless of diabetic status. All-cause mortality was higher for the non-diabetic group (45.5% vs. 26.3%, p = 0.0096). Conclusions: Endoleak occurrence is a known risk factor for sac expansion. In diabetic patients, endoleaks lasted longer, and regression of the aneurysm sac tended to be slower. The number and type of reintervention was not related to the diabetic status of AAA patients, but overall survival was higher in patients with diabetes.

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.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

Stability of the aneurysmatic sac post-EVAR could no longer be a reliable criterion of healing

BACKGROUND

Evaluation of the impact of aneurysm sac behavior in terms of either stability or shrinkage after endovascular aneurysm repair (EVAR) on long-term clinical outcomes.

METHODS

A retrospective study was conducted on 1483 consecutive patients who underwent EVAR from 1999 to 2021 at our institution. 1037 patients met inclusion criteria (1037/1483, 69.9%): abdominal aortic or aorto-iliac aneurysm, elective surgery, follow-up (FU) ≥12 months. Patients who had sac stability (330/1037, 31.8%) and patients who demonstrated sac shrinkage (542/1037, 52.2%) at FU were compared; patients who presented sac increase at FU were excluded (165/1037, 16%).

PRIMARY ENDPOINTS

rupture rates, need for surgical conversion, and long-term aneurysm-related mortality. Secondary endpoints: all type endoleak rates and long-term reintervention rates.

RESULTS

Mean FU was 61.2 months (IQ 26-85.7 months). In terms of comorbidities, the group of patients with stable sac showed greater association with polidistrectual atherosclerotic manifestations. Estimated 12-year survival was 42.9% in the stable sac group and 65% in the shrinked group (P<0.001), although there were no significant differences in terms of freedom from aneurysm-related death (97.3% vs. 95.4% estimated at 12 years, P=0.493). Patients with sac stability had higher rates of rupture (2.1% vs. 0.6%, P=0.035) and surgical conversion (2.1% vs. 0.6%, P=0.035). The stable sac group had significantly higher rates of all type endoleak during FU (45.8% vs. 24%, P<0.001). Estimated 12-year freedom from reintervention rates were 56.2% and 83.9% respectively (P<0.001).

CONCLUSIONS

After more than 20 years of EVAR experience it is probably time to reconsider the procedure clinical success parameters as a patient with a stable sac cannot be considered healed.

A stable aneurysm sac after endovascular aneurysm repair as a predictor for mortality, an in-depth analysis

OBJECTIVES

The aim of this study was to compare the long-term survival in patients with a stable aneurysmal sac and those with aneurysmal sac regression after endovascular aneurysm repair (EVAR) and to identify independent risk factors for aneurysmal sac regression and mortality after EVAR.

METHODS

We reviewed all patients who underwent EVAR between 2005 and 2018 with a computed tomography angiography available at 1-year follow-up. Aneurysm sac regression was defined as a diameter decrease of more than 10%. We used a multivariable regression to identify independent risk factors for sac regression. Kaplan-Meier analysis and Cox regression were done to test differences in 5-year mortality between a stable sac and sac regression.

RESULTS

The inclusion criteria were met by 325 patients, 185 in the sac regression group and 140 in the stable sac group. Multivariable logistic regression analysis showed that treatment for a ruptured aneurysm was an independent risk factor for aneurysmal sac regression (hazard ratio [HR], 0.26; 95% confidence interval [CI], 0.07-0.96). Age (HR, 1.05; 95% CI, 1.01-1.09), ischemic heart disease (HR, 1.94; 95% CI, 1.13-3.31), neck thrombus (HR, 2.72; 95% CI, 1.07-6.95), and a type II endoleak (HR, 19.21; 95% CI, 7.32-50.40) were independent risk factors for a stable aneurysm sac diameter. Multivariable Cox regression showed a significantly increased risk of mortality for patients with a stable aneurysm sac after EVAR (odds ratio, 2.25; 95% CI, 1.36-3.72). There was no significant difference in cause of death between the two groups.

CONCLUSION

A stable aneurysm sac after EVAR is associated with increased mortality. Age, ischemic heart disease, neck thrombus, and a type II endoleak are independent risk factors for a stable sac. However, a well-founded explanation for this finding is still lacking. Future research should be focussed on aggressive treatment of type II endoleaks and inflammatory processes as potential pathophysiological mechanisms.

