Traditional and novel risk factors for clinically diagnosed abdominal aortic aneurysm: the Kaiser multiphasic health checkup cohort study

Ganglioside GM3 Protects Against Abdominal Aortic Aneurysm by Suppressing Ferroptosis

BACKGROUND

Abdominal aortic aneurysm (AAA) is a potentially life-threatening vascular condition, but approved medical therapies to prevent AAA progression and rupture are currently lacking. Sphingolipid metabolism disorders are associated with the occurrence and development of AAA. It has been discovered that ganglioside GM3, a sialic acid-containing type of glycosphingolipid, plays a protective role in atherosclerosis, which is an important risk factor for AAA; however, the potential contribution of GM3 to AAA development has not been investigated.

METHODS

We performed a metabolomics study to evaluated GM3 level in plasma of human patients with AAA. We profiled GM3 synthase (ST3GAL5) expression in the mouse model of aneurysm and human AAA tissues through Western blotting and immunofluorescence staining. RNA sequencing, affinity purification and mass spectrometry, proteomic analysis, surface plasmon resonance analysis, and functional studies were used to dissect the molecular mechanism of GM3-regulating ferroptosis. We conditionally deleted and overexpressed St3gal5 in smooth muscle cells (SMCs) in vivo to investigate its role in AAA.

RESULTS

We found significantly reduced plasma levels of GM3 in human patients with AAA. GM3 content and ST3GAL5 expression were decreased in abdominal aortic vascular SMCs in patients with AAA and an AAA mouse model. RNA sequencing analysis showed that ST3GAL5 silencing in human aortic SMCs induced ferroptosis. We showed that GM3 interacted directly with the extracellular domain of TFR1 (transferrin receptor 1), a cell membrane protein critical for cellular iron uptake, and disrupted its interaction with holo-transferrin. SMC-specific St3gal5 knockout exacerbated iron accumulation at lesion sites and significantly promoted AAA development in mice, whereas GM3 supplementation suppressed lipid peroxidation, reduced iron deposition in aortic vascular SMCs, and markedly decreased AAA incidence.

CONCLUSIONS

Together, these results suggest that GM3 dysregulation promotes ferroptosis of vascular SMCs in AAA. Furthermore, GM3 may constitute a new therapeutic target for AAA.

Regional and Global Aortic Pulse Wave Velocity in Patients with Abdominal Aortic Aneurysm

OBJECTIVE

Abdominal aortic aneurysm (AAA) is commonly defined as localised aortic dilatation with a diameter > 30 mm. The pathophysiology of AAA includes chronic inflammation and enzymatic degradation of elastin, possibly increasing aortic wall stiffness and pulse wave velocity (PWV). Whether aortic stiffness is more prominent in the abdominal aorta at the aneurysm site is not elucidated. The aim of this study was to evaluate global and regional aortic PWV in patients with AAA.

METHODS

Experimental study of local PWV in the thoracic descending and abdominal aorta in patients with AAA and matched controls. The study cohort comprised 25 patients with an AAA > 30 mm (range 36 - 70 mm, all male, age range 65 - 76 years) and 27 age and sex matched controls free of AAA. PWV was measured with applanation tonometry (carotid-femoral PWV, cfPWV) as well as a 4D flow MRI technique, assessing regional aortic PWV. Blood pressure and anthropometrics were measured.

RESULTS

Global aortic PWV was greater in men with an AAA than controls, both by MRI (AAA 8.9 ± 2.4 m/s vs. controls 7.1 ± 1.5 m/s; p = .007) and cfPWV (AAA 11.0 ± 2.1 m/s vs. controls 9.3 ± 2.3 m/s; p = .007). Regionally, PWV was greater in the abdominal aorta in the AAA group (AAA 7.0 ± 1.8 m/s vs. controls 5.8 ± 1.0 m/s; p = .022), but similar in the thoracic descending aorta (AAA 8.7 ± 3.2 m/s vs. controls 8.2 ± 2.4 m/s; p = .59). Furthermore, PWV was positively associated with indices of central adiposity both in men with AAA and controls.

CONCLUSION

PWV is higher in men with AAA compared with matched controls in the abdominal but not the thoracic descending aorta. Furthermore, aortic stiffness was linked with central fat deposition. It remains to be seen whether there is a causal link between AAA and increased regional aortic stiffness.

Association between the non-HDL-cholesterol to HDL- cholesterol ratio and abdominal aortic aneurysm from a Chinese screening program

BACKGROUND

Abdominal aortic aneurysms (AAAs) can result in high mortality upon rupture but are usually undiagnosed because of the absence of symptoms in the early stage. Ultrasound screening is regarded as an impactful way to prevent the AAA-related death but cannot be performed efficiently; therefore, a target population, especially in Asia, for this procedure is lacking. Additionally, although dyslipidaemia and atherosclerosis are associated with AAA. However, it remains undetermined whether the non-high-density lipoprotein-cholesterol to high-density lipoprotein-cholesterol ratio (NHHR) is associated with AAA. Therefore, this study was aimed at examining whether NHHR is associated with AAA.

METHOD

A total of 9559 participants who underwent AAA screening at Guangdong Provincial People's Hospital and through screening in two communities in Dongguan, from June 2019 to June 2021 joined in this screening program. The diagnosis of AAA was confirmed by the ultrasound examination of the abdominal aorta rather than any known or suspected AAA. Clinical and laboratory data of participants were collected. The participants were separated into a normal group and an AAA group according to the abdominal aortic status. To eliminate confounding factors, a propensity score matching (PSM) approach was utilized. The independent relationship between NHHR and AAA was assessed through the utilization of multivariable logistic regression analysis. In addition, internal consistency was evaluated through subgroup analysis, which controlled for significant risk factors.

RESULTS

Of all the participants, 219 (2.29%) participants were diagnosed with AAA. A significant elevation in NHHR was identified in the AAA group when contrasted with that in the normal group (P < 0.001). As demonstrated by the results of the multivariable logistic regression analysis, AAA was independently associated with NHHR before (odds ratio [OR], 1.440, P < 0.001) and after PSM (OR, 1.515, P < 0.001). Significant extension was observed in the areas under the receiver operating characteristic curves (AUROCs) of NHHR compared to those of single lipid parameters before and after PSM. An accordant association between NHHR and AAA in different subgroups was demonstrated by subgroup analysis.

CONCLUSION

In the Chinese population, there is an independent association between NHHR and AAA. NHHR might be propitious to distinguish individuals with high risk of AAA.

Insulin Dependence is Associated with Poor Long-Term Outcomes Following AAA Repair

BACKGROUND

While prior studies have confirmed the protective effect of diabetes on abdominal aortic aneurysm (AAA) development, much less is known about the effect of diabetes, and in particular insulin dependence, on outcomes following AAA repair. In this study, we aim to evaluate the role of insulin-dependent diabetes on short-term and long-term outcomes following open and endovascular AAA repair.

METHODS

The Vascular Implant Surveillance and Interventional Outcomes Network (VISION), a registry linking the Vascular Quality Initiative (VQI) data with Medicare claims, was queried for patients who underwent open or endovascular AAA repair from 2011 to the present. Exclusion criteria were unknown diabetes status, prior aortic intervention, maximum aneurysm diameter <45 mm at presentation, and Medicare Advantage coverage due to inconsistent follow-up. Patients were stratified based on diabetes status (no diabetes versus diabetes) and insulin dependence (no diabetes or non-insulin-dependent diabetes versus insulin-dependent diabetes).

RESULTS

Of the 38,437 cases in the VISION endovascular aortic aneurysm (EVAR) and open aortic aneurysm repair (OAR) databases, 21,943 met inclusion criteria. Perioperative outcomes after OAR were comparable between diabetic and nondiabetic patients. However, diabetic patients undergoing EVAR were significantly more likely to have a postoperative myocardial infarction (1.0% vs 0.6%, P = 0.04) and have a 30-day readmission (10.9% vs 8.8%, P < 0.001). Insulin-dependent diabetic patients were more likely to require a 30-day readmission after OAR (24.5% vs 13.5%, P = 0.02) and EVAR (15.1% vs 9.0%, P < 0.001); however, only insulin-dependent diabetes mellitus (IDDM) patients undergoing EVAR experienced higher rates of postoperative myocardial infarction (1.9% vs 0.7%, P < 0.01). After propensity score matching, patients with IDDM undergoing EVAR were additionally at increased risk of mortality at 1-year, 3-year, and 5-year follow-up with the highest risk occurring at the 1-year mark (hazard ratio 1.79, P < 0.0001), while IDDM patients undergoing OAR were only at a significantly increased risk of mortality at 5-year follow-up (hazard ratio 1.90, P = 0.01).

CONCLUSIONS

Patients with insulin-dependent diabetes have greater than 14% one-year mortality following open or endovascular aneurysm repair, compared to 8% for all others. Our findings raise questions about whether insulin-dependent diabetics should have a higher size threshold for prophylactic repair, although further studies are needed to address this question and consider the influence of glycemic control on these outcomes.

A review of current status of cell-based therapies for aortic aneurysms

An aortic aneurysm (AA) is defined as focal aortic dilation that occurs mainly with older age and with chronic inflammation associated with atherosclerosis. The aneurysmal wall is a complex inflammatory environment characterized by endothelial dysfunction, macrophage activation, vascular smooth muscle cell (VSMC) apoptosis, and the production of proinflammatory molecules and matrix metalloproteases (MMPs) secreted by infiltrated inflammatory cells such as macrophages, T and B cells, dendritic cells, neutrophils, mast cells, and natural killer cells. To date, a considerable number of studies have been conducted on stem cell research, and growing evidence indicates that inflammation and tissue repair can be controlled through the functions of stem/progenitor cells. This review summarizes current cell-based therapies for AA, involving mesenchymal stem cells, VSMCs, multilineage-differentiating stress-enduring cells, and anti-inflammatory M2 macrophages. These cells produce beneficial outcomes in AA treatment by modulating the inflammatory environment, including decreasing the activity of proinflammatory molecules and MMPs, increasing anti-inflammatory molecules, modulating VSMC phenotypes, and preserving elastin. This article also describes detailed studies on pathophysiological mechanisms and the current progress of clinical trials.

Plasma Lipidomics Analysis Reveals the Potential Role of Lysophosphatidylcholines in Abdominal Aortic Aneurysm Progression and Formation

Abdominal aortic aneurysm (AAA) is hallmarked by irreversible dilation of the infrarenal aorta. Lipid deposition in the aortic wall and the potential importance of a lipid disorder in AAA etiology highlight the need to explore lipid variation during AAA development. This study aimed to systematically characterize the lipidomics associated with AAA size and progression. Plasma lipids from 106 subjects (36 non-AAA controls and 70 AAA patients) were comprehensively analyzed using untargeted lipidomics. An AAA animal model was established by embedding angiotensin-II pump in ApoE^-/- mice for four weeks and blood was collected at 0, 2 and 4 weeks for lipidomic analysis. Using a false-discovery rate (FDR) < 0.05, a group of lysophosphatidylcholines (lysoPCs) were specifically decreased in AAA patients and mice. LysoPCs were principally lower in the AAA patients with larger diameter (diameter > 50 mm) than those with a smaller size (30 mm < diameter < 50 mm), and levels of lysoPCs were also found to be decreased with modelling time and aneurysm formation in AAA mice. Correlation matrices between lipids and clinical characteristics identified that the positive correlation between lysoPCs and HDL-c was reduced and negative correlations between lysoPCs and CAD rate, lysoPCs and hsCRP were converted to positive correlations in AAA compared to control. Weakened positive correlations between plasma lysoPCs and circulating HDL-c in AAA suggested that HDL-lysoPCs may elicit instinctive physiological effects in AAA. This study provides evidence that reduced lysoPCs essentially underlie the pathogenesis of AAA and that lysoPCs are promising biomarkers for AAA development.

Exploring the expression and potential function of follicle stimulating hormone receptor in extragonadal cells related to abdominal aortic aneurysm

INTRODUCTION

Follicle stimulating hormone (FSH) is identified to play a role in postmenopausal disease and hypothesized to affect abdominal aortic aneurysm (AAA) onset/progression in postmenopausal women. We aimed to detect FSHR gene expression in AAA tissue and cell types involved in AAA formation.

METHODS

FSH stimulation of human umbilical cord endothelial cells (HUVECs), smooth muscle cells (HUCs) and PMA-differentiated macrophages to assess gene expression of FSHR and various markers. Human macrophages activated with various stimuli were assessed for FSHR gene expression. AAA dataset, AAA tissue samples and AAA-derived smooth muscle cells (SMC) obtained from elderly female donors were assessed for FSHR gene expression. AAA-SMCs were stimulated with FSH to assess its effect on gene expression. Lastly, oxidized low-density-lipoprotein (ox-LDL) uptake and abundance of cell surface protein markers were assessed by flow cytometry after FSH stimulation of human monocytes.

RESULTS

FSH stimulation showed similar levels of gene expression in HUVECs and HUCs. Only ACTA2 was downregulated in HUCs. In PMA-differentiated macrophages, gene expression of inflammation markers was unchanged after FSH stimulation. FSHR gene expression was found to be low in the AAA datasets. Female AAA-SMCs show occasional FSHR gene expression at a very low level, yet stimulation with FSH did not affect gene expression of SMC- or inflammation markers. FSH stimulation did not impact ox-LDL uptake or alter cell surface protein expression in monocytes. While FSHR gene expression was detected in human testis tissue, it was below quantification level in all other investigated cell types, even upon activation of macrophages with various stimuli.

CONCLUSION

Despite previous reports, we did not detect FSHR gene expression in various extragonadal cell types, except in occasional female AAA-SMCs. No clear effect on cell activation was observed upon FSH stimulation in any cell type. Our data suggest that a direct effect of FSH in AAA-related extragonadal cells is unlikely to influence AAA.

Racial and ethnic differences in presentation severity and postoperative outcomes in vascular surgery

BACKGROUND

We assessed the effect of race and ethnicity on presentation severity and postoperative outcomes in those with abdominal aortic aneurysms (AAAs), carotid artery stenosis (CAS), peripheral arterial disease (PAD), and type B aortic dissection (TBAD).

METHODS

MEDLINE, Embase, and Cochrane Central Register of Controlled Trials from inception until December 2020. Two reviewers independently selected randomized controlled trials and observational studies reporting race and/or ethnicity and presentation severity and/or postoperative outcomes for adult patients who had undergone major vascular procedures. They independently extracted the study data and assessed the risk of bias using the Newcastle-Ottawa scale. The meta-analysis used random effects models to derive the odds ratios (ORs) and risk ratios (RRs) and their corresponding 95% confidence intervals (CIs). The primary outcome was presentation severity stratified by the proportion of patients with advanced disease, including ruptured vs nonruptured AAA, symptomatic vs asymptomatic CAS, chronic limb-threatening ischemia vs claudication, and complicated vs uncomplicated TBAD. The secondary outcomes included postoperative all-cause mortality and disease-specific outcomes.

RESULTS

A total of 81 studies met the inclusion criteria. Black (OR, 4.18; 95% CI, 1.31-13.26), Hispanic (OR, 2.01; 95% CI, 1.85-2.19), and Indigenous (OR, 1.97; 95% CI, 1.39-2.80) patients were more likely to present with ruptured AAAs than were White patients. Black and Hispanic patients had had higher symptomatic CAS (Black: OR, 1.20; 95% CI, 1.04-1.38; Hispanic: OR, 1.32; 95% CI, 1.20-1.45) and chronic limb-threatening ischemia (Black: OR, 1.67; 95% CI, 1.14-2.43; Hispanic: OR, 1.73; 95% CI 1.13-2.65) presentation rates. No study had evaluated the effect of race or ethnicity on complicated TBAD. All-cause mortality was higher for Black (RR, 1.23; 95% CI, 1.01-1.51), Hispanic (RR, 1.90; 95% CI, 1.57-2.31), and Indigenous (RR, 1.24; 95% CI, 1.12-1.37) patients after AAA repair. Postoperatively, Black (RR, 1.54; 95% CI, 1.19-2.00) and Hispanic (RR, 1.54; 95% CI, 1.31-1.81) patients were associated with stroke/transient ischemic attack after carotid revascularization and lower extremity amputation (RR, 1.90; 95% CI, 1.76-2.06; and RR, 1.69; 95% CI, 1.48-1.94, respectively).

CONCLUSIONS

Certain visible minorities were associated with higher morbidity and mortality across various vascular surgery presentations. Further research to understand the underpinnings is required.

Genetic Association between the Levels of Plasma Lipids and the Risk of Aortic Aneurysm and Aortic Dissection: A Two-Sample Mendelian Randomization Study

Although a growing number of studies have attempted to uncover the relationship between plasma lipids and the risk of aortic aneurysm (AA), it remains controversial. Meanwhile, the relationship between plasma lipids and the risk of aortic dissection (AD) has not been reported on. We conducted a two-sample Mendelian randomization (MR) analysis to evaluate the potential relationship between genetically predicted plasma levels of lipids and the risk of AA and AD. Summary data on the relationship between genetic variants and plasma lipids were obtained from the UK Biobank and Global Lipids Genetics Consortium studies, and data on the association between genetic variants and AA or AD were taken from the FinnGen consortium study. Inverse-variance weighted (IVW) and four other MR analysis methods were used to evaluate effect estimates. Results showed that genetically predicted plasma levels of low-density lipoprotein cholesterol, total cholesterol, or triglycerides were positively correlated with the risk of AA, and plasma levels of high-density lipoprotein cholesterol were negatively correlated with the risk of AA. However, no causal relationship was found between elevated lipid levels and the risk of AD. Our study revealed a causal relationship between plasma lipids and the risk of AA, while plasma lipids had no effect on the risk of AD.

The neglected association between central obesity markers and abdominal aortic aneurysm presence: A systematic review and meta-analysis

Purpose

To review the association between central obesity and abdominal aortic aneurysm (AAA).

Materials and methods

The PubMed, Web of Sciences, Embase, The China national knowledge infrastructure (CNKI), and Cochrane Library were searched up to April 30, 2022. Researches includes investigation of the relationship between central obesity markers and AAA. Included studies must use recognized measures of central obesity, i.e., waist circumference (WC) and waist-to-hip ratio (WHR), or use imaging techniques to calculate abdominal fat distribution, such as computed tomography (CT) imaging.

Results

Eleven clinical researches were identified of which eight discussed the association between physical examination and AAA, and three studies mainly focused on abdominal fat volume (AFV). Seven researches concluded that there was a positive correlation between markers of central obesity and AAA. Three studies found no significant link between markers of central obesity and AAA. One of the remaining studies reported different results for each sex. Three studies pooled in a meta-analysis identified correlation between central obesity and AAA presence (RR = 1.29; 95% confidence interval, 1.14-1.46).

Conclusion

Central obesity plays a role in the risk of AAA. Standardized central obesity markers may be predictors of AAA. However, there was no association between abdominal fat volume and AAA. Additional relevant evidence and specific mechanisms warrant further study.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?IDCRD42022332519, identifier CRD42022332519.

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.

Dose-dependent relationship of blood pressure and glycaemic status with risk of aortic dissection and aneurysm

AIMS

Data on the dose-dependent association of blood pressure (BP) and fasting plasma glucose (FPG) level with the risk of aortic dissection (AD) and aortic aneurysm (AA) are limited.

METHODS AND RESULTS

This observational cohort study included 3 358 293 individuals registered in a health checkup and claims database in Japan [median age, 43 (36-51) years; 57.2% men]. Individuals using BP- or glucose-lowering medications or those with a history of cardiovascular disease were excluded. In a mean follow-up period of 1 199 ± 950 days, 1 095 and 2 177 cases of AD and AA, respectively, were recorded. Compared with normal/elevated BP, hazard ratios (HRs) of Stage 1 and Stage 2 hypertension were 1.89 [95% confidence interval (CI): 1.60-2.22] and 5.87 (95% CI: 5.03-6.84) for AD and 1.37 (95% CI: 1.23-1.52) and 2.17 (95% CI: 1.95-2.42) for AA, respectively. Compared with normal FPG level, HRs of prediabetes and diabetes were 0.82 (95% CI: 0.71-0.94) and 0.48 (95% CI: 0.33-0.71) for AD and 0.94 (95% CI: 0.85-1.03) and 0.61 (95% CI: 0.47-0.79) for AA, respectively. The cubic spline demonstrated that the risk of AD and AA increased with increasing BP but decreased with increasing FPG level. Contour plots using generalized additive models showed that higher systolic BP and lower FPG level were associated with an elevated risk of AD and AA.

CONCLUSIONS

Our analysis showed a dose-dependent increase in the risk of AD or AA associated with BP and a similar decrease associated with FPG, and also suggested a potential interaction between hypertension and hyperglycaemia in the development of AD and AA.

Association of neutrophils, lymphocytes, and neutrophil-lymphocyte ratio to overall mortality after endovascular abdominal aortic aneurysm repair

BACKGROUND

The purpose of this study was to determine the predictive ability of neutrophilia, lymphocytopenia, and neutrophil-lymphocyte ratio (NLR) for overall mortality after EVAR for AAA.

METHODS

Data on patients with AAA treated by EVAR between March 2012 and December 2016 were obtained from a prospectively maintained EVAR database at Tokyo Medical University Hospital. The NLR was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count. A cut-off value of total WBC count, neutrophil count, lymphocyte count, and NLR was determined according to a receiver operating characteristic (ROC) curve. Univariate and multivariate analyses were performed using the Cox proportional hazard analyses to account for the time at risk.

RESULTS

178 patients were included in this study after selection based on the exclusion criteria. The subjects consisted of 150 men and 28 women with a mean age of 77.5 years (range, 51-89 years). A ROC curve analysis determined the optimal cut-off values of preoperative total WBC, neutrophils, lymphocytes, and NLR for predicting overall mortality with 7,050 /μL, 4,012 /μL, 1,312 /μL, and 3.19, respectively. On univariate analysis and multivariate analyses, octogenarian, obesity, COPD, active cancer, and lymphocytopenia or NLR were detected as independent predictors for overall mortality.

CONCLUSIONS

Specific leukocyte populations, such as lymphocyte count and NLR, are useful biomarkers to predict overall mortality in patients undergoing EVAR for AAA, suggesting that WBC count and its subsets, which are easy to perform a test, may be used to stratify patients at risk for poor prognosis following EVAR.

Fibrates: A Possible Treatment Option for Patients with Abdominal Aortic Aneurysm?

Abdominal aortic aneurysm (AAA) is a life-threatening disease; however, there is no established treatment for patients with AAA. Fibrates are agonists of peroxisome proliferator-activated receptor alpha (PPARα) that are widely used as therapeutic agents to treat patients with hypertriglyceridemia. They can regulate the pathogenesis of AAA in multiple ways, for example, by exerting anti-inflammatory and anti-oxidative effects and suppressing the expression of matrix metalloproteinases. Previously, basic and clinical studies have evaluated the effects of fenofibrate on AAA. In this paper, we summarize the results of these studies and discuss the problems associated with using fenofibrate as a therapeutic agent for patients with AAA. In addition, we discuss a new perspective on the regulation of AAA by PPARα agonists.

AAA Revisited: A Comprehensive Review of Risk Factors, Management, and Hallmarks of Pathogenesis

Despite declining incidence and mortality rates in many countries, the abdominal aortic aneurysm (AAA) continues to represent a life-threatening cardiovascular condition with an overall prevalence of about 2-3% in the industrialized world. While the risk of AAA development is considerably higher for men of advanced age with a history of smoking, screening programs serve to detect the often asymptomatic condition and prevent aortic rupture with an associated death rate of up to 80%. This review summarizes the current knowledge on identified risk factors, the multifactorial process of pathogenesis, as well as the latest advances in medical treatment and surgical repair to provide a perspective for AAA management.

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.

Height and Mortality from Aortic Aneurysm and Dissection

AIMS

Reports on the association between height and aortic disease have been modest, and there are only a few studies investigating the association between height and mortality from specific aortic disease types or by sex.

METHODS

We conducted the Japan Collaborative Cohort Study, a prospective study of 99,067 Japanese (41,730 men and 57,337 women) aged 40-79 years old. Height was self-reported, and the participants were followed up from 1988-1989 to the end of 2009. Sex-specific hazard ratios (95% confidence intervals) of mortality from aortic disease type according to sex-specific quartiles of height were analyzed using the Cox proportional hazards model.

RESULTS

During the median follow-up period of 19.1 years, the numbers of deaths due to aortic aneurysm, thoracic aortic aneurysm, abdominal aortic aneurysm, and aortic dissection were 87, 29, 48, and 56 among men and 35, 17, 15, and 65 among women, respectively. The sex-specific multivariate hazard ratios (95% confidence intervals) and p for trend for the highest versus lowest quartiles of height were 1.10 (0.66-1.83), p=0.58 among men and 1.54 (0.85-2.79), p=0.06 among women for total aortic disease; 1.85 (0.80-4.28), p=0.16 among men and 5.67 (0.90-35.77), p=0.08 among women for abdominal aortic aneurysm; and 1.13 (0.48-2.64), p=0.65 among men and 1.70 (0.82-3.50), p=0.04 among women for aortic dissection. The positive association was observed for both sexes, albeit more prominent among women. No association was found between height and mortality from thoracic aortic aneurysms.

CONCLUSIONS

As per our findings, we were able to determine that height was positively associated with mortality from abdominal aortic aneurysm in the Japanese population.

Advanced Research of Abdominal Aortic Aneurysms on Metabolism

Abdominal aortic aneurysm (AAA) is a cardiovascular disease with a high risk of death, seriously threatening the life and health of people. The specific pathogenesis of AAA is still not fully understood. In recent years, researchers have found that amino acid, lipid, and carbohydrate metabolism disorders play important roles in the occurrence and development of AAA. This review is aimed to summarize the latest research progress of the relationship between AAA progression and body metabolism. The body metabolism is closely related to the occurrence and development of AAA. It is necessary to further investigate the pathogenesis of AAA from the perspective of metabolism to provide theoretical basis for AAA diagnosis and drug development.

Association of Abdominal Aortic Aneurysm and Simple Renal Cysts: A Systematic Review and Meta-Analysis

BACKGROUND-OBJECTIVE

Prior studies have suggested a higher prevalence of simple renal cysts (SRC) among patients with aortic disease, including abdominal aortic aneurysms (AAA). Thus, the aim of this study was to systematically review all currently available literature and investigate whether patients with AAA are more likely to have SRC.

METHODS

This study was performed according to the PRISMA guidelines. A meta-analysis was conducted with the use of random effects modeling and the I-square was used to assess heterogeneity. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) were synthesized to compare the prevalence of several patients' characteristics between AAA vs. no-AAA cases.

RESULTS

Eleven retrospective studies, 9 comparative (AAA vs. no-AAA groups) and 3 single-arm (AAA group), were included in this meta-analysis, enrolling patients (AAA: N = 2,297 vs. no-AAA: N = 35,873) who underwent computed tomography angiography as part of screening or preoperative evaluation for reasons other than AAA. The cumulative incidence of SRC among patients with AAA and no-AAA was 55% (95% CI: 49%-61%) and 32% (95% CI: 22%-42%) respectively, with a statistically higher odds of SRC among patients with AAA (OR: 3.02; 95% CI: 2.01-4.56; P< 0.001). The difference in SRC prevalence remained statistically significant in a sensitivity analysis, after excluding the study with the largest sample size (OR: 2.71; 95% CI: 1.91-3.84; P< 0.001).

CONCLUSIONS

Our meta-analysis demonstrated a 3-fold increased prevalence of SRC in patients with AAA compared to no-AAA cases, indicating that the pathogenic processes underlying SRC and AAA could share a common pathophysiologic mechanism. Thus, patients with SRC could be considered at high risk for AAA formation, potentially warranting an earlier AAA screening.

[Summary of the S3 guideline on abdominal aortic aneurysm from an anesthesiological perspective]

The current article is a summary of the 2018 revised S3 guideline on screening, diagnosis, therapy, and follow-up of the abdominal aortic aneurysm (AAA) from an anesthesiological point of view. It is the only interdisciplinary guideline that describes in particular the perioperative anesthesiological and intensive care management.

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.

Physical activity and the risk of abdominal aortic aneurysm: a systematic review and meta-analysis of prospective studies

The association between physical activity and risk of abdominal aortic aneurysm has been inconsistent with some studies reporting a reduced risk while others have found no association. We conducted a systematic review and meta-analysis of prospective studies to quantify the association. PubMed and Embase databases were searched up to 3 October 2020. Prospective studies were included if they reported adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) of abdominal aortic aneurysm associated with physical activity. Summary RRs (95% CIs) were estimated using a random effects model. Nine prospective studies (2073 cases, 409,732 participants) were included. The summary RR for high vs. low physical activity was 0.70 (95% CI: 0.56-0.87, I2 = 58%) and per 20 metabolic equivalent task (MET)-hours/week increase of activity was 0.84 (95% CI: 0.74-0.95, I2 = 59%, n = 6). Although the test for nonlinearity was not significant (p = 0.09) the association appeared to be stronger when increasing the physical activity level from 0 to around 20-25 MET-hours/week than at higher levels. The current meta-analysis suggest that higher physical activity may reduce the risk of abdominal aortic aneurysm, however, further studies are needed to clarify the dose-response relationship between different subtypes and intensities of activity and abdominal aortic aneurysm risk.

Diabetes, its duration, and the long-term risk of abdominal aortic aneurysm: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND AND AIMS

We aimed at comprehensively evaluate the independent association of diabetes and its duration with incident abdominal aortic aneurysm (AAA) and aortic diameter.

METHODS AND RESULTS

We prospectively studied incident AAA according to baseline glycemic status (diabetes, prediabetes, normal glycemia) in 13,116 ARIC participants (1990-1992) and the time-varying exposure of duration post incident diabetes in 11,675 participants (1987-1989) using Cox models. Additionally, we cross-sectionally explored ultrasound-based abdominal aortic diameter by glycemic status and cumulative duration of diabetes in 4710 participants (2011-2013) using linear regression models. Over ~20 years of follow-up, diabetes (vs. normal glycemia) at baseline was independently associated with lower AAA risk (489 cases) (hazard ratio: 0.71 [95%CI 0.51-0.99]), especially after 10 years (hazard ratio: 0.58 [0.38-0.87]). Prediabetes did not demonstrate an independent association. The inverse association was more evident with longer duration of diabetes (p for trend = 0.045), with 30-50% lower risk in eight years after diabetes diagnosis. The cross-sectional analysis demonstrated smaller aortic diameters with longer duration of diabetes (e.g., -0.76 mm [-1.24, -0.28] in diabetes with 8-12 years) compared to non-diabetes, whereas prediabetes consistently showed nominally greater diameter.

CONCLUSIONS

Diabetes, especially with longer duration, but not prediabetes, was independently associated with lower risk of AAA and smaller aortic diameter. Our findings suggest that long lasting clinical hyperglycemia plays an important role in the reduced AAA risk, and the reduced aortic diameter may be a structural mechanism behind this paradoxical association.

The association between simple renal cyst and aortic diseases: A systematic review and meta-analysis of observational studies

OBJECTIVE

The objective of this meta-analysis of observational studies was to evaluate the association between simple renal cysts (SRC) and presence of aortic pathology such as aortic aneurysms and dissection.

METHODS

We conducted searches in Ovid MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials from January 1960 to August 2019 to identify observational studies that examined the association between SRCs and any aortic diseases, including aortic aneurysms and dissection. Two reviewers independently extracted the data and assessed the risk of bias. The meta-analysis was performed by STATA 14.1.

RESULTS

In total, 11 observational studies with 19 719 participants were included in this meta-analysis. Compared to individuals without SRCs, patients with SRCs had higher odds of abdominal aortic aneurysm (AAA) (adjusted OR = 2.61, 95% CI 2.34-2.91, P < 0.001, I²   = 0%), ascending thoracic aortic aneurysm (TAA) (adjusted OR = 1.98, 95% CI 1.09-3.63, P = 0.03, I²   = 90.1%), descending TAA (adjusted OR = 3.44, 95% CI, 2.67-4.43, P < 0.001, I²   = 0%), type A aortic dissection (AD) (adjusted OR = 1.98, 95% CI 1.32-2.96, P = 0.001, I²   = 12.9%), and type B AD (adjusted OR = 2.55, 95% CI, 1.31-4.96, P = 0.006, I²   = 76.2%). There was a higher average in the sum of diameter of SRCs among AAA compared to patients without AAA (WMD = 19.80 mm, 95% CI 13.92-25.67, P < 0.001, I²   = 63.8%).

CONCLUSION

SRC is associated with higher odds of aortic diseases including AAA, ascending and descending TAA, type A and type B dissection even after adjusting for confounders.

Leukocyte subsets and abdominal aortic aneurysms detected by screening in men

OBJECTIVE

In the present case-control study, we describe the associations between leukocyte subsets in blood and early, screening-detected AAA in men. An abdominal aortic aneurysm (AAA) may result in a life-threatening rupture of the aortic wall. The trigger for AAA formation remains unknown, but the vascular adventitia of advanced AAAs is infiltrated by various leukocytes, indicating that the pathogenesis may involve inflammation.

METHODS

In Sweden, all 65-year-old men are invited to an ultrasound examination for detection of AAA. At the Gothenburg screening site, 16 256 men were examined in 2013-2017, 1.2% of whom had an AAA (diameter of the infrarenal aorta ≥30 mm). All men with AAA at screening as well as a randomized selection of AAA-free screened men were invited to participate in a case-control study.

RESULTS

The median diameter of AAAs was 33 mm. Men with an AAA (n = 151) had a higher frequency of smoking, hypertension and statin use than controls (n = 224). Blood levels of neutrophils, lymphocytes, monocytes and basophils were higher in individuals with an AAA, but eosinophil count did not differ from controls. Odds ratios (95% confidence interval) for AAA were 8.6 (4.2-17.4), 3.5 (1.9-6.6) and 3.3 (1.8-6.3) for the highest versus lowest quartile of neutrophils, lymphocytes and monocytes, respectively. For neutrophils and lymphocytes, the association with AAA remained significant after adjustment for smoking and other known risk factors/markers.

CONCLUSION

Several, but not all, subsets of circulating leukocytes are associated with screening-detected AAA in men, which is insufficiently explained by associations with smoking and other confounders.

Association between metformin and abdominal aortic aneurysm in diabetic and non-diabetic US veterans

We sought to examine the progression from abdominal aortic aneurysm (AAA) diagnosis to surgery and death among diabetics with and without exposure to metformin as well as non-diabetics. We conducted a retrospective cohort study (January 2000 to July 2019) comparing 3 transitions (AAA surgery, death, and death after AAA surgery) among propensity score-matched metformin-exposed and unexposed diabetic veterans and non-diabetic veterans using the VA Informatics and Computing Infrastructure database. We fit an adjusted Cox proportional hazards model with transition-specific effects. There were 43,073 metformin-unexposed diabetics, 24,361 metformin-exposed diabetics and 56,006 non-diabetics. Compared with the non-diabetic cohort, both diabetic cohorts have a lower risk of surgery (no metformin (HR=0.740, 95% CI 0.706 to 0.776); with metformin (HR=0.770, 95% CI 0.730 to 0.813)). However, the non-metformin diabetic cohort has a higher risk of death (HR=1.024, 95% CI 1.004 to 1.045) and death after surgery (HR=1.086, 95% CI 1.013 to 1.165). The metformin-exposed diabetic cohort has a lower risk of death in the first 10 years after AAA diagnosis (HR=0.877, 95% CI 0.855 to 0.899), yet a higher risk of death 10 years after AAA diagnosis (HR=1.177, 95% CI 1.092 to 1.270) compared with non-diabetic cohort. Non-diabetics have the highest rate of AAA surgery compared with both diabetic cohorts. However, diabetics without metformin have the highest risk of death prior to, and after surgery. This research provides novel findings for patients diagnosed with AAA. The use of metformin after both AAA diagnosis and surgery should be further investigated.

Symptoms of Depression and Risk of Abdominal Aortic Aneurysm: A HUNT Study

Background

Depression is associated with cardiovascular diseases, but the evidence is scarce regarding depression and risk of abdominal aortic aneurysms (AAA). The aim was to determine whether individuals with depressive symptoms have increased risk of AAA.

Methods and Results

This population‐based prospective study included 59 136 participants (52.4% women) aged 50 to 106 years from the HUNT (Norwegian Nord‐Trøndelag Health Study). Symptoms of depression were assessed using the depression subscale of the Hospital Anxiety and Depression Scale (HADS). During a median follow‐up of 13 years, there were 742 incident cases of AAA (201 women). A total of 6401 individuals (12.3%) reported depressive symptoms (defined as HADS depression scale [HADS‐D]) ≥8) (52.5% women). The annual incidence rate of AAA was 1.0 per 1000 individuals. At all ages, the estimated proportion of individuals diagnosed with AAA was higher among those with depressive symptoms (log‐rank test, P<0.001). People with HADS‐D ≥8 were older than those with HADS‐D<8 (median 57.8 versus 52.3 years, P<0.001) and a statistically significantly higher proportion of them (P<0.001) were smokers, overweight or obese, and reported a history of coronary heart disease, diabetes mellitus, and hypertension. In a Cox proportional hazard regression model adjusted for these factors, individuals with depressive symptoms had a ≈30% higher risk of AAA than those without (hazard ratio, 1.32, 95% CI 1.08–1.61, P=0.007).

Conclusions

This study shows that individuals with depressive symptoms have significantly higher risk of incident AAA, after adjustments for established risk factors.

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.

Kidney function, proteinuria and breast arterial calcification in women without clinical cardiovascular disease: The MINERVA study

BACKGROUND

Breast arterial calcification (BAC) may be a predictor of cardiovascular events and is highly prevalent in persons with end-stage kidney disease. However, few studies to date have examined the association between mild-to-moderate kidney function and proteinuria with BAC.

METHODS

We prospectively enrolled women with no prior cardiovascular disease aged 60 to 79 years undergoing mammography screening at Kaiser Permanente Northern California between 10/24/2012 and 2/13/2015. Urine albumin-to-creatinine ratio (uACR), along with specific laboratory, demographic, and medical data, were measured at the baseline visit. Baseline estimated glomerular filtration rate (eGFR), medication history, and other comorbidities were identified from self-report and/or electronic medical records. BAC presence and gradation (mass) was measured by digital quantification of full-field mammograms.

RESULTS

Among 3,507 participants, 24.5% were aged ≥70 years, 63.5% were white, 7.5% had eGFR <60 ml/min/1.73m2, with 85.7% having uACR ≥30 mg/g and 3.3% having uACR ≥300 mg/g. The prevalence of any measured BAC (>0 mg) was 27.9%. Neither uACR ≥30 mg/g nor uACR ≥300 were significantly associated with BAC in crude or multivariable analyses. Reduced eGFR was associated with BAC in univariate analyses (odds ratio 1.53, 95% CI: 1.18-2.00), but the association was no longer significant after adjustment for potential confounders. Results were similar in various sensitivity analyses that used different BAC thresholds or analytic approaches.

CONCLUSIONS

Among women without cardiovascular disease undergoing mammography screening, reduced eGFR and albuminuria were not significantly associated with BAC.

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.

Diabetes mellitus and the risk of abdominal aortic aneurysm: A systematic review and meta-analysis of prospective studies

BACKGROUND

Diabetes mellitus has been associated with reduced risk of abdominal aortic aneurysm in a number of epidemiological studies, however, until recently little data from prospective studies have been available. We therefore conducted a systematic review and meta-analysis of prospective studies to quantify the association.

MATERIAL AND METHODS

Two investigators searched the PubMed and Embase databases for studies of diabetes and abdominal aortic aneurysm up to May 8th 2018. Prospective studies were included if they reported adjusted relative risk (RR) estimates and 95% confidence intervals (95% CIs) of abdominal aortic aneurysm associated with a diabetes diagnosis. Summary relative risks were estimated by use of a random effects model.

RESULTS

We identified 16 prospective studies with 16,572 cases among 4,563,415 participants that could be included in the meta-analysis. The summary RR for individuals with diabetes compared to individuals without diabetes was 0.58 (95% CI: 0.51-0.66, I² = 40.4%, p_{heterogeneity} = 0.06). The results persisted when stratified by sex, duration of follow-up, and in most of the other subgroup analyses. There was no evidence of publication bias with Egger's test, p = 0.64 or by inspection of the funnel plots.

CONCLUSIONS

These results suggest that individuals with diabetes mellitus are at a reduced risk of abdominal aortic aneurysm, however, whether pharmacological agents for diabetes mellitus explain this observation needs to be clarified in future studies.

Tobacco smoking and the risk of abdominal aortic aneurysm: a systematic review and meta-analysis of prospective studies

Several studies have found that smoking increases the risk of abdominal aortic aneurysm, however, the strength of the association has differed between studies and data from cohort studies have not yet been summarized. A systematic review and meta-analysis was therefore conducted to clarify this association. We searched PubMed and Embase databases up to May 2nd 2018. A random effects model was used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs). Twenty three prospective studies were included. Comparing current, former and ever smokers with never smokers the summary RRs were 4.87 (95% CI: 3.93-6.02, I2 = 92%, n = 20), 2.10 (95% CI: 1.76-2.50, I2 = 71%, n = 15) and 3.28 (95% CI: 2.60-4.15, I2 = 96%, n = 18), respectively. The summary RR was 1.87 (95% CI: 1.45-2.40, I2 = 97%) per 10 cigarettes per day, 1.78 (95% CI: 1.54-2.06, I2 = 83%) per 10 pack-years was and 0.45 (95% CI: 0.32-0.63, I2 = 92.3%) per 10 years of smoking cessation. There was evidence of nonlinearity for cigarettes per day and pack-years (pnonlinearity < 0.0001 and pnonlinearity = 0.02, respectively), but not for smoking cessation, pnonlinearity = 0.85. Among smokers who quit, the RR was similar to that of never smokers by 25 years of smoking cessation. These findings confirm a strong association between smoking and the risk of developing abdominal aortic aneurysms.

Analysis of the Correlation Between Central Obesity and Abdominal Aortic Diseases

BACKGROUND

Atherosclerosis and abdominal aortic aneurysms (AAAs) have several similar risk factors but different pathogenesis. Inflammation of the arteries is common to both. