Quantifying the risks of hypertension, age, sex and smoking in patients with abdominal aortic aneurysm

A Comprehensive Review on Computational Analysis, Research Advances, and Major Findings on Abdominal Aortic Aneurysms for the Years 2021 to 2023

BACKGROUND

Abdominal aortic aneurysm (AAA) is a pathological condition characterized by the dilation of the lower part of the aorta, where significant hemodynamic forces are present. The prevalence and high mortality risk associated with AAA remain major concerns within the scientific community. There is a critical need for extensive research to understand the underlying mechanisms, pathophysiological characteristics, and effective detection methods for abdominal aortic abnormalities. Additionally, it is imperative to develop and refine both medical and surgical management strategies. This review aims to indicate the role of computational analysis in the comprehension and management of AAAs and covers recent research studies regarding the computational analysis approach conducted between 2021 and 2023. Computational analysis methods have emerged as sophisticated and noninvasive approaches, providing detailed insights into the complex dynamics of AAA and enhancing our ability to study and manage this condition effectively.

METHODS

Computational analysis relies on fluid mechanics principles applied to arterial flow, using the Navier-Stokes equations to model blood flow dynamics. Key hemodynamic indicators relevant to AAAs include Time-Average Wall Shear Stress, Oscillatory Shear Index, Endothelial Cell Activation Potential, and Relative Residence Time. The primary methods employed for simulating the abdominal aorta and studying its biomechanical environment are computational fluid dynamics and Finite Element Methods. This review article encompasses a thorough examination of recent literature, focusing on studies conducted between 2021 and 2023.

RESULTS

The latest studies have elucidated crucial insights into the blood flow characteristics and geometric attributes of AAAs. Notably, blood flow patterns within AAAs are associated with increased rupture risk, along with elevated intraluminal thrombus volume and specific calcification thresholds. Asymmetric AAAs exhibit heightened risks of rupture and thrombus formation due to low and oscillating wall shear stresses. Moreover, larger aneurysms demonstrate increased wall stress, pressure, and energy loss. Advanced modeling techniques have augmented predictive capabilities concerning growth rates and surgical thresholds. Additionally, the influence of material properties and thrombus volume on wall stress levels is noteworthy, while inlet velocity profiles significantly modulate blood flow dynamics within AAAs.

CONCLUSIONS

This review highlights the potential utility of computational modeling. However, the clinical applicability of computational modeling has been limited by methodological variability despite the ongoing accumulation of evidence supporting the prognostic significance of biomechanical and hemodynamic indices in this field. The establishment of standardized reporting is critical for clinical implementation.

The potential of a nomogram risk assessment model for the diagnosis of abdominal aortic aneurysm: a multicenter retrospective study

The incidence of abdominal aortic aneurysm (AAA) is very high, but there is no risk assessment model for early identification of AAA in clinic. The aim of this study was to develop a nomogram risk assessment model for predicting AAA. The data of 280 patients diagnosed as AAA and 385 controls in The Affiliated Suzhou Hospital of Nanjing Medical University were retrospectively reviewed. The LASSO regression method was applied to filter variables, and multivariate logistic regression was used to construct a nomogram. The discriminatory ability of the model was determined by calculating the area under the curve (AUC). The calibration capability of the model is evaluated by using bootstrap (resampling = 1000) internal validation and Hosmer-Lemeshow test. The clinical utility and clinical application value were evaluated by decision curve analysis (DCA) and clinical impact curve (CIC). In addition, a retrospective review of 133 AAA patients and 262 controls from The First Affiliated Hospital of Soochow University was performed as an external validation cohort. Eight variables are selected to construct the nomogram of AAA risk assessment model. The nomogram predicted AAA with AUC values of 0.928 (95%CI, 0.907-0.950) in the training cohort, and 0.902 (95%CI, 0.865-0.940) in the external validation cohort, the risk prediction model has excellent discriminative ability. The calibration curve and Hosmer-Lemeshow test proved that the nomogram predicted outcomes were close to the ideal curve, the predicted outcomes were consistent with the real outcomes, the DCA curve and CIC curve showed that patients could benefit. This finding was also confirmed in the external validation cohort. In this study, a nomogram was constructed that incorporated eight demographic and clinical characteristics of AAA patients, which can be used as a practical approach for the personalized early screening and auxiliary diagnosis of the potential risk factors.

Editor's Choice - Prevalence of Smoking and Impact on Peri-Operative Outcomes After Elective Abdominal Aortic Aneurysm Repair

OBJECTIVE

The contemporary burden of smoking in patients undergoing elective abdominal aortic aneurysm (AAA) repair in the UK is unknown. This study aimed to quantify the prevalence of smoking in patients undergoing AAA repair in the UK and determine the association between smoking and peri-operative outcomes.

METHODS

This was an observational cohort study. The National Vascular Registry was interrogated for adults undergoing elective infrarenal AAA repair from 2014 to 2021 for prevalence of current smokers, former smokers, and non-smokers over time. The primary outcomes were post-operative complications by smoking status. Secondary outcomes were variation in smoking rates over time and by hospital, in hospital mortality, and length of stay by smoking status. All analyses were adjusted using the validated British Aneurysm Repair score.

RESULTS

Overall, 26 916 patients undergoing elective AAA repair were included (21.9% smokers, 62.2% former smokers, 15.9% non-smokers). The prevalence of smoking did not change over time, with a 2.4 fold variation between UK hospitals (range 13.0 - 31.8% excluding outliers). In hospital mortality was not significantly different between smokers, former smokers, and non-smokers (p > .050 for all comparisons). Compared with non-smokers, smoking was associated with increased overall (odds ratio [OR] 1.40, 95% confidence interval [CI] 1.24 - 1.57) and respiratory complications (OR 1.98, 95% CI 1.63 - 2.39), limb ischaemia (OR 1.63, 95% CI 1.19 - 2.23), bowel ischaemia (OR 1.64, 95% CI 1.06 - 2.54), return to theatre (OR 1.38, 95% CI 1.11 - 1.71), and intensive care admission (OR 1.43, 95% CI 1.31 - 1.56). Compared with former smokers, smoking was associated with increased overall (OR 1.24, 95% CI 1.14 - 1.36), respiratory (OR 1.44, 95% CI 1.27 - 1.63) and limb ischaemia complications (OR 1.48, 95% CI 1.19 - 1.84), and intensive care admission (OR 1.37, 95% CI 1.28 - 1.46). On analysis of the endovascular aneurysm repair subgroup, active smoking was associated with significantly higher rates of limb ischaemia compared with former and non-smokers (OR 2.12, 95% CI 1.49 - 3.01 and OR 1.94, 95% CI 1.19 - 3.16 respectively).

CONCLUSION

The prevalence of smoking remains high in patients undergoing elective AAA repair with no evidence of a decline in active smokers from 2014 to 2021 compared with the general UK population. Smoking is associated with increased peri-operative complication rates.

Implantable Pressure-Sensing Devices for Monitoring Abdominal Aortic Aneurysms in Post-Endovascular Aneurysm Repair

Over the past two decades, there has been extensive research into surveillance methods for the post-endovascular repair of abdominal aortic aneurysms, highlighting the importance of these technologies in supplementing or even replacing conventional image-screening modalities. This review aims to provide an overview of the current status of alternative surveillance solutions for endovascular aneurysm repair, while also identifying potential aneurysm features that could be used to develop novel monitoring technologies. It offers a comprehensive review of these recent clinical advances, comparing new and standard clinical practices. After introducing the clinical understanding of abdominal aortic aneurysms and exploring current treatment procedures, the paper discusses the current surveillance methods for endovascular repair, contrasting them with recent pressure-sensing technologies. The literature on three commercial pressure-sensing devices for post-endovascular repair surveillance is analyzed. Various pre-clinical and clinical studies assessing the safety and efficacy of these devices are reviewed, providing a comparative summary of their outcomes. The review of the results from pre-clinical and clinical studies suggests a consistent trend of decreased blood pressure in the excluded aneurysm sac post-repair. However, despite successful pressure readings from the aneurysm sac, no strong link has been established to translate these measurements into the presence or absence of endoleaks. Furthermore, the results do not allow for a conclusive determination of ongoing aneurysm sac growth. Consequently, a strong clinical need persists for monitoring endoleaks and aneurysm growth following endovascular repair.

The potential involvement of glycocalyx disruption in abdominal aortic aneurysm pathogenesis

BACKGROUND

Abdominal aortic aneurysm is a weakening and expansion of the abdominal aorta. Currently, there is no drug treatment to limit abdominal aortic aneurysm growth. The glycocalyx is the outermost layer of the cell surface, mainly composed of glycosaminoglycans and proteoglycans.

OBJECTIVE

The aim of this review was to identify a potential relationship between glycocalyx disruption and abdominal aortic aneurysm pathogenesis.

METHODS

A narrative review of relevant published research was conducted.

RESULTS

Glycocalyx disruption has been reported to enhance vascular permeability, impair immune responses, dysregulate endothelial function, promote extracellular matrix remodeling and modulate mechanotransduction. All these effects are implicated in abdominal aortic aneurysm pathogenesis. Glycocalyx disruption promotes inflammation through exposure of adhesion molecules and release of proinflammatory mediators. Glycocalyx disruption affects how the endothelium responds to shear stress by reducing nitric oxide availabilty and adversely affecting the storage and release of several antioxidants, growth factors, and antithromotic proteins. These changes exacerbate oxidative stress, stimulate vascular smooth muscle cell dysfunction, and promote thrombosis, all effects implicated in abdominal aortic aneurysm pathogenesis. Deficiency of key component of the glycocalyx, such as syndecan-4, were reported to promote aneurysm formation and rupture in the angiotensin-II and calcium chloride induced mouse models of abdominal aortic aneurysm.