Importance of Follow-up Imaging in the Detection of Delayed Type 2 Endoleaks Despite Complete Aneurysmal Sac Shrinkage

Type 2 endoleaks usually constitute a benign and self-limited phenomenon, which rarely leads to aneurysmal sac expansion. However, in a small subset of patients, a persistent type 2 endoleak might pressurise the aneurysmal sac causing expansion. The authors present two cases with delayed new-onset type 2 endoleak. One occurred after standard endovascular aortic repair and the other after chimney endovascular aortic repair, causing expansion of the aneurysmal sac after a period of complete aneurysmal sac shrinkage. Accordingly, there is a risk of sac re-expansion due to delayed onset endoleaks, independent of the technique, justifying the need for a continuous follow-up despite long-term aneurysmal sac shrinkage.

Pre-operative Aneurysm Thrombus Volume, But Not Density, Predicts Type 2 Endoleak Rate Following Endovascular Aneurysm Repair

BACKGROUND

The impact of aneurysm thrombus characteristics on type 2 endoleak rate following endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) is unclear. The purpose of this study is to determine the impact of pre-operative aneurysm thrombus volume and density on the incidence of type 2 endoleak following EVAR for infrarenal AAA.

METHODS

A retrospective analysis was completed on all patients who underwent standard EVAR at an academic medical institution between May 1, 2010 and June 1, 2016 with a minimum follow-up period of 12 months. The final analysis included 170 patients. Thrombus volume and density were determined by analyzing pre-operative computed tomography angiography (CTA) scans using the TeraRecon plaque analysis module. The number and diameter of patent infrarenal aortic branch vessels were also identified. Type 2 endoleak was diagnosed by post-operative CTA, duplex ultrasound, or angiography.

RESULTS

Over a median follow-up period of 29 months, 88 (51.8%) of 170 patients had a type 2 endoleak. The thrombus volume as a proportion of the infrarenal aorta volume was significantly lower in patients with type 2 endoleak (odds ratio [OR] 0.034, 95% confidence interval [CI] 0.005-0.291, P = 0.002). The number of patent lumbar arteries was significantly greater in patients with type 2 endoleak (OR 1.45, 95% CI 1.16-1.56, P < 0.0005). Both variables independently predicted the incidence of type 2 endoleak in a multivariate analysis. Thrombus density was not related to the incidence of type 2 endoleak.

CONCLUSIONS

A lower ratio of thrombus volume/infrarenal aorta volume and a higher number of patent lumbar arteries were associated with an increased incidence of type 2 endoleak. A multivariate logistic regression model was generated to pre-operatively predict the risk of type 2 endoleak. This model can guide the stratification of patients for intensity of endoleak surveillance following EVAR and consideration of pre-operative treatment.

Post-EVAR aneurysm sac shrinkage is prognostically favorable, but does not justify withholding follow-up

BACKGROUND

One of the main drawbacks of endovascular aortic aneurysm repair (EVAR) compared to open aortic surgery is the possibility of developing endoleaks and secondary aneurysm rupture, requiring frequent imaging follow-up. This study aims to identify prognostic factors that could be incorporated in follow-up protocols, which might lead to better personalized, lower cost and safe EVAR follow-up.

METHODS

A retrospective study was performed including all patients who underwent elective EVAR from January 2000 to December 2015. Follow-up data were gathered by reviewing medical files for radiographic imaging. Linear and logistic regressions were used to assess predictive factors for aneurysm shrinkage.

RESULTS

In 361 patients, aneurysm sac shrinkage of 10 mm or more was measured in 152 (42.1%) patients. Patients with ≥10-mm aneurysm shrinkage had fewer endoleaks (4.3% vs. 24.6%, P<0.0001) and fewer re-interventions for endoleak (3.0% vs. 10.1%, P=0.007). Aneurysm sac shrinkage was correlated with the absence of endoleak development (OR 0.36, 95% CI 0.19-0.66, P=0.001). In patients who had achieved ≥10-mm shrinkage of the aneurysm sac, no further significant growth was seen, compared to 38 (15.3%) patients who did not attain size reduction (P<0.001).

CONCLUSIONS

Once patients achieve ≥10-mm aneurysm sac shrinkage, they are less prone to developing subsequent aneurysm growth and have significantly lower risk of requiring surgery for endoleaks. However, a small number of patients remain at risk of requiring endoleak surgery after aneurysm shrinkage. Therefore, we would not recommend ceasing life-long imaging follow-up after significant aneurysm sac shrinkage, though it might be safe to increase the interval of follow-up.

Perioperative factors associated with aneurysm sac size changes after endovascular aneurysm repair

PURPOSE

To identify the perioperative factors associated with aneurysm size changes after endovascular aortic aneurysm repair (EVAR).

METHODS

Between August, 2008 and December, 2014, 187 patients underwent EVAR treatment in our institution. The subjects of this study were 135 of these patients without peripheral artery disease, who were followed up with computed tomography (CT) for 3 years. Significant aneurysm size change was defined as sac size change of more than 5 mm from the baseline.

