Long-term outcomes of immediate repair compared with surveillance of small abdominal aortic aneurysms

Peak wall rupture index is associated with risk of rupture of abdominal aortic aneurysms, independent of size and sex

BACKGROUND

Information on the predictive determinants of abdominal aortic aneurysm rupture from CT angiography are scarce. The aim of this study was to investigate biomechanical parameters in abdominal aortic aneurysms and their association with risk of subsequent rupture.

METHODS

In this retrospective study, the digital radiological archive was searched for 363 patients with ruptured abdominal aortic aneurysms. All patients who underwent at least one CT angiography examination before aneurysm rupture were included. CT angiography results were analysed to determine maximum aneurysm diameter, aneurysm volume, and biomechanical parameters (peak wall stress and peak wall rupture index). In the primary survival analysis, patients with abdominal aortic aneurysms less than 70 mm were considered. Sensitivity analyses including control patients and abdominal aortic aneurysms of all sizes were performed.

RESULTS

A total of 67 patients who underwent 109 CT angiography examinations before aneurysm rupture were identified. The majority were men (47, 70%) and the median age at the time of CTA examination was 77 (71-83) years. The median maximum aneurysm diameter was 56 (interquartile range 46-65) mm and the median time to rupture was 2.13 (interquartile range 0.64-4.72) years. In univariable analysis, maximum aneurysm diameter, aneurysm volume, peak wall stress, and peak wall rupture index were all associated with risk of rupture. Women had an increased HR for rupture when adjusted for maximum aneurysm diameter or aneurysm volume (HR 2.16, 95% c.i. 1.23 to 3.78 (P = 0.007) and HR 1.92, 95% c.i. 1.06 to 3.50 (P = 0.033) respectively). In multivariable analysis, the peak wall rupture index was associated with risk of rupture. The HR for peak wall rupture index was 1.05 (95% c.i. 1.03 to 1.08) per % (P < 0.001) when adjusted for maximum aneurysm diameter and 1.05 (95% c.i. 1.02 to 1.08) per % (P < 0.001) when adjusted for aneurysm volume.

CONCLUSION

Biomechanical factors appear to be important in the prediction of abdominal aortic aneurysm rupture. Women are at increased risk of rupture when adjustments are made for maximum aneurysm diameter alone.

Machine learning-based prediction of abdominal aortic aneurysms for individualized patient care

OBJECTIVE

The United States Preventative Services Task Force guidelines for screening for abdominal aortic aneurysms (AAA) are broad and exclude many at risk groups. We analyzed a large AAA screening database to examine the utility of a novel machine learning (ML) model for predicting individual risk of AAA.

METHODS

We created a ML model to predict the presence of AAAs (>3 cm) from the database of a national nonprofit screening organization (AAAneurysm Outreach). Participants self-reported demographics and comorbidities. The model is a two-layered feed-forward shallow network. The ML model then generated AAA probability based on patient characteristics. We evaluated graphs to determine significant factors, and then compared those graphs with a traditional logistic regression model.

RESULTS

We analyzed a cohort of 10,033 patients with an AAA prevalence of 2.74%. Consistent with logistic regression analysis, the ML model identified the following predictors of AAA: Caucasian race, male gender, advancing age, and recent or past smoker with recent smoker having a more profound affect (P < .05). Interestingly, the ML model showed body mass index (BMI) was associated with likelihood of AAAs, especially for younger females. The ML model also identified a higher than predicted risk of AAA in several groups, including female nonsmokers with cardiac disease, female diabetics, those with a family history of AAA, and those with hypertension or hyperlipidemia at older ages. An elevated BMI conveyed a higher than expected risk in male smokers and all females. The ML model also identified a complex relationship of both diabetes mellitus and hyperlipidemia with gender. Family history of AAA was a more important risk factor in the ML model for both men and women too.

CONCLUSIONS

We successfully developed an ML model based on an AAA screening database that unveils a complex relationship between AAA prevalence and many risk factors, including BMI. The model also highlights the need to expand AAA screening efforts in women. Using ML models in the clinical setting has the potential to deliver precise, individualized screening recommendations.

A dedicated risk prediction model of 1-year mortality following endovascular aortic aneurysm repair involving the renal-mesenteric arteries

OBJECTIVE

Treatment goals of prophylactic endovascular aortic repair of complex aneurysms involving the renal-mesenteric arteries (complex endovascular aortic repair [cEVAR]) include achieving both technical success and long-term survival benefit. Mortality within the first year after cEVAR likely indicates treatment failure owing to associated costs and procedural complexity. Notably, no validated clinical decision aid tools exist that reliably predict mortality after cEVAR. The purpose of this study was to derive and validate a preoperative prediction model of 1-year mortality after elective cEVAR.

METHODS

All elective cEVARs including fenestrated, branched, and/or chimney procedures for aortic disease extent confined proximally to Ishimaru landing zones 6 to 9 in the Society for Vascular Surgery Vascular Quality Initiative were identified (January 2012 to August 2023). Patients (n = 4053) were randomly divided into training (n = 3039) and validation (n = 1014) datasets. A logistic regression model for 1-year mortality was created and internally validated by bootstrapping the AUC and calibration intercept and slope, and by using the model to predict 1-year mortality in the validation dataset. Independent predictors were assigned an integer score, based on model beta-coefficients, to generate a simplified scoring system to categorize patient risk.

RESULTS

The overall crude 1-year mortality rate after elective cEVAR was 11.3% (n = 456/4053). Independent preoperative predictors of 1-year mortality included chronic obstructive pulmonary disease, chronic renal insufficiency (creatinine >1.8 mg/dL or dialysis dependence), hemoglobin <12 g/dL, decreasing body mass index, congestive heart failure, increasing age, American Society of Anesthesiologists class ≥IV, current tobacco use, history of peripheral vascular intervention, and increasing extent of aortic disease. The 1-year mortality rate varied from 4% among the 23% of patients classified as low risk to 23% for the 24% classified as high risk. Performance of the model in validation was comparable with performance in the training data. The internally validated scoring system classified patients roughly into quartiles of risk (low, low/medium, medium/high and high), with 52% of patients categorized as medium/high to high risk, which had corresponding 1-year mortality rates of 11% and 23%, respectively. Aneurysm diameter was below Society for Vascular Surgery recommended treatment thresholds (<5.0 cm in females, <5.5 cm in males) in 17% of patients (n = 679/3961), 41% of whom were categorized as medium/high or high risk. This subgroup had significantly increased in-hospital complication rates (18% vs 12%; P = .02) and 1-year mortality (13% vs 5%; P < .0001) compared with patients in the low- or low/medium-risk groups with guideline-compliant aneurysm diameters (≥5.0 cm in females, ≥5.5 cm in males).

CONCLUSIONS

This validated preoperative prediction model for 1-year mortality after cEVAR incorporates physiological, functional, and anatomical variables. This novel and simplified scoring system can effectively discriminate mortality risk and, when applied prospectively, may facilitate improved preoperative decision-making, complex aneurysm care delivery, and resource allocation.

Increased Mortality in Octogenarians Undergoing Endovascular Aortic Aneurysm Repair for Smaller Aneurysms Warrants Caution

BACKGROUND

Geriatric patients constitute a growing portion of the general population, with particular increase in the prevalence of octogenarians. The incidence and prevalence of abdominal aortic aneurysms (AAAs) have been clearly shown to be associated with advancing age. The effect of advanced age in outcomes from endovascular aneurysm repair (EVAR) is unclear. We study the effect of advanced age, as an independent risk factor for mortality in octogenarian geriatric patients (OGPs) compared to nonoctogenarian geriatric patients (NOGPs) undergoing EVAR.

METHODS

The 2011-2017 American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) Procedure-Targeted Vascular database was queried for geriatric patients (>65 years) undergoing EVAR for symptomatic and asymptomatic indications. A multivariable logistic regression analysis was performed comparing outcomes between OGPs and NOGPs.

RESULTS

Of the 10,490 geriatric patients who underwent EVAR, 7,508 (71.6%) were NOGPs and 2,982 (28.4%) were OGPs. Octogenarians were more often female (82.3% vs. 76.7%). In comparison to NOGPs, fewer OGPs were treated for AAA <5.5 cm (46.7% vs. 54.9%, P < 0.001) and AAA <5.0 cm (19.2% vs. 24.0%, P < 0.001). Nearly 90% of male and over 80% of female NOGPs and OGPs treated for AAA <5.0 cm were asymptomatic. Octogenarian geriatric patients (OGPs) had less dyspnea (15.3% vs. 17.3%, P = 0.01), chronic obstructive pulmonary disease (16.1% vs. 20.5%, P < 0.001), diabetes (12.7% vs. 17.8%, P < 0.001), and smoking (13.2% vs. 36.3%, P < 0.001) compared to NOGPs. Octogenarian geriatric patients (OGPs) were found to have a greater length of stay (2 days vs. 1 day, P < 0.001), as well as rate of mortality (3.4% vs. 1.7%, P < 0.001). Both symptomatic and asymptomatic OGPs had a higher rate of mortality than their NOGP counterparts (symptomatic 16% vs. 9.5%, P < 0.001; asymptomatic 1.3% vs. 0.5%, P < 0.001). Multivariate logistic regression analysis showed OGPs to have increased overall associated risk of mortality compared to NOGPs (odds ratio (OR) 1.88, confidence interval (CI) 1.39-2.54, P < 0.001), as well as in the symptomatic (OR 1.54, CI 1.06-2.23, P < 0.001) and asymptomatic cohorts (OR 2.66, CI 1.59-4.45, P < 0.001).

CONCLUSIONS

Octogenarian geriatric patients (OGPs) accounted for over a quarter of geriatric patients undergoing EVAR. This elderly group was associated with an increased rate and risk of mortality compared to NOGPs, even when controlling for known risk factors for mortality. Given this increased risk of mortality in OGPs undergoing EVAR, elective treatment of AAAs in this advanced age group should be performed with caution, particularly in those with diameters in which the risk of rupture may not warrant repair.