CONCLUSION

This review provides a summary of past research which suggests that glycocalyx disruption may play a role in abdominal aortic aneurysm pathogenesis. Further research is needed to establish a causal link between glycocalyx disruption and abdominal aortic aneurysm development.

Vasculoprotective Potential of Baicalein in Angiotensin II-Infused Abdominal Aortic Aneurysms through Inhibiting Inflammation and Oxidative Stress

Aortic wall inflammation, abnormal oxidative stress and progressive degradation of extracellular matrix proteins are the main characteristics of abdominal aortic aneurysms (AAAs). The nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome dysregulation plays a crucial role in aortic damage and disease progression. The first aim of this study was to examine the effect of baicalein (5,6,7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one) on AAA formation in apolipoprotein E-deficient (ApoE-/-) mice. The second aim was to define whether baicalein attenuates aberrant vascular smooth muscle cell (VSMC) proliferation and inflammation in VSMC culture. For male ApoE-/- mice, a clinically relevant AAA model was randomly divided into four groups: saline infusion, baicalein intraperitoneal injection, Angiotensin II (Ang II) infusion and Ang II + baicalein. Twenty-seven days of treatment with baicalein markedly decreased Ang II-infused AAA incidence and aortic diameter, reduced collagen-fiber formation, preserved elastic structure and density and prevented smooth muscle cell contractile protein degradation. Baicalein inhibited rat VSMC proliferation and migration following the stimulation of VSMC cultures with Ang II while blocking the Ang II-inducible cell cycle progression from G0/G1 to the S phase in the synchronized cells. Cal-520 AM staining showed that baicalein decreased cellular calcium in Ang II-induced VSMCs; furthermore, a Western blot assay indicated that baicalein inhibited the expression of PCNA and significantly lowered levels of phospho-Akt and phospho-ERK, along with an increase in baicalein concentration in Ang II-induced VSMCs. Immunofluorescence staining showed that baicalein pretreatment reduced NF-κB nuclear translocation in Ang II-induced VSMCs and furthered the protein expressions of NLRP3 while ASC and caspase-1 were suppressed in a dose-dependent manner. Baicalein pretreatment upregulated Nrf2/HO-1 signaling in Ang II-induced VSMCs. Thus, 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining showed that its reactive oxygen species (ROS) production decreased, along with the baicalein pretreatment. Our overall results indicate that baicalein could have therapeutic potential in preventing aneurysm development.

The Global and Regional Prevalence of Abdominal Aortic Aneurysms: A Systematic Review and Modeling Analysis

OBJECTIVE

To estimate the global and regional prevalence and cases of abdominal aortic aneurysms (AAAs) in 2019 and to evaluate major associated factors.

BACKGROUND

Understanding the global prevalence of AAA is essential for optimizing health services and reducing mortality from reputed AAA.

METHODS

PubMed, MEDLINE, and Embase were searched for articles published until October 11, 2021. Population-based studies that reported AAA prevalence in the general population, defined AAA as an aortic diameter of 30 mm or greater with ultrasonography or computed tomography. A multilevel mixed-effects meta-regression approach was used to establish the relation between age and AAA prevalence for high-demographic sociodemographic index and low-and middle-sociodemographic index countries. Odds ratios of AAA associated factors were pooled using a random-effects method.

RESULTS

We retained 54 articles across 19 countries. The global prevalence of AAA among persons aged 30 to 79 years was 0.92% (95% CI, 0.65-1.30), translating to a total of 35.12 million (95% CI, 24.94-49.80) AAA cases in 2019. Smoking, male sex, family history of AAA, advanced age, hypertension, hypercholesterolemia, obesity, cardiovascular disease, cerebrovascular disease, claudication, peripheral artery disease, pulmonary disease, and renal disease were associated with AAA. In 2019, the Western Pacific region had the highest AAA prevalence at 1.31% (95% CI, 0.94-1.85), whereas the African region had the lowest prevalence at 0.33% (95% CI, 0.23-0.48).

CONCLUSIONS

A substantial proportion of people are affected by AAA. There is a need to optimize epidemiological studies to promptly respond to at-risk and identified cases to improve outcomes.

Abdominal aortic aneurysm presenting to the orthopedic clinic as posterior hip and low back pain

Abdominal aortic aneurysms (AAAs) are typically asymptomatic. When symptomatic, AAA may present as a chief concern of musculoskeletal hip and low back pain. Assessment in the orthopedic clinic should focus on a holistic examination of the patient.

Using red blood cell distribution width to predict death after abdominal aortic aneurysm rupture

BACKGROUND

An abdominal aortic aneurysm is a life-threatening enlargement in the major vessel at the abdomen level. This study investigated the associations between different levels of red blood cell distribution width and all-cause mortality among patients with abdominal aortic aneurysm rupture. It developed predictive models for all-cause mortality risk.

METHODS

This was a retrospective cohort study using 2001 to 2012 MIMIC-III dataset. The study sample included 392 U.S. adults with abdominal aortic aneurysms who were admitted to ICU after the aneurysm rupture. Then we used two single-factor and four multivariable logistic regression models to examine the associations between different levels of red blood cell distribution and all-cause mortality (30 days and 90 days), controlling for demographics, comorbidities, vital signs, and other laboratory measurements. The receiver operator characteristic curves were calculated, and the areas under the curves were recorded.

RESULTS

There were 140 (35.7%) patients with an abdominal aortic aneurysm in the red blood cell distribution width range between 11.7 and 13.8%, 117 (29.8%) patients in the range between 13.9 and 14.9%, and 135 (34.5%) patients in the range between 15.0 and 21.6%. Patients with higher red blood cell distribution width level (> 13.8%) tended to have a higher mortality rate (both 30 days and 90 days), congestive heart failure, renal failure, coagulation disorders, lower hemoglobin, hematocrit, MCV, red blood cell count, higher levels of chloride, creatinine, sodium, and BUN (All P < 0.05). Results of multivariate logistic regression models indicated that patients with higher red blood cell distribution width levels (> 13.8%) had the highest statistically significant odd ratios of 30 days and 90 days of all-cause mortality than lower red blood cell distribution width levels. The area under the RDW curve was lower (P = 0.0009) than that of SAPSII scores.

CONCLUSIONS

Our study found that patients with abdominal aortic aneurysm rupture with a higher blood cell distribution had the highest risk of all-cause mortality. Using the blood cell distribution width level in patients with abdominal aortic aneurysm rupture to predict mortality should be considered in future clinical practice.

The mechanism and therapy of aortic aneurysms

Aortic aneurysm is a chronic aortic disease affected by many factors. Although it is generally asymptomatic, it poses a significant threat to human life due to a high risk of rupture. Because of its strong concealment, it is difficult to diagnose the disease in the early stage. At present, there are no effective drugs for the treatment of aneurysms. Surgical intervention and endovascular treatment are the only therapies. Although current studies have discovered that inflammatory responses as well as the production and activation of various proteases promote aortic aneurysm, the specific mechanisms remain unclear. Researchers are further exploring the pathogenesis of aneurysms to find new targets for diagnosis and treatment. To better understand aortic aneurysm, this review elaborates on the discovery history of aortic aneurysm, main classification and clinical manifestations, related molecular mechanisms, clinical cohort studies and animal models, with the ultimate goal of providing insights into the treatment of this devastating disease. The underlying problem with aneurysm disease is weakening of the aortic wall, leading to progressive dilation. If not treated in time, the aortic aneurysm eventually ruptures. An aortic aneurysm is a local enlargement of an artery caused by a weakening of the aortic wall. The disease is usually asymptomatic but leads to high mortality due to the risk of artery rupture.

Totally percutaneous versus surgical cut-down femoral artery access for elective bifurcated abdominal endovascular aneurysm repair

BACKGROUND

Abdominal aortic aneurysms (AAAs) are a vascular condition with significant risk attached, particularly if they rupture. Therefore, it is critical to identify and repair these as an elective procedure before they rupture and require emergency surgery. Repair has traditionally been an open surgical technique that required a large incision across the abdomen. Endovascular abdominal aortic aneurysm repairs (EVARs) are now a common alternative. In this procedure, the common femoral artery is exposed via a cut-down approach and a graft is introduced to the aneurysm in this way. This Cochrane Review examines a totally percutaneous approach to EVAR. This technique gives a minimally invasive approach to femoral artery access that may reduce groin wound complication rates and improve recovery time. However, the technique may be less applicable in people with, for example, groin scarring or arterial calcification. This is an update of the previous Cochrane Review published in 2017.

OBJECTIVES

To evaluate the benefits and harms of totally percutaneous access compared to cut-down femoral artery access in people undergoing elective bifurcated abdominal endovascular aneurysm repair (EVAR).

SEARCH METHODS

We used standard, extensive Cochrane search methods The latest search was 8 April 2022.

SELECTION CRITERIA

We included randomised controlled trials in people diagnosed with an AAA comparing totally percutaneous versus surgical cut-down access endovascular repair. We considered all device types. We only considered studies investigating elective repairs. We excluded studies reporting emergency surgery for ruptured AAAs and those reporting aorto-uni-iliac repairs.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. short-term mortality, 2. failure of aneurysm exclusion and 3. wound infection. Secondary outcomes were 4. major complications (30-day or in-hospital); 5. medium- to long-term (6 and 12 months) complications and mortality; 6. bleeding complications and haematoma; and 7. operating time, duration of intensive treatment unit (ITU) stay and hospital stay. We used GRADE to assess the certainty of evidence for the seven most clinically relevant primary and secondary outcomes.

MAIN RESULTS

Three studies with 318 participants met the inclusion criteria, 189 undergoing the percutaneous technique and 129 treated by cut-down femoral artery access. One study had a small sample size and did not adequately report the method of randomisation, allocation concealment or preselected outcomes. The other two larger studies had few sources of bias and good methodology; although one study had a high risk of bias in selective reporting. We observed no clear difference in short-term mortality between groups, with only one death occurring overall, in the totally percutaneous group (risk ratio (RR) 1.50, 95% confidence interval (CI) 0.06 to 36.18; 2 studies, 181 participants; low-certainty evidence). One study reported failure of aneurysm exclusion. There was one failure of aneurysm exclusion in the surgical cut-down femoral artery access group (RR 0.17, 95% CI 0.01 to 4.02; 1 study, 151 participants; moderate-certainty evidence). For wound infection, there was no clear difference between groups (RR 0.18, 95% CI 0.01 to 3.59; 3 studies, 318 participants; moderate-certainty evidence). There was no clear difference between percutaneous and cut-down femoral artery access groups in major complications (RR 1.21, 95% CI 0.61 to 2.41; 3 studies, 318 participants; moderate-certainty evidence), bleeding complications (RR 1.02, 95% CI 0.29 to 3.64; 2 studies, 181 participants; moderate-certainty evidence) or haematoma (RR 0.88, 95% CI 0.13 to 6.05; 2 studies, 288 participants). One study reported medium- to long-term complications at six months, with no clear differences between the percutaneous and cut-down femoral artery access groups (RR 0.82, 95% CI 0.25 to 2.65; 1 study, 135 participants; moderate-certainty evidence). We detected differences in operating time, with the percutaneous approach being faster than cut-down femoral artery access (mean difference (MD) -21.13 minutes, 95% CI -41.74 to -0.53 minutes; 3 studies, 318 participants; low-certainty evidence). One study reported the duration of ITU stay and hospital stay, with no clear difference between groups.

AUTHORS' CONCLUSIONS

Skin puncture may make little to no difference to short-term mortality. There is probably little or no difference in failure of aneurysm exclusion (failure to seal the aneurysms), wound infection, major complications within 30 days or while in hospital, medium- to long-term (six months) complications and bleeding complications between the two groups. Compared with exposing the femoral artery, skin puncture may reduce the operating time slightly. We downgraded the certainty of the evidence to moderate and low as a result of imprecision due to the small number of participants, low event rates and wide CIs, and inconsistency due to clinical heterogeneity. As the number of included studies was limited, further research into this technique would be beneficial.

Comparative analysis of thoracic and abdominal aortic aneurysms across the segment and species at the single-cell level

Introduction: Aortic aneurysm is a life-threatening disease resulted from progressive dilatation of the aorta, which can be subdivided into thoracic and abdominal aortic aneurysms. Sustained subcutaneous angiotensin II infusion can induce aortic aneurysms in mice. However, the relevance of using angiotensin II induction model to study aneurysm disease and the degree of commonality between species remain elusive. Methods: We utilized scRNA-seq to infer aortic cell sub-structures and transcriptional profiles in clinical patient TAAs and AAAs, as well as mouse models of corresponding diseases (Ang II induction) and in healthy mouse aorta. Unbiased comparison between mice and humans explored the possible reasonability and utility of mouse Ang II-induced aortic aneurysm as a model for human aortic aneurysm diseases. Meanwhile, we performed comparative analysis of aortic aneurysms between TAA and AAA in both organisms. Results and Discussion: We demonstrated similarities and differences of changes in the components of human and mouse cell types, and our unbiased comparison between mouse and human identified well conserved subpopulations of SMCs and macrophages. Furthermore, the results of our comparative analyses suggested different biological functions and distinct potential pathogenic genes for thoracic and abdominal aortic aneurysms. MIF and SPP1 signaling networks participated in aortic aneurysm in both organisms. This study maps aortic aneurysm and offers opportunities for future researches to investigate the potential of subpopulations or marker genes as therapy targets.

Platelet pannexin-1 channels modulate neutrophil activation and migration but not the progression of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a common disease and highly lethal if untreated. The progressive dilatation of the abdominal aorta is accompanied by degradation and remodeling of the vessel wall due to chronic inflammation. Pannexins represent anion-selective channels and play a crucial role in non-vesicular ATP release to amplify paracrine signaling in cells. Thus, pannexins are involved in many (patho-) physiological processes. Recently, Panx1 channels were identified to be significantly involved in abdominal aortic aneurysm formation through endothelial derived Panx1 regulated inflammation and aortic remodeling. In platelets, Panx1 becomes activated following activation of glycoprotein (GP) VI. Since platelets play a role in cardiovascular diseases including abdominal aortic aneurysm, we analyzed the contribution of platelet Panx1 in the progression of abdominal aortic aneurysm. We detected enhanced Panx1 plasma levels in abdominal aortic aneurysm patients. In experimental abdominal aortic aneurysm using the pancreatic porcine elastase (PPE) mouse model, a major contribution of platelet Panx1 channels in platelet activation, pro-coagulant activity of platelets and platelet-mediated inflammation has been detected. In detail, platelets are important for the migration of neutrophils into the aortic wall induced by direct cell interaction and by activation of endothelial cells. Decreased platelet activation and inflammation did not affect ECM remodeling or wall thickness in platelet-specific Panx1 knock-out mice following PPE surgery. Thus, aortic diameter expansion at different time points after elastase infusion of the aortic wall was unaltered in platelet-specific Panx1 deficient mice suggesting that the modulation of inflammation alone does not affect abdominal aortic aneurysm formation and progression. In conclusion, our data strongly supports the role of platelets in inflammatory responses in abdominal aortic aneurysm via Panx1 channels and adds important knowledge about the significance of platelets in abdominal aortic aneurysm pathology important for the establishment of an anti-platelet therapy for abdominal aortic aneurysm patients.

Abdominal Aortic Thrombus Segmentation in Postoperative Computed Tomography Angiography Images Using Bi-Directional Convolutional Long Short-Term Memory Architecture

Abdominal aortic aneurysm (AAA) is a fatal clinical condition with high mortality. Computed tomography angiography (CTA) imaging is the preferred minimally invasive modality for the long-term postoperative observation of AAA. Accurate segmentation of the thrombus region of interest (ROI) in a postoperative CTA image volume is essential for quantitative assessment and rapid clinical decision making by clinicians. Few investigators have proposed the adoption of convolutional neural networks (CNN). Although these methods demonstrated the potential of CNN architectures by automating the thrombus ROI segmentation, the segmentation performance can be further improved. The existing methods performed the segmentation process independently per 2D image and were incapable of using adjacent images, which could be useful for the robust segmentation of thrombus ROIs. In this work, we propose a thrombus ROI segmentation method to utilize not only the spatial features of a target image, but also the volumetric coherence available from adjacent images. We newly adopted a recurrent neural network, bi-directional convolutional long short-term memory (Bi-CLSTM) architecture, which can learn coherence between a sequence of data. This coherence learning capability can be useful for challenging situations, for example, when the target image exhibits inherent postoperative artifacts and noises, the inclusion of adjacent images would facilitate learning more robust features for thrombus ROI segmentation. We demonstrate the segmentation capability of our Bi-CLSTM-based method with a comparison of the existing 2D-based thrombus ROI segmentation counterpart as well as other established 2D- and 3D-based alternatives. Our comparison is based on a large-scale clinical dataset of 60 patient studies (i.e., 60 CTA image volumes). The results suggest the superior segmentation performance of our Bi-CLSTM-based method by achieving the highest scores of the evaluation metrics, e.g., our Bi-CLSTM results were 0.0331 higher on total overlap and 0.0331 lower on false negative when compared to 2D U-net++ as the second-best.

Gut dysbiosis and bacterial translocation in the aneurysmal wall and blood in patients with abdominal aortic aneurysm

Inflammation plays a part in the development of abdominal aortic aneurysm (AAA), and the gut microbiota affects host inflammation by bacterial translocation. The relationship between abdominal aortic aneurysm and the gut microbiota remains unknown. This study aimed to detect bacterial translocation in the aneurysmal wall and blood of patients with abdominal aortic aneurysm, and to investigate the effect of the gut microbiota on abdominal aortic aneurysm. We investigated 30 patients with abdominal aortic aneurysm from 2017 to 2019. We analysed the aneurysmal wall and blood using highly sensitive reverse transcription-quantitative polymerase chain reaction, and the gut microbiota was investigated using next-generation sequencing. In the 30 patients, bacteria were detected by reverse transcription- quantitative polymerase chain reaction in 19 blood samples (detection rate, 63%) and in 11 aneurysmal wall samples (detection rate, 37%). In the gut microbiota analysis, the Firmicutes/Bacteroidetes ratio was increased. The neutrophil-lymphocyte ratio was higher (2.94 ± 1.77 vs 1.96 ± 0.61, P < 0.05) and the lymphocyte-monocyte ratio was lower (4.02 ± 1.25 vs 5.86 ± 1.38, P < 0.01) in the bacterial carrier group than in the bacterial non-carrier group in blood samples. The volume of intraluminal thrombus was significantly higher in the bacterial carrier group than in the bacterial non-carrier group in aneurysmal wall samples (64.0% vs 34.7%, P < 0.05). We confirmed gut dysbiosis and bacterial translocation to the blood and aneurysmal wall in patients with abdominal aortic aneurysm. There appears to be a relationship between the gut microbiota and abdominal aortic aneurysm.

Harnessing the Electronic Medical Record to Improve the Utilization of Ultrasound Screening for Abdominal Aortic Aneurysms

PURPOSE

The US Preventive Services Task Force recommends one-time ultrasound screening to detect abdominal aortic aneurysms (AAAs) in male smokers. Despite this recommendation, AAA screening is still underutilized. The aim of this study was to determine the effectiveness of an electronic medical record (EMR) automated ordering program in increasing AAA screening at an integrated health care system.

METHODS

This study was a retrospective chart review of patients who underwent ultrasound screening for AAA from January 1, 2016, to December 31, 2021, at a geographically isolated integrated health care system. An automated ordering system was implemented in a stepwise fashion within our EMR beginning in March 2019. The number of ultrasound studies and the incidence of AAA were compared between manual referral and EMR automated ordering periods.

RESULTS

A total of 4,176 patients met the inclusion criteria for this study, among whom 148 aneurysms were identified. There was an increase in the average number of monthly screening ultrasound studies performed during the automated ordering period compared with the manual referral period (105 vs 16.3 studies, P < .001). The incidence of AAA was lower in the automated ordering period compared with the manual referral period (3.2% vs 5.3%, P = .013).

CONCLUSIONS

An EMR automated ordering program can increase the number of screening ultrasound studies performed for AAA, which may help clinicians identify more high-risk aneurysms requiring urgent repair.

Point-of-Care Abdominal Ultrasonography (POCUS) on the Way to the Right and Rapid Diagnosis

Point-of-Care ultrasound (POCUS) is based on target ultrasound that is performed wherever a patient is being treated, and by a non-radiologist directly involved in the patient’s care. It is used either for quick diagnosis or procedural guidance. Abdominal pain is one of the most common complaints in emergency departments, and POCUS can help in the differentiation of patients who need additional diagnostic tests or hospital treatment, which eventually reduces the overall costs of health care. POCUS has high sensitivity and specificity in abdominal pathology, it can be helpful in the evaluation of biliary, intestinal, and urinary tract, and it is especially used in trauma. Additionally, the gold standard for abdominal aortic aneurysm detection, follow up and screening is precisely this diagnostic procedure. Unfortunately, the quality of ultrasound examination can be affected by the experience of the physician performing it and the patient’s body weight. There is no doubt that POCUS is being increasingly recognized, but all motivated physicians should be provided with dedicated tutors and enough time for learning. This would certainly help to implement this diagnostic method as a routine in emergency and critical care departments, and significantly shorten the time until definitive diagnosis.

Association of cardiovascular risk factors and lifestyle behaviors with aortic aneurysm: A Mendelian randomization study

Objective: To examine the causality between hypertension, diabetes, other cardiovascular risk factors, lifestyle behaviors, and the aortic aneurysm among patients of European ancestry.

Methods: We performed two-sample Mendelian randomization (MR) analysis to investigate the causality of 12 modifiable risk factors with aortic aneurysm, including hypertension, body mass index (BMI), waist–hip ratio (WHR), diabetes, tobacco smoking, alcohol and coffee consumption, physical activity, and sleep duration. Genome-wide significant genetic instruments (p < 5 × 10^–8) for risk factors were extracted from European-descent genome-wide association studies, whereas aortic aneurysm genetic instruments were selected from the UK Biobank and FinnGen cohort. The inverse-variance weighted MR was used as the main analysis, and MR-Egger (MRE), weighted median MR, MR pleiotropy residual sum and outlier, and Phenoscanner searching were performed as sensitivity analyses. Furthermore, we calculated MRE intercept to detect pleiotropy and Cochran’s Q statistics to assess heterogeneity and conducted bidirectional MR and MR Steiger tests to exclude the possibility of reverse causality.

Results: We observed significantly higher risks for the aortic aneurysm in hypertension [pooled OR: 4.30 (95% CI 2.84–6.52)], BMI [OR: 1.58 (95% CI 1.37–1.81)], WHR [OR: 1.51 (95% CI 1.21–1.88)], WHR adjusted for BMI (WHRadjBMI) [OR: 1.35 (95% CI 1.12–1.63)], age of smoking initiation [OR: 1.63 (95% CI 1.18–2.26)], and tobacco use (initiation, cessation, and heaviness) [OR: 2.88 (95% CI 1.85–2.26)]. In sensitivity analysis, the causal effects of hypertension, BMI, WHRadjBMI, and tobacco use (initiation, cessation, and heaviness) remained robust.

Conclusion: There was a positive causal relationship between hypertension, BMI, WHR, and WHRadjBMI and aortic aneurysm.

Automatic Detection and Segmentation of Thrombi in Abdominal Aortic Aneurysms Using a Mask Region-Based Convolutional Neural Network with Optimized Loss Functions

The detection and segmentation of thrombi are essential for monitoring the disease progression of abdominal aortic aneurysms (AAAs) and for patient care and management. As they have inherent capabilities to learn complex features, deep convolutional neural networks (CNNs) have been recently introduced to improve thrombus detection and segmentation. However, investigations into the use of CNN methods is in the early stages and most of the existing methods are heavily concerned with the segmentation of thrombi, which only works after they have been detected. In this work, we propose a fully automated method for the whole process of the detection and segmentation of thrombi, which is based on a well-established mask region-based convolutional neural network (Mask R-CNN) framework that we improve with optimized loss functions. The combined use of complete intersection over union (CIoU) and smooth L1 loss was designed for accurate thrombus detection and then thrombus segmentation was improved with a modified focal loss. We evaluated our method against 60 clinically approved patient studies (i.e., computed tomography angiography (CTA) image volume data) by conducting 4-fold cross-validation. The results of comparisons to multiple other state-of-the-art methods suggested the superior performance of our method, which achieved the highest F1 score for thrombus detection (0.9197) and outperformed most metrics for thrombus segmentation.

Cohort Study Examining the Association of Optimal Blood Pressure Control at Entry With Infrarenal Abdominal Aortic Aneurysm Growth

Background and Aim

The benefit of controlling cardiovascular risk factors in slowing the progression of small abdominal aortic aneurysm (AAA) is controversial. This study investigated the association of optimal blood pressure control at entry with the growth of small AAA.

Methods and Results

A total of 1,293 patients with initial AAA diameter <50 mm were followed by a median 5 (inter-quartile range, IQR, 3–7) ultrasound scans for a median of 3.6 years (IQR 1.8, 5.3). Optimal blood pressure control was defined as blood pressure ≤140/90 mmHg at recruitment. The association of optimal blood pressure control at entry with AAA growth was assessed using linear mixed effects models adjusted for established risk factors of AAA growth and factors which were unequally distributed among the blood pressure groups. Optimal blood pressure control at entry was not significantly associated with AAA growth. In the risk factor adjusted model the mean difference in AAA growth between blood pressure groups was 0.04 mm/year (95% CI −0.20, 0.13; p = 0.65). The results were similar in sensitivity analyses excluding outliers or focused on systolic or diastolic blood pressure alone.

Conclusions

This observational study suggests that optimal blood pressure control at entry is not associated with slower AAA growth.

Ultrasonographic Study of the Effects of Essential Hypertension on the Luminal Diameter and Doppler Velocimetric Indices of the Abdominal Aorta in Adults

OBJECTIVE

To investigate the effects of essential hypertension on the luminal diameter (caliber) and Doppler velocimetric indices of the abdominal aorta (AA) in adult patients with systemic hypertension.

MATERIALS AND METHODS

This was a prospective descriptive comparative study of 254 participants (127 with essential hypertension and 127 age/sex-matched controls). Their anthropometric parameters, fasting blood pressure, lipid profile, fasting blood sugar, and triplex sonography of the suprarenal and infrarenal abdominal aorta (Peak systolic velocity, PSV; End-diastolic velocity, EDV; Resistive Index, RI; and luminal diameter) were evaluated.

RESULTS

The mean age of the male subjects was 64.02 ± 10.02 years, while the mean age of the male controls was 63.14 ± 10.52 years (P > 0.05). The mean age of female subjects was 61.23 ± 10.09 years, while the mean age of the female controls was 61.76 ± 10.26 years (P > 0.05). The age group 60 - 69 years had the highest number of subjects and controls. The mean duration of hypertension in the subjects was 12.5 ± 5.2 years. The suprarenal and infrarenal abdominal aortic diameters (AAD) were higher in males than age-matched female counterparts. AAD increased with age mostly in hypertensive male subjects. PSV (in males) and RI (in both sexes) were elevated in hypertensive subjects compared to controls, while EDV (in both sexes) was significantly lower in subjects than controls. Multivariate linear regression showed that age and diastolic blood pressure were significant independent predictors for both suprarenal and infrarenal AADs.

CONCLUSION

Systemic hypertension causes structural and hemodynamic changes in the abdominal aorta which are detectable on triplex sonography.

Experimental aortic aneurysm severity and growth depend on topical elastase concentration and lysyl oxidase inhibition

Abdominal aortic aneurysm (AAA) formation and expansion is highly complex and multifactorial, and the improvement of animal models is an important step to enhance our understanding of AAA pathophysiology. In this study, we explore our ability to influence aneurysm growth in a topical elastase plus β-Aminopropionitrile (BAPN) mouse model by varying elastase concentration and by altering the cross-linking capability of the tissue. To do so, we assess both chronic and acute effects of elastase concentration using volumetric ultrasound. Our results suggest that the applied elastase concentration affects initial elastin degradation, as well as long-term vessel expansion. Additionally, we assessed the effects of BAPN by (1) removing it to restore the cross-linking capability of tissue after aneurysm formation and (2) adding it to animals with stable aneurysms to interrupt cross-linking. These results demonstrate that, even after aneurysm formation, lysyl oxidase inhibition remains necessary for continued expansion. Removing BAPN reduces the aneurysm growth rate to near zero, resulting in a stable aneurysm. In contrast, adding BAPN causes a stable aneurysm to expand. Altogether, these results demonstrate the ability of elastase concentration and BAPN to modulate aneurysm growth rate and severity. The findings open several new areas of investigation in a murine model that mimics many aspects of human AAA.

Appraisal of transthoracic echocardiography for opportunistic screening of abdominal aortic aneurysm

ABSTRACT

Abdominal aortic aneurysm is a life threatening disease. Most of the patients diagnosed incidentally because of the asymptomatic nature of this disease. This study aimed to determine the frequency of abdominal aortic aneurysm and evaluate the value of opportunistic screening during transthoracic echocardiography.A total of 5138 patients referred for echocardiographic evaluation for any reason were screened for abdominal aortic aneurysm between November 2014 to July 2019. The aneurysm was defined as an abdominal aorta with a diameter greater than 30 mm, or segmental dilatation of more than 50% of its size in non-dilated parts.The overall frequency of abdominal aortic aneurysm was 2.2% (n = 109) in the study population. Male sex (P < .001), older age (P < .001), presence of diastolic dysfunction (P = .036), hypertension (P < .001), coronary artery disease (P < .001), and hyperlipidemia (P < .001) were associated with abdominal aortic aneurysm. Patients with aneurysm had significantly increased diameters of the aortic trunk (P < .001) and ascending aorta (P < .001), significantly thicker interventricular septum (P < .001) and posterior wall (P < .001), significantly increased end-diastolic diameter (P < .001) and enlarged left atrium (P < .001), and significantly decreased ejection fraction (P < .001). The mostly met criteria for screening abdominal aortic aneurysm in international guidelines was the age of the patients.Based on the results of this study, screening patients over 60 years of age who undergo a transthoracic echocardiography for any reason would be beneficial to detect an asymptomatic abdominal aortic aneurysm in Turkish population.

Abdominal aortic aneurysms

Vascular surgery is a relatively new surgical sub-speciality in the UK, with treatment of abdominal aortic aneurysms forming a substantial proportion of the emergency and elective caseload. This article summarises the guidance from the National Institute of Health and Care Excellence and the European Society for Vascular Surgery that outlines the epidemiology, diagnosis and management of abdominal aortic aneurysms. This is important for both vascular and non-vascular trainees to understand because of the critical nature of the disease, which can cause catastrophic haemorrhage, limb loss and mortality. However, if discovered in time, abdominal aortic aneurysms are a very treatable condition.

Galectin-3 Modulates Macrophage Activation and Contributes Smooth Muscle Cells Apoptosis in Abdominal Aortic Aneurysm Pathogenesis

Galectin-3 (Gal-3) is a 26-kDa lectin that regulates many aspects of inflammatory cell behavior. We assessed the hypothesis that increased levels of Gal-3 contribute to abdominal aortic aneurysm (AAA) progression by enhancing monocyte chemoattraction through macrophage activation. We analyzed the plasma levels of Gal-3 in 76 patients with AAA (AAA group) and 97 controls (CTL group) as well as in angiotensin II (Ang-II)-infused ApoE knockout mice. Additionally, conditioned media (CM) were used to polarize THP-1 monocyte to M1 macrophages with or without Gal-3 inhibition through small interfering RNA targeted deletion to investigate whether Gal-3 inhibition could attenuate macrophage-induced inflammation and smooth muscle cell (SMC) apoptosis. Our results showed a markedly increased expression of Gal-3 in the plasma and aorta in the AAA patients and experimental mice compared with the CTL group. An in vitro study demonstrated that the M1 cells exhibited increased Gal-3 expression. Gal-3 inhibition markedly decreased the quantity of macrophage-induced inflammatory regulators, including IL-8, TNF-α, and IL-1β, as well as messenger RNA expression and MMP-9 activity. Moreover, Gal-3-deficient CM weakened SMC apoptosis through Fas activation. These findings prove that Gal-3 may contribute to AAA progression by the activation of inflammatory macrophages, thereby promoting SMC apoptosis.

Abdominal aortic aneurysms part one: Epidemiology, presentation and preoperative considerations

An abdominal aortic aneurysm is an irreversible dilatation of the abdominal aorta. The majority of abdominal aortic aneurysms are asymptomatic and identified incidentally while investigating a separate pathology. Others are detected by national screening programmes and some present due to a growth or rupture. Symptomatic or ruptured aneurysms require urgent or emergency repair in patients fit for surgery. Perioperative practitioners should therefore be aware of how patients with abdominal aortic aneurysms present and are investigated, so that they can implement timely management. Guidelines have been recently updated to reflect this. This literature review discusses these recommendations and explores the evidence upon which they are based. The aim of this article is to highlight the important preoperative principles that need to be considered in cases of abdominal aortic aneurysm.

Partners' experiences of living with men who have screening-detected abdominal aortic aneurysms: A qualitative descriptive study

AIM

To describe partners' experiences of living with men with a screening-detected abdominal aortic aneurysm (AAA).

BACKGROUND

Diagnosis of a chronic life-threatening disease affects the patients' as well as their partners' lives in different aspects. AAA, with rupture as the major consequence, is a life-threatening disease that can affect the whole family. Screening programmes for AAA have been introduced in several countries to reduce the mortality rate. Although the awareness of having an AAA influences the individuals' quality of life and well-being, it is still unclear how it affects their partners.

DESIGN

Qualitative descriptive design.

METHODS

Twenty-one partners of men with AAA were purposely selected to participate in individual semi-structured interviews between August 2017-February 2018 in Sweden. Data were transcribed and imported into NVivo-12^® . The data were analysed using qualitative content analysis. The study conforms to the COREQ checklist.

RESULTS

Three categories were identified: (a) experiencing the unexpected; (b) being reminded of fragility; and (c) balancing a changing relationship. The partners had a positive attitude towards the screening process and were pleased that their husbands were under surveillance. Nevertheless, at the same time, the diagnosis caused worries and questions. The AAA diagnosis was constantly in the minds of the partners, which sometimes affected and limited daily activities. Furthermore, ambivalent feelings towards surgical treatment were described. The partners tried to support their men and encouraged them to achieve a healthy lifestyle.

CONCLUSION

The partners' well-being and daily lives were impacted by the awareness of the screening-detected AAA. Different degrees of worry were the most common reaction and were pervasive in all three categories.

RELEVANCE FOR CLINICAL PRACTICE

The result highlights the need to review routines or develop new strategies to include the partners in the process of screening and offer supplementary support and information.

Extracellular matrix, regional heterogeneity of the aorta, and aortic aneurysm

Aortic aneurysm is an asymptomatic disease with dire outcomes if undiagnosed. Aortic aneurysm rupture is a significant cause of death worldwide. To date, surgical repair or endovascular repair (EVAR) is the only effective treatment for aortic aneurysm, as no pharmacological treatment has been found effective. Aortic aneurysm, a focal dilation of the aorta, can be formed in the thoracic (TAA) or the abdominal (AAA) region; however, our understanding as to what determines the site of aneurysm formation remains quite limited. The extracellular matrix (ECM) is the noncellular component of the aortic wall, that in addition to providing structural support, regulates bioavailability of an array of growth factors and cytokines, thereby influencing cell function and behavior that ultimately determine physiological or pathological remodeling of the aortic wall. Here, we provide an overview of the ECM proteins that have been reported to be involved in aortic aneurysm formation in humans or animal models, and the experimental models for TAA and AAA and the link to ECM manipulations. We also provide a comparative analysis, where data available, between TAA and AAA, and how aberrant ECM proteolysis versus disrupted synthesis may determine the site of aneurysm formation.

A review of aneurysm formation, swelling in blood vessel, in the aorta, examines distinctions between two forms of the condition and the role of proteins in the extracellular matrix which surrounds cells of the arterial wall. Rupture of aneurysms in the aorta, the body’s main artery, is a major cause of death. Researchers led by Zamaneh Kassiri at the University of Alberta, Edmonton, Canada, emphasize that aneurysms in the thoracic and abdominal regions of the aorta are distinct conditions with crucial differences in their causes. Disrupted production and assembly of the extracellular matrix and its proteins may underlie thoracic aneurysm formation. Factors triggering the degradation of extracellular matrix proteins may be more significant in abdominal aneurysms. Understanding the differing molecular mechanisms involved could help address the current lack of effective drug treatments for these dangerous conditions.

Screening for Abdominal Aortic Aneurysm: US Preventive Services Task Force Recommendation Statement

IMPORTANCE

An abdominal aortic aneurysm (AAA) is typically defined as aortic enlargement with a diameter of 3.0 cm or larger. The prevalence of AAA has declined over the past 2 decades among screened men 65 years or older in various European countries. The current prevalence of AAA in the United States is unclear because of the low uptake of screening. Most AAAs are asymptomatic until they rupture. Although the risk for rupture varies greatly by aneurysm size, the associated risk for death with rupture is as high as 81%.

OBJECTIVE

To update its 2014 recommendation, the USPSTF commissioned a review of the evidence on the effectiveness of 1-time and repeated screening for AAA, the associated harms of screening, and the benefits and harms of available treatments for small AAAs (3.0-5.4 cm in diameter) identified through screening.

POPULATION

This recommendation applies to asymptomatic adults 50 years or older. However, the randomized trial evidence focuses almost entirely on men aged 65 to 75 years.

EVIDENCE ASSESSMENT

Based on a review of the evidence, the USPSTF concludes with moderate certainty that screening for AAA in men aged 65 to 75 years who have ever smoked is of moderate net benefit. The USPSTF concludes with moderate certainty that screening for AAA in men aged 65 to 75 years who have never smoked is of small net benefit. The USPSTF concludes that the evidence is insufficient to determine the net benefit of screening for AAA in women aged 65 to 75 years who have ever smoked or have a family history of AAA. The USPSTF concludes with moderate certainty that the harms of screening for AAA in women aged 65 to 75 years who have never smoked and have no family history of AAA outweigh the benefits.

RECOMMENDATIONS

The USPSTF recommends 1-time screening for AAA with ultrasonography in men aged 65 to 75 years who have ever smoked. (B recommendation) The USPSTF recommends that clinicians selectively offer screening for AAA with ultrasonography in men aged 65 to 75 years who have never smoked rather than routinely screening all men in this group. (C recommendation) The USPSTF recommends against routine screening for AAA with ultrasonography in women who have never smoked and have no family history of AAA. (D recommendation) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for AAA with ultrasonography in women aged 65 to 75 years who have ever smoked or have a family history of AAA. (I statement).

Primary Care Screening for Abdominal Aortic Aneurysm: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Ruptured abdominal aortic aneurysms (AAAs) have mortality estimated at 81%.

OBJECTIVE

To systematically review the evidence on benefits and harms of AAA screening and small aneurysm treatment to inform the US Preventive Services Task Force.

DATA SOURCES

MEDLINE, PubMed (publisher supplied only), Database of Abstracts of Reviews of Effects, and Cochrane Central Register of Controlled Trials for relevant English-language studies published through September 2018. Surveillance continued through July 2019.

STUDY SELECTION

Trials of AAA screening benefits and harms; trials and cohort studies of small (3.0-5.4 cm) AAA treatment benefits and harms.

DATA EXTRACTION AND SYNTHESIS

Two investigators independently reviewed abstracts and full-text articles and extracted data. The Peto method was used to pool odds ratios (ORs) for AAA-related mortality, rupture, and operations; the DerSimonian and Laird random-effects model was used to pool calculated risk ratios for all-cause mortality.

MAIN OUTCOMES AND MEASURES

AAA and all-cause mortality; AAA rupture; treatment complications.

RESULTS

Fifty studies (N = 323 279) met inclusion criteria. Meta-analysis of population-based randomized clinical trials (RCTs) estimated that a screening invitation to men 65 years or older was associated with a reduction in AAA-related mortality over 12 to 15 years (OR, 0.65 [95% CI, 0.57-0.74]; 4 RCTs [n = 124 926]), AAA-related ruptures over 12 to 15 years (OR, 0.62 [95% CI, 0.55-0.70]; 4 RCTs [n = 124 929]), and emergency surgical procedures over 4 to 15 years (OR, 0.57 [95% CI, 0.48-0.68]; 5 RCTS [n = 175 085]). In contrast, no significant association with all-cause mortality benefit was seen at 12- to 15-year follow-up (relative risk, 0.99 [95% CI 0.98-1.00]; 4 RCTs [n = 124 929]). One-time screening was associated with significantly more procedures over 4 to 15 years in the invited group compared with the control group (OR, 1.44 [95% CI, 1.34-1.55]; 5 RCTs [n = 175 085]). Four trials (n = 3314) of small aneurysm surgical treatment demonstrated no significant difference in AAA-related mortality or all-cause mortality compared with surveillance over 1.7 to 12 years. These 4 early surgery trials showed a substantial increase in procedures in the early surgery group. For small aneurysm treatment, registry data (3 studies [n = 14 424]) showed that women had higher surgical complications and postoperative mortality compared with men.

CONCLUSIONS AND RELEVANCE

One-time AAA screening in men 65 years or older was associated with decreased AAA-related mortality and rupture rates but was not associated with all-cause mortality benefit. Higher rates of elective surgery but no long-term differences in quality of life resulted from screening.

Life is about so much more: Patients' experiences of health, well-being, and recovery after operation of abdominal aortic aneurysm with open and endovascular treatment-A prospective study

Different surgical treatments for abdominal aortic aneurysm can lead to different perceptions of health and well-being. The aim of this study was to describe patients' well-being, sense of coherence (SOC), and experiences of surgery after open and endovascular treatment one month and one and 2 years after the procedure. Seventy six patients participated (40 open repair; 36 endovascular aneurysm repair). The study was conducted using the SOC questionnaire, and specific questions about patients' experiences of the surgical treatment and well-being. After 2 years, no patient regretted the operation or considered it to be the most difficult experience they had ever had. Twenty percent of the patients were worried about complications one month after the operation. Both groups experienced difficulty in returning to normal activity after surgery at one month. At one and 2 years after the surgery, patients in both groups stated that it was other things in life that affected their well-being. The endovascular aneurysm repair group reported a significant decrease in SOC from baseline until one year (P = .012) and 2 years (P = .033). The open repair group reported a significant decrease after one year (0.033). The operation did not affect patients' way of thinking about the disease. Patients in both groups stated that it was other circumstances in life that affected their well-being one and 2 years after the treatment, which could indicate that long-term follow-up would not be necessary from a patient perspective. The operation affects patients' well-being a short time after the operation.

Inferior Mid-term Durability with Comparable Survival for Younger Patients Undergoing Elective Endovascular Infrarenal versus Open Abdominal Aortic Aneurysm Repair

BACKGROUND

The durability of endovascular aneurysm repair (EVAR) when compared to open surgical repair (OSR) in younger patients for elective, infrarenal abdominal aortic aneurysms (AAA) remains unclear due to limited follow-up.

METHODS

We identified all patients <70 years of age who underwent elective, de novo EVAR or OSR for infrarenal AAA from 2003 to 2013 in a multihospital, single institution. Baseline patient clinical and aneurysmal characteristics were adjusted for using multivariable Cox proportional hazards models and negative binomial regression.

RESULTS

We identified 253 patients: 204 underwent EVAR (80.6%) and 49 OSR (19.4%). Baseline demographics and comorbidities were similar across groups. There were no deaths in the immediate perioperative period. The rate of new arrhythmia (EVAR: 1.0%, OSR: 10.2%; P = 0.004), median hospital length of stay (EVAR: 1 day, OSR: 5 days; P < 0.001), and discharge to a facility (EVAR: 2.9%, OSR: 12.2%; P = 0.016) were significantly increased for OSR. In both groups, median follow-up time was 4.5 years, in which survival did not differ between groups. The hazard of composite of freedom from death and any reinterventions (hazard ratio [HR] 4.3, P = 0.009), freedom from any reintervention (relative risk [RR] 4.08, P = 0.030), and freedom from any endovascular reintervention (RR 4.83, P = 0.038) were each higher for OSR when compared to EVAR. EVAR of the standard instruction for use (IFU) for neck length was more likely to die or undergo a reintervention (HR 4.90, P = 0.001).

CONCLUSIONS

Our retrospective review of younger patients undergoing elective AAA repair demonstrated no significant differences in perioperative mortality or survival over time between EVAR and OSR. EVAR required more total reinterventions and endovascular reintervention when compared to OSR.

Impaired smooth muscle cell contractility as a novel concept of abdominal aortic aneurysm pathophysiology

Ruptured abdominal aortic aneurysms (AAA) are associated with overall mortality rates up to 90%. Despite extensive research, mechanisms leading to AAA formation and advancement are still poorly understood. Smooth muscle cells (SMC) are predominant in the aortic medial layer and maintain the wall structure. Apoptosis of SMC is a well-known phenomenon in the pathophysiology of AAA. However, remaining SMC function is less extensively studied. The aim of this study is to assess the in vitro contractility of human AAA and non-pathologic aortic SMC. Biopsies were perioperatively harvested from AAA patients (n = 21) and controls (n = 6) and clinical data were collected. Contractility was measured using Electric Cell-substrate Impedance Sensing (ECIS) upon ionomycin stimulation. Additionally, SMC of 23% (5 out of 21) of AAA patients showed impaired maximum contraction compared to controls. Also, SMC from patients who underwent open repair after earlier endovascular repair and SMC from current smokers showed decreased maximum contraction vs. controls (p = 0.050 and p = 0.030, respectively). Our application of ECIS can be used to study contractility in other vascular diseases. Finally, our study provides with first proof that impaired SMC contractility might play a role in AAA pathophysiology.

Blood pressure, hypertension and the risk of abdominal aortic aneurysms: a systematic review and meta-analysis of cohort studies

Abdominal aortic aneurysms (AAA) are fatal in 80% of the cases when ruptured. Hypertension has been considered a potential risk factor for AAA; but the findings from prospective cohort studies have not been entirely consistent, nor have they been summarised in a comprehensive meta-analysis. Our aim was to conduct a systematic review and meta-analysis of cohort studies of the association between blood pressure, hypertension and AAA to clarify the strength and shape of these associations. We searched PubMed and Embase databases for relevant cohort studies up to April 30th, 2018. Random-effects models were used to calculate summary relative risks (RRs) and 95% confidence intervals (CIs). The meta-analysis included 21 cohort studies (20 publications) with data on 28,162 cases and 5,440,588 participants. The findings indicate that the RR of AAA in hypertensive patients is 1.66 times (95% CI: 1.49–1.85, I² = 79.3%, n = 13) that of non-hypertensive patients. In addition, there was a 14% (95% CI: 6–23%, I² = 30.5%, n = 6) and a 28% (95% CI: 12–46%, I² = 80.1%, n = 6) increase in the RR of AAA for every 20 mmHg and 10 mmHg increase in systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively. The analysis of DBP showed evidence of a strong and highly significant nonlinear dose–response relationship (p < 0.001) with a steeper association from 80 mmHg and above. This meta-analysis suggests that hypertension increases the risk of developing AAA by 66%. Further studies are needed to clarify the underlying mechanism explaining the much stronger association between DBP and AAA than for SBP.

Coronary Artery Disease as a Relevant Risk Factor in Screening of Abdominal Aortic Ectasia and Aneurysm

BACKGROUND

The aim of this study was to investigate the prevalence of abdominal aortic aneurysm (AAA) and abdominal aortic ectasia (AAE) in coronary artery disease (CAD) patients in a multicenter setting to obtain significant data to establish an AAA screening program in our departments.

METHODS

Between January and September 2016, 500 patients with suspected or diagnosed CAD planned for coronary angiography or coronary artery bypass graft (CABG) underwent a sonographic examination of the infrarenal abdominal aorta to diagnose AAA or AAE. We calculated the prevalence of AAA and AAE in patients diagnosed of CAD and investigated factors potentially associated with the occurrence of AAA.

RESULTS

The overall prevalence in all grades of CAD for AAE was 35.1% and for AAA 5.4%. In patients with three-vessel CAD, the prevalence of AAE was 34% and of AAA 6.8%. Significant correlation was found between the three-vessel CAD and AAA (p = 0.039). The logistic regression analysis showed significant correlation between AAA and age > 65 years (p = 0.05). The multivariate analysis of risk factors and CAD revealed significant correlations between one-vessel CAD and arterial hypertension (AH) (p = 0.004) and age > 65 years (p = 0.001) as well as between three-vessel CAD and AH (p = 0.01), peripheral artery disease (p = 0.01), and age > 65 years (p = 0.03).

CONCLUSION

Our results confirm, that in comparison to other data, the prevalence of AAA in patients with CAD is high. Thus, it is recommended to include patients with CAD, especially elderly patients with three-vessel CAD, in future AAA screening programs.

[Prevalence and risk factors of sub-renal abdominal aortic aneurysm in an Algerian population aged over 60]

INTRODUCTION

The prevalence of abdominal aortic aneurysm (AAA) in the general population in our country is not known, our aim was to evaluate it in patients over 60 years of age, to specify the risk factors and to evaluate the extension of aneurysmal disease and multisite subclinical atherosclerosis.

METHODS

Descriptive, transversal, study collecting the data of a systematic ultrasound screening of sub-renal AAA in subjects receiving care in two Algerian hospital structures. Epidemiological data, AAA risk factors, cardiovascular disease risk factors (CVD RF) and the personal history (cardiovascular diseases, chronic obstructive pulmonary disease) and family history of AAA were collected during the screening. An abdominal echography was performed in all patients. A biological and morphological assessment was carried out for AAA cases detected. Multivariate logistic regression analysis was used to study the factors associated with AAA.

RESULTS

Systematic screening for 600 patients revealed an overall AAA prevalence of 2.2% (n=13). In multivariate analysis a positive association with AAA was observed with active smoking, its duration in years and its intensity in year-packages; with hypertension, dyslipidemia and a history of cardiovascular events. While a negative association was observed with a smoking cessation of more than 20 years, type 2 diabetes and android obesity. The study of detected AAA cases found five cases of aneurysm isolated from the primary iliac artery but no popliteal and/or femoral aneurysm. The carotids were atheromatous in more than 80% of cases and the arteries of the lower limbs in more than one-third of cases.

CONCLUSION

The prevalence of AAA in our population (2.2%) corresponds to the prevalence reported recently in Europe, but it would have been higher if the screening had targeted males and smokers. The factors associated with AAA in our patients are similar to those described in the literature.

Pathophisiology of abdominal aortic aneurysm: biomarkers and novel therapeutic targets

Abdominal aortic aneurysm (AAA) is a vascular pathology with a high rate of morbidity and mortality and a prevalence that, in men over 65 years, can reach around 8%. In this disease, usually asymptomatic, there is a progressive dilatation of the vascular wall that can lead to its rupture, a fatal phenomenon in more than 80% of cases. The treatment of patients with asymptomatic aneurysms is limited to periodic monitoring with imaging tests, control of cardiovascular risk factors and treatment with statins and antiplatelet therapy. There is no effective pharmacological treatment capable of limiting AAA progression or avoiding their rupture. At present, the aortic diameter is the only marker of risk of rupture and determines the need for surgical repair when it reaches values greater than 5.5cm. This review addresses the main aspects related to epidemiology, risk factors, diagnosis and clinical management of AAA, exposes the difficulties to have good biomarkers of this pathology and describes the strategies for the identification of new therapeutic targets and biomarkers in AAA.

Oral hygiene and periodontal conditions in the Chinese patients with aortic aneurysm

Background

This cross-sectional study aims to evaluate the association of periodontal conditions and oral hygiene habits in the Chinese patients with an aortic aneurysm (AA).

Methods

A questionnaire and periodontal examinations were carried out in the AA patients and non-AA volunteers recruited from the Center for Cardiac Surgery, Beijing Anzhen Hospital, Capital Medical University between August 2011 and June 2016. General information (e.g., height and weight), history of systemic diseases, and oral hygiene habits (e.g., brushing methods and regular oral examinations) were collected in the self-reported survey. Periodontal examinations, such as plaque index and bleeding index, were conducted in all the subjects. The correlation between periodontal indices and AA was further explored using univariate and multivariate analyses.

Results

Our analyses revealed that 87.6% of AA patients have chronic periodontitis, which is significantly higher than that of the non-AA patients (55.8%). In addition, AA patients demonstrated more severe periodontal damages with 69.3% moderate and severe periodontitis, compared to only 16.0% in the non-AA group. Using AA as the dependent variable and all the potential risk factors as covariates (e.g., gender, age, smoking, obesity, diabetes, hypertension, and hyperlipidemia), a logistic regression analysis was performed to show clinical attachment loss (CAL) being an independent risk factor for AA (OR = 2.309, 95% CI: 1.623–3.284, p = 0.000). In comparison with the non-AA patients, more AA patients have poor oral hygiene habits and don’t have regular dental appointments for supra-gingival cleaning.

Conclusion

Poor periodontal condition and dental hygiene were identified in the AA patients, suggesting that periodontitis-induced CAL may play a role in AA disease mechanisms.

Abdominal Aortic Aneurysm: Evolving Controversies and Uncertainties

Abdominal aortic aneurysm (AAA) is defined as a permanent dilatation of the abdominal aorta that exceeds 3 cm. Most AAAs arise in the portion of abdominal aorta distal to the renal arteries and are defined as infrarenal. Most AAAs are totally asymptomatic until catastrophic rupture. The strongest predictor of AAA rupture is the diameter. Surgery is indicated to prevent rupture when the risk of rupture exceeds the risk of surgery. In this review, we aim to analyze this disease comprehensively, starting from an epidemiological perspective, exploring etiology and pathophysiology, and concluding with surgical controversies. We will pursue these goals by addressing eight specific questions regarding AAA: (1) Is the incidence of AAA increasing? (2) Are ultrasound screening programs for AAA effective? (3) What causes AAA: Genes versus environment? (4) Animal models: Are they really relevant? (5) What pathophysiology leads to AAA? (6) Indications for AAA surgery: Are surgeons over-eager to operate? (7) Elective AAA repair: Open or endovascular? (8) Emergency AAA repair: Open or endovascular?

Inhibition of miR-155 attenuates abdominal aortic aneurysm in mice by regulating macrophage-mediated inflammation

The aim of the present study was to identify abdominal aortic aneurysms (AAA)-associated miR-155 contributing to AAA pathology by regulating macrophage-mediated inflammation. Angiotensin II (AngII)-infused apolipoprotein E-deficient (ApoE-/-) mice and THP-1 cells model of miR-155 overexpression and deficiency were used in the experiments. The expression of miR-155 was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cytokines were evaluated using enzyme-linked immunoabsorbent assay (ELISA). Western blotting was used to measure the levels of MMP-2, MMP-9, iNOS, and monocyte chemoattractant protein (MCP)-1 proteins. Immunostaining and transwell were used to determine CD68, elastic collagen, proliferation, and migration of vascular smooth muscle cells (VSMCs). The results showed that miR-155 and cytokines were up-regulated in AAA patients or ApoE-/- mice. Overexpression of miR-155 enhanced MMP-2, MMP-9, iNOS, and MCP-1 levels, and stimulated the proliferation and migration of VSMCs. Meanwhile, inhibition of miR-155 had the opposite effect. In addition, histology demonstrated accumulation of CD68 and elastic collagen-positive areas significantly decreased in miR-155 antagomir injection group. In conclusion, the results of the present study suggest that inhibiting miR-155 is crucial to prevent the development of AAA by regulating macrophage inflammation.

Sex-dependent outcomes following elective endovascular aortic repair

BACKGROUND

Evidence has shown that women derive less benefit from endovascular aortic repair (EVAR) in large part due to more challenging aortoiliac anatomy. This study sought to examine whether sex-dependent outcomes exist following elective EVAR cases.

METHODS

An institutional retrospective review was performed on patients who underwent elective EVAR procedures between 2008 and 2014. Outcome data collected included procedural and hospital morbidity, mortality, and overall EVAR durability based on the incidence of unplanned graft-related secondary interventions (SIs) (e.g., open conversion, proximal or distal extensions, and coil embolizations).

RESULTS

One hundred eighty-one patients (150 men, 31 women) met the study inclusion criteria. Median follow-up was 40.3 mo. Women had more challenging anatomy compared to men including smaller overall iliac diameters (6.8 mm versus 8.0 mm, P < 0.001) and more severe iliac angulation (77% moderate to severe versus 44%, P < 0.001). Women had increased risk of postoperative complications compared to men (41.9% versus 11.3%, P = 0.003). There was no perioperative mortality in our series of elective EVAR cases. Median 5-y survival following EVAR was 64.4% for men and 76.3% for women (P = 0.599). Late SI rates following EVAR was 10.5% with 16 (10.7%) men and 3 (9.7%) women needing interventions (P = 0.870). Overall durability of EVAR extrapolated as time to SIs was 91% at 2 y and 85% at 5 y. Factors predisposing SIs were iliac tortuosity (P = 0.046), aortic neck angle (P = 0.022), and endoleak at the follow-up (P = 0.030).

CONCLUSIONS

In this study, immediate outcomes following EVAR were different between men and women, with women having increased rates of postoperative complications. Mortality and overall long-term durability of EVAR, however, were the same between sexes despite anatomical differences. EVAR durability was significantly dependent on the severity of iliac tortuosity, aortic neck angulation, and presence of endoleak at the follow-up.

An evaluation of the effect of an angiotensin-converting enzyme inhibitor on the growth rate of small abdominal aortic aneurysms: a randomised placebo-controlled trial (AARDVARK)

BACKGROUND

Although data are inconsistent, angiotensin-converting enzyme inhibitors (ACE-Is) have been associated with a reduced incidence of abdominal aortic aneurysm (AAA) rupture in analysis of administrative databases.

OBJECTIVES

(1) To investigate whether or not the ACE-I perindopril (Coversyl arginine, Servier) reduces small AAA growth rate and (2) to evaluate blood pressure (BP)-independent effects of perindopril on small AAA growth and to compare the repeatability of measurement of internal and external aneurysm diameters.

DESIGN

A three-arm, multicentre, single-blind, randomised placebo-controlled trial.

SETTING

Fourteen hospitals in England.

PARTICIPANTS

Men or women aged ≥ 55 years with an AAA of 3.0-5.4 cm in diameter by internal or external measurement according to ultrasonography and who met the trial eligibility criteria.

INTERVENTIONS

Patients were randomised to receive 10 mg of perindopril arginine daily, 5 mg of the calcium channel blocker amlodipine daily or placebo daily.

MAIN OUTCOME MEASURES

The primary outcome was AAA diameter growth using external measurements in the longitudinal plane, which in-trial studies suggested was the preferred measure. Secondary outcome measures included AAA rupture, AAA repair, modelling of the time taken for the AAA to reach the threshold for intervention (5.5 cm) or referral for surgery, tolerance of study medication (measured by compliance, adverse events and quality of life) and a comparison of the repeatability of measures of internal and external AAA diameter. Patients were followed up every 3-6 months over 2 years.

RESULTS

In total, 227 patients were recruited and randomised into the three groups, which were generally well matched at baseline. Multilevel modelling was used to determine the maximum likelihood estimates for AAA diameter growth. No significant differences in the estimates of annual growth were apparent [1.68 (standard error 0.02) mm, 1.77 (0.02) mm and 1.81 (0.02) mm in the placebo, perindopril and amlodipine groups, respectively]. Similarly, no significant differences in the slopes of modelled growth over time were apparent between perindopril and placebo (p = 0.78) or between perindopril and amlodipine (p = 0.89). The results were essentially unaffected by adjustment for potential confounders. Compliance, measured by pill counts, was good throughout (> 80% at all visit time points). There were no significant in-trial safety concerns. Six patients withdrew because of adverse events attributed to the study medications (n = 2 perindopril, n = 4 amlodipine). No patients ruptured their AAA and 27 underwent elective surgery during the trial (n = 9 placebo, n = 10 perindopril, n = 8 amlodipine).

CONCLUSIONS

We were unable to demonstrate a significant impact of perindopril compared with placebo or amlodipine on small AAA growth over a 2-year period. Furthermore, there were no differences in the times to reach a diameter of 5.5 cm or undergo surgery among the three groups. Perindopril and amlodipine were well tolerated by this population. External AAA measurements were found to be more repeatable than internal measurements. The observed AAA growth measurement variability was greater than that expected pre trial. This, combined with slower than expected mean growth rates, resulted in our having limited power to detect small differences between growth rates and hence this adds uncertainty to the interpretation of the results. Several further analyses are planned including a multivariate analysis of determinants of AAA growth, an evaluation of the possible differential effect of perindopril on fast AAA growth and an investigation into the roles of central BP and BP variability on AAA growth.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN51383267.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 59. See the NIHR Journals Library website for further project information. The NIHR Biomedical Research Centre based at Imperial College NHS Trust supported the trial. Servier provided perindopril at no charge.

Muse Cells and Aortic Aneurysm

The aorta is a well-organized, multilayered structure comprising several cell types, namely, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and fibroblasts, as well as an extracellular matrix (ECM), which includes elastic and collagen fibers. Aortic aneurysms (AAs) are defined as progressive enlargements of the aorta that carries an incremental risk of rupture as the diameter increases over time. The destruction of the aortic wall tissue is triggered by atherosclerosis, inflammation, and oxidative stress, leading to the activation of matrix metalloproteinases (MMPs), and inflammatory cytokines and chemokines, resulting in the loss of the structural back bone of VSMCs, ECM, and ECs. To date, cell-based therapy has been applied to animal models using several types of cells, such as VSMCs, ECs, and mesenchymal stem cells (MSCs). Although these cells indeed deliver beneficial outcomes for AAs, particularly by paracrine and immunomodulatory effects, the attenuation of aneurysmal dilation with a robust tissue repair is insufficient. Meanwhile, multilineage-differentiating stress-enduring (Muse) cells are known to be endogenous non-tumorigenic pluripotent-like stem cells that are included as several percent of MSCs. Since Muse cells are pluripotent-like, they have the ability to differentiate into cells representative of all three germ layers from a single cell and to self-renew. Moreover, Muse cells are able to home to the site of damage following simple intravenous injection and repair the tissue by replenishing new functional cells through spontaneous differentiation into tissue-compatible cells. Given these unique properties, Muse cells are expected to provide an efficient therapeutic efficacy for AA by simple intravenous injection. In this chapter, we summarize several studies on Muse cell therapy for AA including our recent data, in comparison with other kinds of cell therapies.

The UK EndoVascular Aneurysm Repair (EVAR) randomised controlled trials: long-term follow-up and cost-effectiveness analysis

BACKGROUND

Short-term survival benefits of endovascular aneurysm repair (EVAR) compared with open repair (OR) of intact abdominal aortic aneurysms have been shown in randomised trials, but this early survival benefit is soon lost. Survival benefit of EVAR was unclear at follow-up to 10 years.

OBJECTIVE

To assess the long-term efficacy of EVAR against OR in patients deemed fit and suitable for both procedures (EVAR trial 1; EVAR-1); and against no intervention in patients unfit for OR (EVAR trial 2; EVAR-2). To appraise the long-term significance of type II endoleak and define criteria for intervention.

DESIGN

Two national, multicentre randomised controlled trials: EVAR-1 and EVAR-2.

SETTING

Patients were recruited from 37 hospitals in the UK between 1 September 1999 and 31 August 2004.

PARTICIPANTS

Men and women aged ≥ 60 years with an aneurysm of ≥ 5.5 cm (as identified by computed tomography scanning), anatomically suitable and fit for OR were randomly assigned 1 : 1 to either EVAR (n = 626) or OR (n = 626) in EVAR-1 using computer-generated sequences at the trial hub. Patients considered unfit were randomly assigned to EVAR (n = 197) or no intervention (n = 207) in EVAR-2. There was no blinding.

INTERVENTIONS

EVAR, OR or no intervention.

MAIN OUTCOME MEASURES

The primary end points were total and aneurysm-related mortality until mid-2015 for both trials. Secondary outcomes for EVAR-1 were reinterventions, costs and cost-effectiveness.

RESULTS

In EVAR-1, over a mean of 12.7 years (standard deviation 1.5 years; maximum 15.8 years), we recorded 9.3 deaths per 100 person-years in the EVAR group and 8.9 deaths per 100 person-years in the OR group [adjusted hazard ratio (HR) 1.11, 95% confidence interval (CI) 0.97 to 1.27; p = 0.14]. At 0-6 months after randomisation, patients in the EVAR group had a lower mortality (adjusted HR 0.61, 95% CI 0.37 to 1.02 for total mortality; HR 0.47, 95% CI 0.23 to 0.93 for aneurysm-related mortality; p = 0.031), but beyond 8 years of follow-up patients in the OR group had a significantly lower mortality (adjusted HR 1.25, 95% CI 1.00 to 1.56, p = 0.048 for total mortality; HR 5.82, 95% CI 1.64 to 20.65, p = 0.0064 for aneurysm-related mortality). The increased aneurysm-related mortality in the EVAR group after 8 years was mainly attributable to secondary aneurysm sac rupture, with increased cancer mortality also observed in the EVAR group. Overall, aneurysm reintervention rates were higher in the EVAR group than in the OR group, 4.1 and 1.7 per 100 person-years, respectively (p < 0.001), with reinterventions occurring throughout follow-up. The mean difference in costs over 14 years was £3798 (95% CI £2338 to £5258). Economic modelling based on the outcomes of the EVAR-1 trial showed that the cost per quality-adjusted life-year gained over the patient's lifetime exceeds conventional thresholds used in the UK. In EVAR-2, patients died at the same rate in both groups, but there was suggestion of lower aneurysm mortality in those who actually underwent EVAR. Type II endoleak itself is not associated with a higher rate of mortality.

LIMITATIONS

Devices used were implanted between 1999 and 2004. Newer devices might have better results. Later follow-up imaging declined, particularly for OR patients. Methodology to capture reinterventions changed mainly to record linkage through the Hospital Episode Statistics administrative data set from 2009.

CONCLUSIONS

EVAR has an early survival benefit but an inferior late survival benefit compared with OR, which needs to be addressed by lifelong surveillance of EVAR and reintervention if necessary. EVAR does not prolong life in patients unfit for OR. Type II endoleak alone is relatively benign.

FUTURE WORK

To find easier ways to monitor sac expansion to trigger timely reintervention.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN55703451.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and the results will be published in full in Health Technology Assessment; Vol. 22, No. 5. See the NIHR Journals Library website for further project information.