RESULTS

Sac enlargement was identified in 25 patients (18.5%) and sac shrinkage was identified in 59 (43.7%) patients. The factors associated with sac enlargement were postoperative pulse wave velocity (OR: odds ratio 3.80, p = 0.047), prevalence of a type 2 endoleak 1 week after surgery (OR 4.26, p = 0.022), inner diameter (OR 1.10, p = 0.005), and distance from the lower renal artery to the terminal aorta (OR 1.05, p = 0.017). The factors associated with sac shrinkage were prevalence of a type 2 endoleak (OR 0.09, p < 0.001) and preoperative pulse wave velocity (OR 0.32, p = 0.022). The factors independently associated with type 2 endoleak were the use of an Excluder device (OR 3.99, p = 0.002) and the length of the aneurysm (OR 1.02, p = 0.027).

CONCLUSION

Inner diameter, treatment length, perioperative pulse wave velocity, and type 2 endoleak were associated with sac size changes after EVAR.

The Influence of Preoperative Aneurysmal Thrombus Quantity and Distribution on the Development of Type II Endoleaks with Aneurysm Sac Enlargement After EVAR of AAA

PURPOSE

To determine the influence of preoperative aneurysmal thrombus quantity and distribution on the development of type II endoleak with aneurysm sac enlargement after endovascular aneurysm repair (EVAR).

MATERIALS AND METHODS

We retrospectively analyzed the pre- and postoperatively performed CT scans of 118 patients who had follow-up imaging for at least 1 year after EVAR available. We assessed preoperative thrombus perimeter (T Peri), diameter (T Dia), cross-sectional area (T CSA), and volume (T Vol). The preoperative thrombus distribution was classified into no thrombus, semilunar-shaped (anterior, right side, left side, posterior) thrombus, and circumferential type thrombus. The number of preoperative patent aortic side branches (ASB) was identified. Endpoint was type II endoleak with aneurysm volume (A Vol) increase of ≥5 % during follow-up.

RESULTS

During follow-up (2 years, range 1-9 years), 17 patients with type II endoleak had significant A Vol increase. Less preoperative T Peri, T Dia, T CSA, and T Vol were associated with A Vol increase. A circumferential thrombus distribution significantly protected against aneurysm enlargement (p = 0.028). The variables with the strongest significance for A Vol increase were preoperative T Vol/A Vol ratio (OR 0.95; p = 0.037) and number of patent ASB (OR 3.52; p < 0.001).

CONCLUSION

A low preoperative T Vol/A Vol ratio and a high number of patent ASB were associated with aneurysm sac enlargement after EVAR.

Impact of Age and Intraluminal Thrombus Volume on Abdominal Aortic Aneurysm Sac Enlargement after Endovascular Repair

BACKGROUND

Abdominal aneurysmal sac enlargement after endovascular aortic repair (EVAR) is a critical issue. However, the predictors have not yet been fully determined. Although unrecognized, intraluminal thrombus volume (ITV) is an important index. Therefore, we retrospectively evaluated the correlation among preoperative ITV, residual type II endoleak, and sac enlargement after EVAR, based on the long-term follow-up.

METHODS

Between 2006 and 2011, 151 consecutive patients underwent EVAR at a single cardiovascular institute. Emergency surgery was performed on 7 patients (4.7%). Of 148 patients excluding 3 patients with residual type I endoleak, sac enlargement (≥5 mm progression) after EVAR was observed in 24 patients (16.2%) and 8 patients required reintervention. The mean follow-up period was 2.4 ± 1.4 years. The outer volume and enhanced luminal volume were calculated from enhanced 1-mm slice computed tomography, and the difference was defined as ITV.

RESULTS

Age (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.04-1.20, P = 0.0007), outer volume (HR 1.04, 95% CI 1.01-1.07, P = 0.0118), percentage of ITV (HR 0.90, 95% CI 0.84-0.96, P = .0027), and type II endoleak (HR 10.15, 95% CI 3.55-31.10, P < 0.0001) were isolated as predictors of sac enlargement by multivariate analysis. Also, patent inferior mesenteric artery (odds ratio [OR] 4.45, 95% CI 1.38-20.07, P = 0.0105) and percentage of ITV < 30.1% (OR 3.52, 95% CI 1.32-10.30, P = 0.0112) were detected as independent risk factors for residual type II endoleaks. Additionally, in patients without endoleak, patient age (≥83 years) was an independent risk factor for sac enlargement after EVAR (P = 0.0056).

CONCLUSION

Age and ITV percentage had significantly great impact on sac enlargement and type II endoleak after EVAR.