Long-Term Outcomes of Simple Endovascular Aneurysm Repair Based on the Initial Aortic Diameter

PURPOSE

We aimed to investigate the effects of initial abdominal aortic aneurysm (AAA) diameter on aneurysmal sac expansion/shrinkage, endoleaks, and reintervention postelective simple endovascular aneurysm repair (EVAR).

METHODS

Overall, 228 patients monitored for >1 year after EVAR were analyzed. Male and female participants with initial AAA diameters <55 mm and <50 mm, respectively, composed the small group (group S), while those with initial AAA diameters ≥55 mm (men) and ≥50 mm (women) composed the large group (group L). Aneurysmal sac expansion of 10 mm and/or reintervention during follow-up (composite event) and its related factors were evaluated.

RESULTS

The 5-year freedom from composite event rate was significantly higher in group S (92.4 ± 2.8%) than that in group L (79.1 ± 4.9%; P <0.01). Multivariate analysis revealed AAA diameters before EVAR in group S (hazard ratio, 0.38; 95% confidence interval, 0.18-0.81; P = 0.01) and type II endoleak (T2EL) at discharge (hazard ratio, 2.83; 95% confidence interval, 1.29-6.20; P <0.01) as factors associated with the composite event. The freedom from composite event rate decreased to 51 ± 13% at 5 years in group L with T2EL.

CONCLUSIONS

Group S had high freedom from composite event rate; in group L, the rate decreased to 51% at 5 years with T2EL at discharge.

Clinical presentation, outcomes, and threshold for repair by sex in degenerative saccular vs fusiform aneurysms in the descending thoracic aorta

OBJECTIVE

Saccular-shaped thoracic aortic aneurysms (TAAs) are often treated at smaller diameters compared with fusiform TAAs, despite a lack of strong clinical evidence to support this practice. The aim of this study was to examine differences in presentation, treatment, and outcomes between saccular TAAs and fusiform TAAs in the descending thoracic aorta. We also examined the need for sex-specific treatment thresholds for TAAs.

METHODS

All Vascular Quality Initiative (VQI) patients undergoing thoracic endovascular aneurysm repair (TEVAR) for degenerative TAAs in the descending thoracic aorta from 2012 through 2022 were reviewed. Patients were stratified by urgency: emergent/urgent vs elective repairs (ruptured/symptomatic). Demographics, comorbidities, anatomical/procedural characteristics, and outcomes for fusiform TAAs and saccular TAAs were compared. Cumulative distribution curves were used to plot the proportion of patients who underwent emergent/urgent repair according to sex-stratified aortic diameter.

RESULTS

Among 655 emergent/urgent TEVARs, 37% were performed for saccular TAAs, whereas among 1352 elective TEVARs, 35% had saccular TAA morphology. Compared with fusiform TAAs, saccular TAAs more frequently underwent emergent/urgent (ruptured/symptomatic) TEVAR below the repair threshold in both females (<50 mm: 38% vs 10%; relative risk, 3.39; 95% confidence interval [CI], 2.04-5.70; P < .001), and males (<55 mm: 47% vs 21%; relative risk, 2.26; 95% CI, 1.60-3.18; P < .001). Moreover, among patients with emergent/urgent fusiform TAAs, females presented at smaller diameters compared with males, whereas there was no difference in preoperative aneurysm diameter among patients with saccular TAAs. Regarding outcomes, emergent/urgent treated saccular TAAs had similar postoperative outcomes and 5-year mortality compared with fusiform TAAs. Nevertheless, in the elective cohort, patients with saccular TAAs had similar postoperative mortality compared with those with fusiform TAAs, but a lower rate of postoperative spinal cord ischemia (0.7% vs 3.2%; P = .010). Furthermore, patients with saccular TAAs had a higher rate of 5-year mortality compared with their fusiform counterparts (23% vs 17%; hazard ratio, 1.53; 95% CI, 1.12-2.10; P = .010).

CONCLUSIONS

Patients with saccular TAAs underwent emergent/urgent TEVAR at smaller diameters than those with fusiform TAAs, supporting current clinical practice guideline recommendations that saccular TAAs warrant treatment at smaller diameters. Furthermore, these data support a sex-specific treatment threshold for patients with fusiform TAAs, but not for those with saccular TAAs. Although there were no differences in outcomes following TEVAR between morphologies in the emergent/urgent cohort, patients with saccular TAAs who were treated electively were associated with higher 5-year mortality compared with those with fusiform TAAs.

The Comparison of Endovascular and Open Surgical Treatment for Ruptured Abdominal Aortic Aneurysm in Terms of Safety and Efficacy on the Basis of a Single-Center 30-Year Experience

OBJECTIVE

Ruptured abdominal aortic aneurysm (rAAA) is a critical condition with a high mortality rate. Over the years, endovascular aortic repair (EVAR) has evolved as a viable treatment option in addition to open repair (OR). The primary objective of this study was to compare the safety and efficacy of EVAR and OR for the treatment of rAAA based on a comprehensive analysis of our single-centre 30-year experience.

METHODS

Patients treated for rAAA at the Department of Vascular and Endovascular Surgery, University Hospital Düsseldorf, Germany from 1 January 1993 to 31 December 2022 were included. Relevant information was retrieved from archived medical records. Patient survival and surgery-related complications were analysed.

RESULTS

None of the patient-specific markers, emergency department-associated parameters, and co-morbidities were associated with patient survival. The 30-day and in-hospital mortality was higher in the OR group vs. in the EVAR group (50% vs. 8.7% and 57.1% vs. 13%, respectively). OR was associated with more frequent occurrence of more severe complications when compared to EVAR. Overall patient survival was 56 ± 5% at 12 months post-surgery (52 ± 6% for OR vs. 73 ± 11% for EVAR, respectively) (p < 0.05). Patients ≥70 years of age showed poorer survival in the OR group, with a 12-month survival of 42 ± 7% vs. 70 ± 10% for patients <70 years of age (p < 0.05). In the EVAR group, this age-related survival advantage was not found (12-month survival: ≥70 years: 67 ± 14%, <70 years: 86 ± 13%). Gender-specific survival was similar regardless of the applied method of care.

CONCLUSION

OR was associated with more severe complications in our study. EVAR initially outperformed OR for rAAA regarding patient survival while re-interventions following EVAR negatively affect survival in the long-term. Elderly patients should be treated with EVAR. Gender does not seem to have a significant impact on survival.

Role of Common Antihypertensives in the Growth of Abdominal Aortic Aneurysm at the Presurgical Stage

Background: Whether drug therapy slows the growth of abdominal aortic aneurysms (AAAs) in the Japanese population remains unknown. Methods and Results: In a multicenter prospective open-label study, patients with AAA at the presurgical stage (mean [±SD] AAA diameter 3.27±0.58 cm) were randomly assigned to treatment with candesartan (CAN; n=67) or amlodipine (AML; n=64) considering confounding factors (statin use, smoking, age, sex, renal function), with effects of blood pressure control minimized setting a target control level. The primary endpoint was percentage change in AAA diameter over 24 months. Secondary endpoints were changes in circulating biomarkers (high-sensitivity C-reactive protein [hs-CRP], malondialdehyde-low-density lipoprotein, tissue-specific inhibitor of metalloproteinase-1, matrix metalloproteinase [MMP] 2, MMP9, transforming growth factor-β1, plasma renin activity [PRA], angiotensin II, aldosterone). At 24 months, percentage changes in AAA diameter were comparable between the CAN and AML groups (8.4% [95% CI 6.23-10.59%] and 6.5% [95% CI 3.65-9.43%], respectively; P=0.23]. In subanalyses, AML attenuated AAA growth in patients with comorbid chronic kidney disease (CKD; P=0.04) or systolic blood pressure (SBP) <130 mmHg (P=0.003). AML exhibited a definite trend for slowing AAA growth exclusively in never-smokers (P=0.06). Among circulating surrogate candidates for AAA growth, PRA (P=0.02) and hs-CRP (P=0.001) were lower in the AML group. Conclusions: AML may prevent AAA growth in patients with CKD or lower SBP, associated with a decline in PRA and circulating hs-CRP.

2022 ACC/AHA guideline for the diagnosis and management of aortic disease: A report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate.

STRUCTURE

Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

Precocious Rupture of Abdominal Aortic Aneurysms Below Size Criteria for Repair: Risk Factors and Outcomes

BACKGROUND

Practice guidelines recommend elective repair for abdominal aortic aneurysms (AAAs) ≥ 5.5 cm in men and ≥ 5 cm in women to prevent rupture; however, some rupture at smaller diameters. We identify risk factors for rupture AAA (rAAA) below this threshold and compare outcomes following rAAA repair above/below size criteria.

METHODS

The Vascular Quality Initiative (2013-2019) was queried for patients undergoing repair for rAAA and stratified based on diameter into small and large cohorts [Small: < 5.5 cm (men), < 5.0 cm (women)]. Univariate analysis was performed, and Kaplan-Meier analysis compared overall survival, aneurysm-related mortality, and reintervention at 12 months.

RESULTS

Five thousand one hundred sixty two rAAA were identified. Small rAAA patients [n = 588] were more likely to have hypertension (81.3% vs. 77.0%, P < 0.02), diabetes (18.2% vs. 14.9%, P < 0.04), and end-stage renal disease (2.9% vs. 0.9%, P < 0.01) and be on optimal medical therapy (32.1% vs. 26.8%, P < 0.01). Women were more likely to rupture at smaller diameters compared to men (P < 0.01). Small rAAA patients were more likely to undergo endovascular aortic repair (EVAR) (70.2% vs. 56.0%, P < 0.01) and had lower in-hospital mortality (17.7% vs. 27.7%, P < 0.01) and fewer perioperative complications across all categories. At 12 months, small rAAA patients had better overall survival, freedom from aneurysm-related mortality, and freedom from reintervention, largely driven by EVAR approach.

CONCLUSIONS

More than 11% of patients presenting with ruptured AAA were below the recommended size threshold for repair, and they tended to be younger, non-White, and have hypertension, diabetes, and/or renal failure. Patients with small rAAA experienced lower in-hospital morbidity and mortality and improved 1-year survival, and EVAR was associated with better outcomes than open repair. However, women more frequently rupture at smaller diameters compared to men. Given contemporary elective outcomes for women, a randomized controlled trial for EVAR versus surveillance at a sex-specific size threshold is needed.

Brazilian Society for Angiology and Vascular Surgery guidelines on abdominal aortic aneurysm

The Brazilian Society of Angiology and Vascular Surgery, through the Guidelines Project, presents new Abdominal Aortic Aneurysm Guidelines, on the subject of care for abdominal aortic aneurysm patients. Its development prioritized descriptive guidelines, using the EMBASE, LILACS, and PubMed databases. References include randomized controlled trials, systematic reviews, meta-analyses, and cohort studies. Quality of evidence was evaluated by a pair of coordinators, aided by the RoB 2 Cochrane tool and the Newcastle Ottawa Scale forms. The subjects include juxtarenal aneurysms, infected aneurysms, and new therapeutic techniques, especially endovascular procedures. The current version of the guidelines include important recommendations for the primary topics involving diagnosis, treatment, and follow-up for abdominal aortic aneurysm patients, providing an objective guide for medical practice, based on scientific evidence and widely available throughout Brazil.

Glucagon-Like Peptide-1 Inhibits the Progression of Abdominal Aortic Aneurysm in Mice: The Earlier, the Better

OBJECTIVES

Glucagon-like peptide-1 (GLP-1) has a cardiovascular protective effect by preventing abdominal aortic aneurysm (AAA) formation. However, it is unclear at what point the agent should be administered to achieve the optimal effect. In this study, we aimed to determine whether administering the GLP-1 receptor agonist liraglutide during the earlier stages would more efficiently inhibit AAA progression in mice.

METHODS

Depending on the group, mice were given a daily dose of 300 μg/kg liraglutide for 28 days at 7, 14, and 28 days after aneurysm induction. The morphology of the abdominal aorta was monitored using 7.0 T magnetic resonance imaging (MRI) during the administration of liraglutide. After 28 days of administration, the AAA dilatation ratio was calculated, and histopathological examination was performed. Oxidative stress levels were evaluated by the expression of malondialdehyde (MDA) and matrix metalloproteinases (MMPs). The inflammatory response was also evaluated.

RESULTS

Liraglutide treatment led to a decrease in AAA formation, including a reduction in abdominal aorta expansion, elastin degradation in the elastic laminae, and vascular inflammation caused by leukocyte infiltration. The expression of MDA and the activity of MMPs (MMP-2, MMP-9) also decreased. Notably, administering liraglutide during the early stages resulted in a significant reduction in the dilatation rate of the aortic wall, as well as in MDA expression, leukocyte infiltration, and MMP activity in the vascular wall.

CONCLUSIONS

The GLP-1 receptor agonist liraglutide was found to inhibit AAA progression in mice by exerting anti-inflammatory and antioxidant effects, particularly during the early stages of AAA formation. Therefore, liraglutide may represent a potential pharmacological target for the treatment of AAA.

How does hemodynamics affect rupture tissue mechanics in abdominal aortic aneurysm: Focus on wall shear stress derived parameters, time-averaged wall shear stress, oscillatory shear index, endothelial cell activation potential, and relative residence time

An abdominal aortic aneurysm (AAA) is a critical health condition with a risk of rupture, where the diameter of the aorta enlarges more than 50% of its normal diameter. The incidence rate of AAA has increased worldwide. Currently, about three out of every 100,000 people have aortic diseases. The diameter and geometry of AAAs influence the hemodynamic forces exerted on the arterial wall. Therefore, a reliable assessment of hemodynamics is crucial for predicting the rupture risk. Wall shear stress (WSS) is an important metric to define the level of the frictional force on the AAA wall. Excessive levels of WSS deteriorate the remodeling mechanism of the arteries and lead to abnormal conditions. At this point, WSS-related hemodynamic parameters, such as time-averaged WSS (TAWSS), oscillatory shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) provide important information to evaluate the shear environment on the AAA wall in detail. Calculation of these parameters is not straightforward and requires a physical understanding of what they represent. In addition, computational fluid dynamics (CFD) solvers do not readily calculate these parameters when hemodynamics is simulated. This review aims to explain the WSS-derived parameters focusing on how these represent different characteristics of disturbed hemodynamics. A representative case is presented for spatial and temporal formulation that would be useful for interested researchers for practical calculations. Finally, recent hemodynamics investigations relating WSS-related parameters with AAA rupture risk assessment are presented. This review will be useful to understand the physical representation of WSS-related parameters in cardiovascular flows and how they can be calculated practically for AAA investigations.

2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate. Structure: Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate.

STRUCTURE

Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

High-density thrombus and maximum transverse diameter on multi-spiral computed tomography angiography combine to predict abdominal aortic aneurysm rupture

Objective

We attempted to measure maximum transverse diameter (MTD) of and CT values of ILT by using multi-spiral computed tomography angiography (MSCTA) to investigate the predictive value of MTD with different CT values of thrombus on the risk of AAA rupture.

Methods

Forty-five intact abdominal aortic aneurysms (IAAA) and 17 ruptured abdominal aortic aneurysms (RAAA) were included in this study. MTD and CT values in their planes were measured from MSCTA images and aneurysm lumen and thrombus volumes were calculated for the range of different CT values.

Results

The median of maximum CT value of thrombus at the plane of MTD was higher in RAAA (107.0 HU) than the median in IAAA (84.5 HU) (P < 0.001). Univariate logistic regression analysis showed that the maximum CT value was a risk factor for RAAA (P < 0.001). It was further found that the area under the ROC curve for thrombus maximum CT value in the MTD plane to predict RAAA was 0.848 (P < 0.001), with a cut-off value of 97.5 HU, a sensitivity of 82.35%, and a specificity of 84.44%. And the MTD of the abnormal lumen combined with the maximum CT value at its plane predicted RAAA with an area under the ROC curve of 0.901, a sensitivity of 76.47%, and a specificity of 97.78%. The further analysis of thrombus volume in the range of different CT value showed that median thrombus volume in RAAA in the range of 30 HU~150 HU was 124.2 cm³ which was higher than the median of 81.4 cm³ in IAAA (P = 0.005). To exclude confounding factors (aneurysm volume), we calculated the standardized thrombus (ILT volume/total aneurysm volume), and the thrombus volume in the range of 30 HU~150 HU in RAAA was positively correlated with the standardized thrombus volume (ρ = 0.885, P < 0.001), while the thrombus volume in the range of −100 HU~30 HU was not correlated with it (ρ = 0.309, P = 0.228).

Conclusions

High-density ILT shown on MSCTA in AAAs is associated with aneurysm rupture, and its maximum transverse diameter combined with the maximum CT value in its plane is a better predictor of RAAA.

Potential of Disease-Modifying Anti-Rheumatic Drugs to Limit Abdominal Aortic Aneurysm Growth

Inflammation is strongly implicated in the pathogenesis of abdominal aortic aneurysms (AAA). This review examined the potential role of biologic disease-modifying anti-rheumatic drugs (bDMARDs) as repurposed drugs for treating AAA. Published evidence from clinical and preclinical studies was examined. Findings from animal models suggested that a deficiency or inhibition of tumour necrosis factor-α (TNF-α) (standard mean difference (SMD): −8.37, 95% confidence interval (CI): −9.92, −6.82), interleukin (IL)-6 (SMD: −1.44, 95% CI: −2.85, −0.04) and IL-17 (SMD: −3.36, 95% CI: −4.21, −2.50) led to a significantly smaller AAA diameter compared to controls. Human AAA tissue samples had significantly increased TNF-α (SMD: 1.68, 95% CI: 0.87, 2.49), IL-1β (SMD: 1.93, 95% CI: 1.08, 2.79), IL-6 (SMD: 2.56, 95% CI: 1.79, 3.33) and IL-17 (SMD: 6.28, 95% CI: 3.57, 8.99) levels compared to non-AAA controls. In human serum, TNF-α (SMD: 1.11, 95% CI: 0.25, 1.97) and IL-6 (SMD: 1.42, 95% CI: 0.91, 1.92) levels were significantly elevated compared to non-AAA controls. These findings implicate TNF-α, IL-17 and IL-6 in AAA pathogenesis. Randomised controlled trials testing the value of bDMARDs in limiting AAA growth may be warranted.

Female Sex Is Associated With Reintervention and Mortality Following Elective Endovascular Abdominal Aortic Aneurysm Repair

OBJECTIVE

While sex differences in endovascular abdominal aortic aneurysm repair (EVAR) outcomes are increasingly reported, but contributing factors remain without consensus. We investigated disparities in sex-specific outcomes following elective EVAR at our institution and evaluated factors that may predispose females to increased morbidity and mortality.

METHODS

A retrospective chart review of all patients undergoing elective EVAR from 2011 to 2020 at a suburban tertiary care center was performed. The primary outcomes were five-year survival and freedom from reintervention. Fisher's exact test, t-tests, and Kaplan-Meier analysis using the rank-log test investigated associations between sex and outcomes. A multivariable Cox proportional hazard model controlling for age and common comorbidities evaluated the effect of sex on survival and freedom from reintervention.

RESULTS

Two hundred and seventy-three patients underwent elective EVAR during the study period, including 68 (25%) females and 205 (75%) males. Females were older on average than males (76 years vs. 73 years, p= <0.01) and were more likely to have chronic obstructive pulmonary disease (COPD; 38% versus 23%, p=0.01), require home oxygen therapy (9% versus 2%, p=0.04) or dialysis preoperatively (4% versus 0%, p=0.02). Distribution of other common vascular comorbidities was similar between the sexes. Thirty-day readmission was greater in females than males (18% versus 8%, p=0.02). Females had significantly lower survival at five years (48% ± 7.9% versus 65% ± 4.3%, p<0.01) and significantly lower one-year (89% ± 4.1% for females vs. 94% ± 1.7% for males, p=0.01) and five-year freedom from reintervention (69% ± 8.9% versus 84% ± 3.3%, p=0.02). On multivariable analysis, female sex (hazard ratio [HR]: 1.8, 95% confidence interval [CI]: 1.1-2.9), congestive heart failure (HR: 2.2, 95% CI: 1.2-3.9) and age (HR: 1.1, 95% CI: 1.0-1.1) were associated with 5-year mortality. Female sex remained as the only variable with a statistically significant association with five-year reintervention (HR: 2.4, 95% CI: 1.1-4.9).

CONCLUSIONS

Female sex was associated with decreased five-year survival and increased one and five-year reintervention following elective EVAR. Data from our institution suggests factors beyond patient age and baseline health risk likely contribute to greater surgical morbidity and mortality for females following elective EVAR.

Epicardial adipose tissue volume is associated with abdominal aortic aneurysm expansion

BACKGROUND

Epicardial adipose tissue volume (EATV) is associated with cardiovascular diseases such as coronary artery disease. However, no information is available regarding the relationship between EATV and abdominal aortic aneurysm (AAA) expansion. This study aimed to evaluate the association between EATV and the growth of AAA, and to identify predictors of AAA expansion.

METHODS

Between June 2009 and December 2019, a total of 906 patients underwent endovascular or open repair of AAA at our institution. Patients with previous cardiac surgery, previous ascending thoracic aortic surgery, ruptured AAA, infected AAA, inflammatory AAA, saccular aneurysm, solitary iliac aneurysm, or reintervention after treatment for AAA were excluded. Two hundred and thirty-seven patients with at least two preoperative computed tomography (CT) scans performed more than 180 days apart were included in this study. EATV within the pericardium was retrospectively quantified from preoperative non-contrast CT images using a 3D workstation. The EATV index was defined as EATV divided by body surface area. The AAA expansion rate was defined as the increase in AAA diameter per year, and patients were divided into the slow-expansion group, with an expansion rate < 5 mm/year, and the fast-expansion group, with an expansion rate ≥ 5 mm/year. The correlation between expansion rate and the EATV index was analyzed, and the cut-off value of the EATV index was determined using a receiver operating characteristics curve. Multivariate analysis was used to assess predictors of the AAA expansion rate.

RESULTS

The expansion rate of AAA was positively correlated with the EATV index (R = .237, P < .001). The initial aneurysm diameter (P < .001) and EATV index (P = .009) differed significantly between the two groups. The cut-off value of the EATV index was 60.3 cm³/m² (area under the curve, .658; 95% confidence interval [CI], .568-.749; sensitivity, 1.000; specificity, .309). Multivariate analysis revealed that the initial aneurysm diameter and an EATV index > 60.3 cm³/m² were significantly associated with the AAA expansion rate.

CONCLUSIONS

This study demonstrated that the EATV index was associated with AAA expansion.

Aortoiliac diameter and length in a healthy cohort

Objective

Diameter is currently the only screening and diagnostic criterion for asymptomatic aneurysms. Therefore, aortic and lower-extremity arterial diameter has diagnostic, therapeutic, and prognostic importance. We aimed to determine aortic and lower-extremity arterial reference diameters in a general population and compare them according to age, sex, and other characteristics.

Methods

We evaluated consecutive 3,692 patients who underwent computed tomography as part of a general health checkup from 2015–2019 in a single tertiary center. Aortic and lower-extremity arterial diameters and the most important factor related to arterial diameters were evaluated.

Results

The mean diameter of the abdominal aorta was 17.490 ± 2.110 mm, while that of the common iliac artery was 10.851 ± 1.689 mm. The mean diameter of the abdominal aorta was 18.377 ± 1.766 mm in men and 15.884 ± 1.694 mm in women. Significant intersex differences were observed for all mean diameters and lengths. Multilinear regression analysis showed that age, sex, and body surface area impacted mean diameters of all measured sites except aorta and common iliac artery length. Between male and female patients matched for body surface area, there were significant intersex differences for all measured sites, except for common iliac artery length.

Conclusions

The mean diameter of the abdominal aorta in this healthy cohort was 17.490 ± 2.110 mm overall, 18.377 ± 1.766 mm in men, and 15.884 ± 1.694 mm in women. Arterial diameter increased with male sex, older age, and increased body surface area, and aortic diameters were larger in men than in women with the same body surface area.

The Presence of Simple Renal Cysts Is Associated With Increased Arterial Stiffness in Patients With Abdominal Aortic Aneurysm

Simple renal cysts (SRC) are associated with the development of abdominal aortic aneurysms (AAA). We hypothesized that patients with AAA and SRC have increased arterial stiffness (AS) compared with patients without SRC. Patients (n=223) with an infrarenal AAA undergoing pulse wave analysis were recruited. Brachial-ankle pulse wave velocity (PWV) was measured (automated oscillometric method) as an index of AS. Participants were categorized into those with increased AS and those with normal/borderline AS (threshold: 1800 cm/s); 134 patients (60.1%) had increased AS and 89 (39.9%) patients had normal/borderline AS. Multivariable analyses showed that age ≥75 years (odds ratio [OR], 2.83; 95% confidence interval [CI], 1.51-5.72; P=.002), systolic blood pressure ≥140 mmHg (OR, 5.05; 95% CI, 2.35-10.83; P<.001), hypertension (OR, 2.28; 95% CI, 1.08-4.79; P=.030), and presence of SRC (OR, 1.89; 95% CI, 1.03-3.46; P=.040) were independent risk factors for increased AS. The presence of SRC is an independent risk factor for increased AS in patients with an AAA. This association suggests that patients with SRC may have severe aortic wall degeneration and thus the presence of SRC may be pathologically linked to the development of AAA.

The burden of aortic aneurysm in China from 1990 to 2019: findings from the Global Burden of Disease Study 2019

BACKGROUND

Aortic aneurysm (AA) is a global public health concern. However, little is known about the disease burden of AA in China.

METHODS

Following the general analytic strategy used in the Global Burden of Disease Study (GBD) 2019, we analyzed the mortality and years of life lost (YLLs) due to AA, stratified by sex, age, and province-level region in China from 1990 to 2019. The temporal trend of AA burden in China was analyzed and the main attributable risk factors for AA in China were also explored.

RESULTS

In China, the total AA deaths were 17,038 (95% UI: 14,392-19,980) in 2019, an increase of 136.1% compared with that in 1990, with an age-standardized death rate (ASDR) of 0.93 (95% UI: 0.79-1.08) per 100,000 person-years in 2019, a decrease of 6.8%. Meanwhile AA caused 378,578 (95% UI: 315,980-450,479) YLLs in 2019, an increase of 102.6% compared with that in 1990, with a crude YLL rate of 26.6 (95% UI: 22.2-31.7) per 100,000 person-years, an increase of 68.6%. The AA mortality and YLLs were higher in males than in females. AA caused most YLLs in the 65- to 75-year-old age group. The AA mortality and YLLs varied significantly among provinces in China, and the change in ASDR showed a negative correlation with the sociodemographic index of different provinces, namely, more decline of ASDR in developed provinces. High systolic blood pressure was shown to be the most significant attributable risk factor for AA burden in both males and females, and smoking was another major attributable risk factor, especially in males.

CONCLUSIONS

The disease burden of AA increased significantly from 1990 to 2019 in China, with higher mortality and YLLs in males, senior populations, and among residents of most western provinces in China. High systolic blood pressure and smoking were two major attributable risk factors for AA mortality in China.

Inhibition of XIST attenuates abdominal aortic aneurysm in mice by regulating apoptosis of vascular smooth muscle cells through miR-762/MAP2K4 axis

Abdominal aortic aneurysm (AAA) is a common chronic aortic degenerative disease. Long non-coding RNA X-inactive specific transcript (XIST) is associated with the progression of AAA, while the underlying mechanism is still unclear. We investigated the functional role of XIST in AAA. AAA mouse model was established by administration of Angiotensin II (Ang II). Primary mouse vascular smooth muscle cells (VSMCs) were separated from the abdominal aorta of Ang II-induced AAA mice, and then treated with Ang II. XIST was highly expressed in Ang II-treated VSMCs. Cell proliferation ability was decreased and apoptosis was increased in VSMCs following Ang II treatment. XIST knockdown reversed the impact of Ang II on cell proliferation and apoptosis in VSMCs. XIST promoted mitogen-activated protein kinase kinase 4 (MAP2K4) expression by sponging miR-762. XIST overexpression suppressed cell proliferation and apoptosis of Ang II-treated VSMCs by regulating miR-762/MAP2K4 axis. Finally, Ang II-induced AAA mouse model was established to verify the function of XIST in AAA. Inhibition of XIST significantly attenuated the pathological changes of abdominal aorta tissues in Ang II-induced mice. The expression of miR-762 was inhibited, and MAP2K4 expression was enhanced by XIST knockdown in the abdominal aorta tissues of AAA mice. In conclusion, these data demonstrate that inhibition of XIST attenuates AAA in mice, which attributes to inhibit apoptosis of VSMCs by regulating miR-762/MAP2K4 axis. Thus, this study highlights a novel ceRNA circuitry involving key regulators in the pathogenesis of AAA.

Protocol for the Metformin Aneurysm Trial (MAT): a placebo-controlled randomised trial testing whether metformin reduces the risk of serious complications of abdominal aortic aneurysm

Background

Multiple observational studies have associated metformin prescription with reduced progression of abdominal aortic aneurysm (AAA). The Metformin Aneurysm Trial (MAT) will test whether metformin reduces the risk of AAA rupture-related mortality or requirement for AAA surgery (AAA events) in people with asymptomatic aneurysms.

Methods

MAT is an international, multi-centre, prospective, parallel-group, randomised, placebo-controlled trial. Participants must have an asymptomatic AAA measuring at least 35 mm in maximum diameter, no diabetes, no contraindication to metformin and no current plans for surgical repair. The double-blind period is preceded by a 6-week, single-blind, active run-in phase in which all potential participants receive metformin. Only patients tolerating metformin by taking at least 80% of allocated medication will enter the trial and be randomised to 1500 mg of metformin XR or an identical placebo. The primary outcome is the proportion of AAA events defined as rupture-related mortality or need for surgical repair. Secondary outcomes include AAA growth, major adverse cardiovascular events and health-related quality of life. In order to test if metformin reduced the risk of AAA events by at least 25%, 616 primary outcome events will be required (power 90%, alpha 0.05).

Discussion

Currently, there is no drug therapy for AAA. Past trials have found no convincing evidence of the benefit of multiple blood pressure lowering, antibiotics, a mast cell inhibitor, an anti-platelet drug and a lipid-lowering medication on AAA growth. MAT is one of a number of trials now ongoing testing metformin for AAA. MAT, unlike these other trials, is designed to test the effect of metformin on AAA events. The international collaboration needed for MAT will be challenging to achieve given the current COVID-19 pandemic. If this challenge can be overcome, MAT will represent a trial unique within the AAA field in its large size and design.

Trial registration

Australian Clinical Trials ACTRN12618001707257. Registered on 16 October 2018

The prognostic impact of vascular calcification on abdominal aortic aneurysm progression

OBJECTIVE

The maximal aortic diameter is currently the only clinically applied predictor of abdominal aortic aneurysm (AAA) progression. It is known that risk of rupture is associated with aneurysm size, hence accurate monitoring of AAA expansion is crucial. Aneurysmal vessel wall calcification and its implication on AAA expansion are insufficiently explored. We evaluated the vascular calcification using longitudinal computed tomography angiographies (CTA) of AAA patients and its association with AAA growth.

METHODS

We conducted a retrospective study of 102 AAA patients with a total number of 389 abdominal CTAs at six-month intervals, treated and followed-up at the Division of Vascular Surgery, Department of General Surgery, Medical University of Vienna. Digitally stored CTAs were reviewed for vascular calcification (volume and score) of the infrarenal aorta and common iliac arteries as well as for morphometric AAA analysis. In the prognostic setting, slow versus fast AAA progression was defined as < 2 or ≥ 2 mm increase in AAA diameter over six months. In addition, to analyze the association of vascular calcification and AAA growth rate with longitudinal monitoring data, a specifically tailored log-linear mixed model was employed.

RESULTS

An inverse relation of increased abdominal vessel wall calcification and short-term AAA progression was detected. Compared to fast progressing AAA, the median calcification volume of the infrarenal aorta (1225.3 vs 519.8 mm³, P = 0.003), the median total calcification volume (2014.1 vs 1434.9 mm³, P = 0.008) and the median abdominal total customized Agatston calcium (cAC) score (1663.5 vs 718.4, P = 0.003) were significantly increased in slow progressing AAA. Importantly, a log-linear mixed model efficiently predicted AAA expansion based on current diameter and abdominal total cAC score (P = 0.042).

CONCLUSION

We assessed the prognostic value of CTA-measured vascular calcification for AAA progression. Increased vascular calcification stabilizes the aortic aneurysmal wall and likely protects against progressive AAA expansion, resulting in a significant decrease of aneurysm growth over time. As a consequence, this may have implications for rupture risk, mortality, morbidity, and cost.

Profile of the Ovation ALTO abdominal stent graft for the treatment of abdominal aortic aneurysms: overview of its safety and efficacy

INTRODUCTION

The Ovation ALTO is the next generation aortic stent graft from Endologix for the treatment of infra-renal abdominal aortic aneurysms. The device uses polymer-injected rings to create a proximal seal at the aneurysm neck.

AREAS COVERED

Results from the first clinical study of the ALTO graft are analyzed and the potential benefits of the graft in minimizing post-treatment aneurysmal neck dilation discussed. The implications of the ALTO's Instructions-For-Use (IFU) and low-profile delivery system are also reviewed.

EXPERT OPINION

The re-positioning of the sealing rings higher on the graft and an integrated compliant balloon are the most significant improvements on the Ovation iX, facilitating accurate placement of the proximal sealing ring and prompt balloon dilation of the polymer rings. The expansion the IFU to include neck lengths of ≥7 mm will mean more patients are eligible for infra-renal EVAR within IFU with the ALTO device. The published data on the device to date is limited. With over 1000 implants worldwide we would hope for more published data to become available. If this demonstrates similar mid-term results to that seen with the Ovation iX in arguably more hostile neck anatomy, then the Ovation ALTO is likely to be more widely used.

Prevalence of abdominal aortic aneurysms in patients with lung cancer

OBJECTIVE

Concomitance of abdominal aortic aneurysm (AAA) and primary lung cancer (LC) is not uncommon due to several shared risk factors. To evaluate the incidence of this association, analysis of the National Inpatient Sample database was utilized.

METHODS

A retrospective analysis of the National Inpatient Sample database between 2014 and 2018 for all patients diagnosed with primary LC was performed. The differences in the reported findings between the LC and control groups were assessed using the Pearson χ², Fisher exact, Student t, and/or Mann-Whitney U tests where appropriate. Multivariable logistic regression analysis was conducted to determine independent predictors of the presence of documented AAA.

RESULTS

A total of 158,904 patients were identified. Of these, 2430 patients (1.53%) were diagnosed with AAA and 156,474 (98.47%) without AAA. In the multivariable model, LC patients had higher odds of AAA compared with the general population (odds ratio, 1.43; 95% confidence interval, 1.35-1.51). In all age groups, female smokers had a higher rate of AAA compared with female nonsmokers (age <60 years, 0.13% vs 0.04%; 60-69 years, 0.77% vs 0.34%; 70-79 years, 1.65% vs 0.69%; and >80 years, 2.63% vs 1.31%; all P < .001).

CONCLUSIONS

LC and AAA share similar risk factors, which may explain the higher AAA prevalence among patients with LC. Given the higher prevalence of AAA in smokers compared with nonsmokers across all age groups in both male and female patients with LC, further sex-based studies investigating the overall mortality and morbidity benefits of AAA screening among patients with LC are highly warranted. This consideration would potentially address the sex disparity in outcomes for AAA management.

Modalities of endovascular management for internal iliac artery aneurysms

BACKGROUND

Internal iliac artery aneurysms (IIAA) are uncommon. Open repair is technically challenging and has been associated with increased morbidity and mortality compared with repair of abdominal aortic aneurysms. The aim of this study is to assess the outcomes of endovascular treatment of IIAA and incidence of postoperative pelvic ischaemia.

METHODS

A single-centre retrospective analysis was performed for IIAAs treated with endovascular repair between January 2005 and December 2017. Aneurysm morphology, mode of presentation and operative technique were evaluated. Primary outcomes were 30-day mortality and incidence of pelvic ischaemia. Secondary outcomes were technical success, major complications and reintervention.

RESULTS

Twenty-nine IIAAs were treated in 23 patients with a mean age of 74 */- 9 years. Six patients had isolated IIAAs (26%); the remaining 17 patients had aortoiliac aneurysms. Five patients (22%) required emergent repair for ruptured IIAAs. Mean IIAA size was 4.1 cm */- 1.8 and ruptures occurred at mean 6.1 cm */- 2.6. Endovascular techniques used: stent graft occlusion of the internal iliac artery (IIA) ostium (n = 16), deployment of iliac branch device (n = 9), and other endovascular techniques (n = 4). The 30-day mortality was zero. Three patients (13%) experienced post-operative pelvic ischemia which were all minor chronic gluteal claudication after IIA occlusion. Primary technical success was achieved in 27 repairs (93%). There was one late reintervention (3%).

CONCLUSION

IIAAs are often asymptomatic and diagnosed incidentally, however, a significant proportion present emergently. Endovascular treatment is feasible for both ruptured and non-ruptured aneurysms with low perioperative morbidity, mortality and reintervention rates.

Editor's Choice - Association Between Metformin Prescription and Abdominal Aortic Aneurysm Growth and Clinical Events: a Systematic Review and Meta-Analysis

OBJECTIVE

A meta-analysis of the association between metformin prescription and abdominal aortic aneurysm (AAA) growth and events (rupture or surgical repair) was performed.

METHODS

Open source databases were searched for observational studies reporting the association between metformin prescription and AAA growth or events. Meta-analyses were performed using random effects models. The risk of bias of included studies was assessed using a quality assessment tool developed in a previous systematic review. Sensitivity analyses restricted to people with diabetes, leave one out analyses, and an individual patient risk factor adjusted sub-analysis were performed. Funnel plots assessed reporting bias.

RESULTS

Eight studies comprising 153 553 patients were included, of whom 35 240 were and 118 313 were not prescribed metformin. Pooled weighted mean (± standard deviation) AAA growth was significantly reduced in patients prescribed metformin (0.9 ± 0.4 mm/year) compared with those not receiving the medication (1.8 ± 0.4 mm/year; weighted mean difference [WMD] 0.8 mm/year, 95% confidence interval [CI] 0.5 - 1.1; p < .001; I² = 89%). Leave one out analysis suggested that the significance of findings did not change after removal of individual studies. A sub-analysis within people with diabetes suggested that metformin reduced AAA growth (WMD 0.7 mm/year, 95% CI 0.3 - 1.0). Metformin prescription was associated with a reduced risk of AAA events (risk ratio 0.6, 95% CI 0.4 - 0.9, p = .028). Three, four, and one studies had low, moderate, and high risk of bias, respectively. Individual patient data analysis suggested that metformin prescription slowed annual AAA growth by 0.5 mm/year (95% CI 0.2 - 0.7). The GRADE summary suggested that the certainty of evidence that metformin limited AAA growth and prevented AAA events was very low.

CONCLUSION

Observational studies suggest that metformin prescription is associated with a clinically important significant reduction in both growth and clinically relevant events in people with AAA. These findings support the need for randomised trials to examine the benefit of metformin.

The Potential Benefits and Costs of an Intensified Approach to Low Density Lipoprotein Cholesterol Lowering in People with Abdominal Aortic Aneurysm

OBJECTIVE

The aims of this study were to assess the incidence of major vascular events (MVE) and peripheral vascular events (PVE) in people with a small asymptomatic abdominal aortic aneurysm (AAA) and model the theoretical benefits and costs of an intensified low density lipoprotein cholesterol (LDL-C) lowering programme.

METHODS

A total of 583 participants with AAAs measuring 30 - 54 mm were included in this study. The control of LDL-C and prescription of lipid lowering drugs were assessed by dividing participants into approximately equal tertiles depending on their year of recruitment into the study. The occurrence of MVE (myocardial infarction, stroke, cardiovascular death, and coronary or non-coronary revascularisation) and PVE (non-coronary revascularisation, AAA repair, and major amputation) were recorded prospectively, and the incidence of these events was calculated using Kaplan-Meier analysis. The relative risk reduction reported for these events in a previous randomised control trial (RCT) was then applied to these figures to model the absolute risk reduction and numbers needed to treat (NTT) that could theoretically be achieved with a mean LDL-C lowering of 1 mmol/L. The maximum allowable expense for a cost effective intensive LDL-C lowering programme was estimated using a cost utility analysis.

RESULTS

At entry, only 28.5% of participants had an LDL-C of < 1.8 mmol/L and only 18.5% were prescribed a high potency statin (atorvastatin 80 mg or rosuvastatin 40 mg). The five year incidences of MVE and PVE were 38.1% and 44.7%, respectively. It was estimated that if the mean LDL-C of the cohort had been reduced by 1 mmol/L, this could have reduced the absolute risk of MVE and PVE by 6.5% (95% CI 4.4 - 8.7; NNT 15) and 5.3% (95% CI 1.4 - 7.5; NNT 19), respectively. It was estimated that the maximum allowable expense for a cost effective LDL-C lowering programme would be between $1 239 AUD (€768) and $1 582 AUD (€981) per person per annum over a five year period.

CONCLUSION

People with a small asymptomatic AAA are at high risk of MVE and PVE. This study provides evidence of the possible benefits and allowable expense for a cost effective intensive LDL-C lowering programme in this population.

Kallistatin limits abdominal aortic aneurysm by attenuating generation of reactive oxygen species and apoptosis

Inflammation, vascular smooth muscle cell apoptosis and oxidative stress are believed to play important roles in abdominal aortic aneurysm (AAA) pathogenesis. Human kallistatin (KAL; gene SERPINA4) is a serine proteinase inhibitor previously shown to inhibit inflammation, apoptosis and oxidative stress. The aim of this study was to investigate the role of KAL in AAA through studies in experimental mouse models and patients. Serum KAL concentration was negatively associated with the diagnosis and growth of human AAA. Transgenic overexpression of the human KAL gene (KS-Tg) or administration of recombinant human KAL (rhKAL) inhibited AAA in the calcium phosphate (CaPO₄) and subcutaneous angiotensin II (AngII) infusion mouse models. Upregulation of KAL in both models resulted in reduction in the severity of aortic elastin degradation, reduced markers of oxidative stress and less vascular smooth muscle apoptosis within the aorta. Administration of rhKAL to vascular smooth muscle cells incubated in the presence of AngII or in human AAA thrombus-conditioned media reduced apoptosis and downregulated markers of oxidative stress. These effects of KAL were associated with upregulation of Sirtuin 1 activity within the aortas of both KS-Tg mice and rodents receiving rhKAL. These results suggest KAL-Sirtuin 1 signalling limits aortic wall remodelling and aneurysm development through reductions in oxidative stress and vascular smooth muscle cell apoptosis. Upregulating KAL may be a novel therapeutic strategy for AAA.

Non-guideline-compliant endovascular abdominal aortic aneurysm repair in women is associated with increased mortality and reintervention compared with men

OBJECTIVE

Sex-based disparities in surgical outcomes have emerged as an important focus in contemporary healthcare delivery. Likewise, the appropriate usage of endovascular abdominal aortic aneurysm repair (EVAR) in the United States remains a subject of ongoing controversy, with a significant number of U.S. EVARs failing to adhere to the Society for Vascular Surgery (SVS) clinical practice guideline (CPG) diameter thresholds. The purpose of the present study was to determine the effect of sex among patients undergoing EVAR that was not compliant with the SVS CPGs.

METHODS

All elective EVAR procedures for abdominal aortic aneurysms without a concomitant iliac aneurysm (≥3.0 cm) in the SVS Vascular Quality Initiative were analyzed (2015-2019; n = 25,112). SVS CPG noncompliant repairs were defined as a size of <5.5 cm for men and <5.0 cm for women. The primary endpoint was 30-day mortality. The secondary endpoints were all-cause mortality, complications, and reintervention. Logistic regression was performed to control for surgeon- and patient-level factors. Freedom from the endpoints was determined using the Kaplan-Meier method.

RESULTS

Noncompliant EVAR was performed in 9675 patients (38.5%). Although men were significantly more likely to undergo such procedures (90% vs 10%; odds ratio [OR], 3.1; 95% confidence interval [CI], 2.9-3.4; P < .0001), the 30-day mortality was greater for the women than the men (1.8% vs 0.5%; P = .0003). Women also experienced significantly higher rates of multiple complications, including postoperative myocardial infarction (1% vs 0.3%; P = .006), respiratory failure (1.4% vs 0.6%; P = .01), intestinal ischemia (0.7% vs 0.2%; P = .003), access vessel hematoma (3% vs 1.2%; P = .0006), and iliac access vessel injury (2.4% vs 0.8%; P < .0001). Additionally, women experienced increased overall 1-year reintervention rates (11.5% vs 5.8%; P < .0001). In the adjusted analysis, 30-day mortality and any in-hospital complication risk remained significantly greater for the women (30-day death: OR, 3.1; 95% CI, 1.6-5.8; P = .0005; in-hospital complication: OR, 1.9; 95% CI, 1.4-2.6; P < .0001). Women also experienced increased reintervention rates over time compared with men (OR, 1.5; 95% CI, 1.1-2.2; P = .02).

CONCLUSIONS

Although men were more likely to undergo non-CPG compliant EVAR, women experienced increased short-term morbidity and 30-day mortality and higher rates of reintervention when undergoing non-CPG compliant EVAR. These unanticipated findings necessitate increased scrutiny of current U.S. sex-based EVAR practice and should caution against the use of non-CPG compliant EVAR for women.

Protocol for a randomised controlled trial for Treatment in Thoracic Aortic Aneurysm: Surgery versus Surveillance (TITAN: SvS)

INTRODUCTION

Ascending thoracic aortic aneurysm (ATAA) is an asymptomatic condition that can lead to catastrophic events of rupture or dissection. Current guidelines are based on limited retrospective data and recommend surgical intervention for ATAA with a diameter of greater or equal to 5.5 cm. Treatment in Thoracic Aortic Aneurysm: Surgery versus Surveillance is the first prospective, multicentre, randomised controlled trial that compares outcomes of patients undergoing early elective ascending aortic surgery to patients undergoing medical surveillance.

METHODS AND ANALYSIS

Patients between the ages of 18 and 80 with an asymptomatic ATAA between 5.0 cm and 5.4 cm in diameter are eligible for randomisation to early surgery or surveillance. Patients in the surgery group will be followed at 1 month after discharge, then annually for a minimum of 2 years and up to 5 years. Patients in the surveillance group will be followed annually from their index clinic visit for a minimum of 2 years and up to 5 years. The primary outcome is all-cause mortality at follow-up. A sample size of 618 subjects (309 in each group) will achieve an 80% power at a 0.047 significance level.

ETHICS AND DISSEMINATION

This study has received Ottawa Health Science Network Research Ethics Board approval (Protocol 20180007-01H), which was most recently updated on 25 November 2020. The Research Ethics Board have granted approval to the study at 14 participating institutions, including the Ottawa Health Science Network Research Ethics Board. On completion of data analysis, the result of the trial will be presented at national and international conferences, and published in relevant journals, regardless of the finding of the trial.

TRIAL REGISTRATION NUMBER

NCT03536312.

Association of Medicaid Expansion with In-Hospital Outcomes After Abdominal Aortic Aneurysm Repair

OBJECTIVES

Multiple studies have shown improved outcomes and higher utilization of care with the increase of insurance coverage. This study aims to assess whether Medicaid expansion (ME) has changed the utilization and outcomes of abdominal aortic aneurysm (AAA) repair in the United States.

DESIGN

Retrospective observational study.

MATERIALS

Data of patients undergoing AAA repair in the Vascular Quality Initiative (2010-2017).

METHODS

Interrupted time-series (ITS) analysis was utilized to evaluate changes in annual trends of postoperative outcomes after elective AAA repair before and after 2014. We also assessed if these trend changes were significant by comparing the changes in states which adopted ME in 2014 versus nonexpansion states (NME), and conducting a difference-in-difference analysis. Primary outcomes included in-hospital mortality and adverse events (bowel and leg ischemia, cardiac, renal, respiratory, stroke and return to the OR).

RESULTS

A total of 19,143 procedures were included (Endovascular: 85.8% and open: 14.2%), of which 40.9% were performed in ME States. Compared to preexpansion trends (P1), there was a 2% annual increase in elective AAA repair in ME states (P1: -1.8% versus P2: +0.2%, P< 0.01) with no significant change in NME (P1: +0.3% versus P2: +0.2%, P = 0.97). Among elective cases, annual trends in the use of EVAR increased by 2% in ME states (95% confidence interval (CI) = -0.1, 4.1, P = 0.06), compared to a 3% decrease in NME States [95%CI = -5.8, -0.6, P = 0.01) (P_MEversusNME < 0.01]. There was no association between ME and in-hospital mortality. Nonetheless, it was associated with a decrease in the annual trends of in-hospital complications (ME: -1.4% (-2.1,-0.8) versus NME: +0.2% (-0.2, +0.8), P < 0.01).

CONCLUSIONS

While no association between ME and increased survival was noted in states which adopted ME, there was a significant increase of elective AAA cases and EVAR utilization and a decrease in in-hospital complications in ME States.

Proteomics applications in biomarker discovery and pathogenesis for abdominal aortic aneurysm

Introduction: Abdominal aortic aneurysm (AAA) is a common, complex, and life-threatening disease. Currently, the pathogenesis of AAA is not well understood. No biomarkers or specific drugs are available for AAA in clinical applications. Proteomics is a powerful tool in biomarker discovery, exploration of pathogenesis, and drug target identification.Areas covered: We review the application of mass spectrometry-based proteome analysis in AAA patients within the last ten years. Differentially expressed proteins associated with AAA were identified in multiple sample sources, including vascular tissue, intraluminal thrombus, tissue secretome, blood, and cells. Some potential disease biomarkers, pathogenic mechanisms, or therapeutic targets for AAA were discovered using proteome analysis. The challenges and prospects of proteomics applied to AAA are also discussed.Expert opinion: Since most of the previous proteomic studies used relatively small sample sizes, some promising biomarkers need to be validated in multicenter cohorts to accelerate their clinical application. With the rapid development of mass spectrometry technology, modification-specific proteomics and multi-omics research in the future will enhance our understanding of the pathogenesis of AAA and promote biomarker discovery and drug development for clinical translation.

Aortic aneurysms and dissections: Unmet needs from physicians and engineers perspectives

The treatment of aortic disease is complex, requiring cardiothoracic and vascular surgeons to make pre-, post- and intraoperative decisions directly influencing patient survival and well-being. Despite tremendous advancement in vascular surgery and endovascular techniques in the last two decades, along with the abundance of research in the field, many unmet needs and unanswered questions remain. Tight collaboration between engineers and physicians is a keystone in translating new tools, techniques, and devices into practice. Here, we have gathered our perspective, as physicians and engineers, in several pressing issues associated with the diagnosis and treatment of aortic aneurysms and dissection, referring to the current knowledge and practice, signifying unmet needs as well as future directions.

Outcomes in Octogenarians and the Effect of Comorbidities After Intact Abdominal Aortic Aneurysm Repair in the Netherlands: A Nationwide Cohort Study

OBJECTIVE

Age is an independent risk factor for mortality after both elective open surgical repair (OSR) and endovascular aneurysm repair (EVAR). As a result of an ageing population, and the less invasive nature of EVAR, the number of patients over 80 years (octogenarians) being treated is increasing. The mortality and morbidity following aneurysm surgery are increased for octogenarians. However, the mortality for octogenarians who have either low or high peri-operative risks remains unclear. The aim of this study was to provide peri-operative outcomes of octogenarians vs. non-octogenarians after OSR and EVAR for intact aneurysms, including separate subanalyses for elective and urgent intact repair, based on a nationwide cohort. Furthermore, the influence of comorbidities on peri-operative mortality was examined.

METHODS

All patients registered in the Dutch Surgical Aneurysm Audit (DSAA) undergoing intact AAA repair between 2013 and 2018, were included. Patient characteristics and peri-operative outcomes (peri-operative mortality, and major complications) of octogenarians vs. non-octogenarians for both OSR and EVAR were compared using descriptive statistics. Multivariable logistic regression analyses were used to examine whether age and the presence of cardiac, pulmonary, or renal comorbidities were associated with mortality.

RESULTS

This study included 12 054 EVAR patients (3 015 octogenarians), and 3 815 OSR patients (425 octogenarians). Octogenarians in both the EVAR and OSR treatment groups were more often female and had more comorbidities. In both treatment groups, octogenarians had significantly higher mortality rates following intact repair as well as higher major complication rates. Mortality rates of octogenarians were 1.9% after EVAR and 11.8% after OSR. Age ≥ 80 and presence of cardiac, pulmonary, and renal comorbidities were associated with mortality after EVAR and OSR.

CONCLUSION

Because of the high peri-operative mortality rates of octogenarians, awareness of the presence of comorbidities is essential in the decision making process before offering aneurysm repair to this cohort, especially when OSR is considered.

Association of Metformin and Abdominal Aortic Aneurysm Repair Outcomes

BACKGROUND

Metformin is a commonly used drug in diabetes mellitus treatment. Recently it has been suggested that the use of metformin on diabetes mellitus patients may lower the prevalence and slow the progression of AAA (abdominal aortic aneurysm) as well as the risk of rupture related mortality. The aim of this studywas to investigate the impact of metformin treatment on the risk of AAA repair related mortality and surgical complications.

METHODS

In this retrospective study, the clinical data of 306 patients, including 77 patients with diabetes mellitus, who underwent abdominal aortic aneurysm repair has been analyzed. Treatment outcomes have been investigated. The diabetes and metformin prescription status has been obtained from the medical history. Patients were divided into three groups: diabetes-free individuals, diabetics treated with metformin and diabetics treated with other glucose lowering drugs. The association between metformin treatment and AAA diameter, surgical complications and mortality were assessed using chi-square independence test and odds ratio analysis. In order to assess which factors are influencing AAA repair related complications and mortality a multi-variables analysis has been performed.

RESULTS

A significant protective effect of metformin treatment towards AAA repair related mortality (P = 0.019) and complications (P = 0.032) among patients suffering from diabetes mellitus was revealed. These findings were statistically insignificant when considering all groups of patients (diabetes-free individuals, diabetics treated with metformin and diabetics treated with other glucose lowering drugs).

CONCLUSION

Metformin may lower the risk of AAA repair related mortality and surgical complications among patients with diabetes.

The Role of Imaging in Health Screening: Overview, Rationale of Screening, and Screening Economics

Imaging screening examinations are growing in their indications and volume to identify conditions at an early, treatable stage. The Radiology Research Alliance's 'Role of Imaging in Health Screening' Task Force provides a review of imaging-based screening rationale, economics, and describes established guidelines by various organizations. Various imaging modalities can be employed in screening, and are often chosen based on the specific pathology and patient characteristics. Prevalent disease processes with identifiable progression patterns that benefit from early potentially curative interventions are ideal for screening. Two such examples include colonic precancerous polyp progression to adenocarcinoma in colon cancer formation and atypical ductal hyperplasia progression to ductal carcinoma in situ and invasive ductal carcinoma in breast cancer. Economic factors in imaging-based screening are reviewed, including in the context of value-based reimbursements. Global differences in screening are outlined, along with the role of various organizational guidelines, including the American Cancer Society, the US Preventive Services Task Force, and the American College of Radiology.

Evaluating Growth Patterns of Abdominal Aortic Aneurysm Diameter With Serial Computed Tomography Surveillance

Importance

Small abdominal aortic aneurysms (AAAs) are common in the elderly population. Their growth rates and patterns, which drive clinical surveillance, are widely disputed.

Objective

To assess the growth patterns and rates of AAAs as documented on serial computed tomography (CT) scans.

Design, Setting, and Participants

Cohort study and secondary analysis of the Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA3CT), a randomized, double-blind placebo-controlled clinical trial conducted from 2013 to 2018, with CT imaging every 6 months for 2 years. The trial was a multicenter, observational secondary analysis, not related to treatment hypotheses of data collected in the N-TA3CT. Participants included 254 patients with baseline AAA diameter between 3.5 and 5.0 cm.

Exposures

Patients received serial CT scan measurements, analyzed for maximum transverse diameter, at 6-month intervals.

Main Outcomes and Measures

The primary study outcome was AAA annual growth rate. Secondary analyses included characterizing AAA growth patterns, assessing likelihood of AAA diameter to exceed sex-specific intervention thresholds over 2 years.

Results

A total of 254 patients, 35 women with baseline AAA diameter 3.5 to 4.5 cm and 219 men with baseline diameter 3.5 to 5.0 cm, were included. Yearly growth rates of AAA diameters were a median of 0.17 cm/y (interquartile range [IQR], 0.16) and a mean (SD), 0.19 (0.14) cm/y. Ten percent of AAAs displayed minimal to no growth (<0.05 cm/y), 62% displayed low growth (0.05-0.25 cm/y), and 28% displayed high growth (>0.25 cm/y). Baseline AAA diameter accounted for 5.4% of variance of growth rate (P < .001; R2, 0.054). Most AAAs displayed linear growth (70%); large variations in interval growth rates occurred infrequently (3% staccato growth and 4% exponential growth); and some patients' growth patterns were not clearly classifiable (23% indeterminate). No patients with a maximum transverse diameter less than 4.25 cm exceeded sex-specific repair thresholds at 2 years (men, 0 of 92; 95% CI, 0.00-0.055; women, 0 of 25 ; 95% CI, 0.00-0.247). Twenty-six percent of patients with a maximum transverse diameter of at least 4.25 cm exceeded sex-specific repair thresholds at 2 years (n = 12 of 83 men with diameter ranging from 4.25 to <4.75 cm; 95% CI, 0.091-0.264; n = 21 of 44 men with diameter ranging from 4.75-5.0 cm; 95% CI, 0.362-0.669; n = 3 of 10 women with diameter ≥4.25 cm; 95% CI, 0.093-0.726).

Conclusions and Relevance

Most small AAAs showed linear growth; large intrapatient variations in interval growth rates were infrequently observed over 2 years. Linear growth modeling of AAAs in individual patients suggests smaller AAAs (<4.25 cm) can be followed up with a CT scan in at least 2 years with little chance of exceeding interventional thresholds.

Trial Registration

ClinicalTrials.gov Identifier: NCT01756833.

Evaluating the Cost-Effectiveness of Changes to the Surveillance Intervals in the UK Abdominal Aortic Aneurysm Screening Programme

OBJECTIVES

To investigate the safety and cost-effectiveness of lengthening the time between surveillance ultrasound scans in the UK Abdominal Aortic Aneurysm (AAA) Screening Programme.

METHODS

A discrete event simulation model was used to evaluate the cost-effectiveness of AAA screening for men aged 65, comparing current surveillance intervals to 6 alternative surveillance interval strategies that lengthened the time between surveillance scans for 1 or more AAA size categories. The model considered clinical events and costs incurred over a 30-year time horizon and the cost per quality-adjusted life year (QALY). The model adopted the National Health Service perspective and discounted future costs and benefits at 3.5%.

RESULTS

Compared with current practice, alternative surveillance strategies resulted in up to a 4% reduction in the number of elective AAA repairs but with an increase of up to 1.6% in the number of AAA ruptures and AAA-related deaths. Alternative strategies resulted in a small reduction in QALYs compared to current practice but with reduced costs. Two strategies that lengthened surveillance intervals in only very small AAAs (3.0-3.9 cm) provided, at a cost-effectiveness threshold of £20 000 per QALY, the highest positive incremental net benefit. There was negligible chance that current practice is the most cost-effective strategy at any threshold below £40 000 per QALY.

CONCLUSIONS

Lengthening surveillance intervals in the UK Abdominal Aortic Aneurysm Screening Programme, especially for small AAA, can marginally reduce the incremental cost per QALY of the program. Nevertheless, whether the cost savings from refining surveillance strategies justifies a change in clinical practice is unclear.

A comparison of subjective clinical and objective judgement of abdominal aortic aneurysm morphology

BACKGROUND

We compared the subjective, clinical judgement of "saccular" morphology with the objective judgement of mechanical structural analysis.

METHODS

Using structural analysis with the finite element method, we previously created a simple model of abdominal aortic aneurysm (AAA) that visualized the distribution of the maximum principal stress (MPS) in the aortic wall and identified the area of prominent stress. AAA "saccular" morphology was determined according to the area showing MPS>0.03 MPa. AAAs with low aspect ratio (horizontally long AAA sac) and small fillet radius were defined as "saccular." Twelve vascular surgeons were recruited. First, they judged the AAA as saccular or fusiform with 3-dimensional images at their clinical impression (subjective "eyeball" judgement). Second, they applied the deformable figure tools on the simple AAA-shaped sagittal view in the application model for 30 AAA cases. From the data of the tools applied, the mechanical structural analysis was performed semi-automatically and the morphology was judged with the objective "simple application."

RESULTS

The structural analysis revealed that only one case was judged as saccular by 11 out of 12 surgeons and the other 29 AAAs were judged as fusiform by two-thirds or more of the surgeons. In contrast, 5 cases were subjectively judged as saccular by eight and more of the surgeons.

CONCLUSIONS

The clinical judgement of AAA saccular morphology by the vascular surgeons was different from the judgement derived from the mechanical structural analysis using the application model. The saccular morphology may be theoretically rare in AAAs.

FRZB as a key molecule in abdominal aortic aneurysm progression affecting vascular integrity

Abdominal aortic aneurysm (AAA), when ruptured, results in high mortality. The identification of molecular pathways involved in AAA progression is required to improve AAA prognosis. The aim of the present study was to assess the key genes for the progression of AAA and their functional role. Genomic and clinical data of three independent cohorts were downloaded from the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) (GSE57691, GSE7084, and GSE98278). To develop AAA diagnosis and progression-related differentially expressed genes (DEGs), we used a significance analysis of microarray (SAM). Spearman correlation test and gene set analysis were performed to identify potential enriched pathways for DEGs. Only the Frizzled-related protein (FRZB) gene and chromosome 1 open reading frame 24 (C1orf24) exhibited significant down-regulation in all analyses. With FRZB, the pathways were associated with RHO GTPase and elastin fiber formation. With C1orf24, the pathways were elastic fiber formation, extracellular matrix organization, and cell–cell communication. Since only FRZB was evolutionally conserved in the vertebrates, function of FRZB was validated using zebrafish embryos. Knockdown of frzb remarkably reduced vascular integrity in zebrafish embryos. We believe that FRZB is a key gene involved in AAA initiation and progression affecting vascular integrity.

The Association Between Curvature and Rupture in a Murine Model of Abdominal Aortic Aneurysm and Dissection

BACKGROUND

Mouse models of abdominal aortic aneurysm (AAA) and dissection have proven to be invaluable in the advancement of diagnostics and therapeutics by providing a platform to decipher response variables that are elusive in human populations. One such model involves systemic Angiotensin II (Ang-II) infusion into low density-lipoprotein receptor-deficient (LDLr-/-) mice leading to intramural thrombus formation, inflammation, matrix degradation, dilation, and dissection. Despite its effectiveness, considerable experimental variability has been observed in AAAs taken from our Ang-II infused LDLr-/- mice (n=12) with obvious dissection occurring in 3 samples, outer bulge radii ranging from 0.73 to 2.12 mm, burst pressures ranging from 155 to 540 mmHg, and rupture location occurring 0.05 to 2.53 mm from the peak bulge location.

OBJECTIVE

We hypothesized that surface curvature, a fundamental measure of shape, could serve as a useful predictor of AAA failure at supra-physiological inflation pressures.

METHODS

To test this hypothesis, we fit well-known biquadratic surface patches to 360° micro-mechanical test data and used Spearman's rank correlation (rho) to identify relationships between failure metrics and curvature indices.

RESULTS

We found the strongest associations between burst pressure and the maximum value of the first principal curvature (rho=-0.591, p-val=0.061), the maximum value of Mean curvature (rho=-0.545, p-val=0.087), and local values of Mean curvature at the burst location (rho=-0.864, p-val=0.001) with only the latter significant after Bonferroni correction. Additionally, the surface profile at failure was predominantly convex and hyperbolic (saddle-shaped) as indicated by a negative sign in the Gaussian curvature. Findings reiterate the importance of shape in experimental models of AAA.

A Novel Hypothesis: A Role for Follicle Stimulating Hormone in Abdominal Aortic Aneurysm Development in Postmenopausal Women

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta, which can potentially be fatal due to exsanguination following rupture. Although AAA is less prevalent in women, women with AAA have a more severe AAA progression compared to men as reflected by enhanced aneurysm growth rates and a higher rupture risk. Women are diagnosed with AAA at an older age than men, and in line with increased osteoporosis and cardiovascular events, the delayed AAA onset has been attributed to the reduction of the protective effect of oestrogens during the menopausal transition. However, new insights have shown that a high follicle stimulating hormone (FSH) level during menopause may also play a key role in those diseases. In this report we hypothesize that FSH may aggravate AAA development and progression in postmenopausal women via a direct and/or indirect role, promoting aorta pathology. Since FSH receptors (FSHR) are reported on many other cell types than granulosa cells in the ovaries, it is feasible that FSH stimulation of FSHR-bearing cells such as aortic endothelial cells or inflammatory cells, could promote AAA formation directly. Indirectly, AAA progression may be influenced by an FSH-mediated increase in osteoporosis, which is associated with aortic calcification. Also, an FSH-mediated decrease in cholesterol uptake by the liver and an increase in cholesterol biosynthesis will increase the cholesterol level in the circulation, and subsequently promote aortic atherosclerosis and inflammation. Lastly, FSH-induced adipogenesis may lead to obesity-mediated dysfunction of the microvasculature of the aorta and/or modulation of the periaortic adipose tissue. Thus the long term increased plasma FSH levels during the menopausal transition may contribute to enhanced AAA disease in menopausal women and could be a potential novel target for treatment to lower AAA-related events in women.

Role of Adipokines and Perivascular Adipose Tissue in Abdominal Aortic Aneurysm: A Systematic Review and Meta-Analysis of Animal and Human Observational Studies

Improved understanding of abdominal aortic aneurysms (AAA) pathogenesis is required to identify treatment targets. This systematic review summarized evidence from animal studies and clinical research examining the role of adipokines and perivascular adipose tissue (PVAT) in AAA pathogenesis. Meta-analyses suggested that leptin (Standardized mean difference [SMD]: 0.50 [95% confidence interval (CI): -1.62, 2.61]) and adiponectin (SMD: -3.16 [95% CI: -7.59, 1.28]) upregulation did not significantly affect AAA severity within animal models. There were inconsistent findings and limited studies investigating the effect of resistin-like molecule-beta (RELMβ) and PVAT in animal models of AAA. Clinical studies suggested that circulating leptin (SMD: 0.32 [95% CI: 0.19, 0.45]) and resistin (SMD: 0.63 [95% CI 0.50, 0.76]) concentrations and PVAT to abdominal adipose tissue ratio (SMD: 0.56 [95% CI 0.33, 0.79]) were significantly greater in people diagnosed with AAA compared to controls. Serum adiponectin levels were not associated with AAA diagnosis (SMD: -0.62 [95% CI -1.76, 0.52]). One, eight, and one animal studies and two, two, and four human studies had low, moderate, and high risk-of-bias respectively. These findings suggest that AAA is associated with higher circulating concentrations of leptin and resistin and greater amounts of PVAT than controls but whether this plays a role in aneurysm pathogenesis is unclear.

Global Burden of Cardiovascular Diseases and Risk Factors, 1990-2019: Update From the GBD 2019 Study

Cardiovascular diseases (CVDs), principally ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and a major contributor to disability. This paper reviews the magnitude of total CVD burden, including 13 underlying causes of cardiovascular death and 9 related risk factors, using estimates from the Global Burden of Disease (GBD) Study 2019. GBD, an ongoing multinational collaboration to provide comparable and consistent estimates of population health over time, used all available population-level data sources on incidence, prevalence, case fatality, mortality, and health risks to produce estimates for 204 countries and territories from 1990 to 2019. Prevalent cases of total CVD nearly doubled from 271 million (95% uncertainty interval [UI]: 257 to 285 million) in 1990 to 523 million (95% UI: 497 to 550 million) in 2019, and the number of CVD deaths steadily increased from 12.1 million (95% UI:11.4 to 12.6 million) in 1990, reaching 18.6 million (95% UI: 17.1 to 19.7 million) in 2019. The global trends for disability-adjusted life years (DALYs) and years of life lost also increased significantly, and years lived with disability doubled from 17.7 million (95% UI: 12.9 to 22.5 million) to 34.4 million (95% UI:24.9 to 43.6 million) over that period. The total number of DALYs due to IHD has risen steadily since 1990, reaching 182 million (95% UI: 170 to 194 million) DALYs, 9.14 million (95% UI: 8.40 to 9.74 million) deaths in the year 2019, and 197 million (95% UI: 178 to 220 million) prevalent cases of IHD in 2019. The total number of DALYs due to stroke has risen steadily since 1990, reaching 143 million (95% UI: 133 to 153 million) DALYs, 6.55 million (95% UI: 6.00 to 7.02 million) deaths in the year 2019, and 101 million (95% UI: 93.2 to 111 million) prevalent cases of stroke in 2019. Cardiovascular diseases remain the leading cause of disease burden in the world. CVD burden continues its decades-long rise for almost all countries outside high-income countries, and alarmingly, the age-standardized rate of CVD has begun to rise in some locations where it was previously declining in high-income countries. There is an urgent need to focus on implementing existing cost-effective policies and interventions if the world is to meet the targets for Sustainable Development Goal 3 and achieve a 30% reduction in premature mortality due to noncommunicable diseases.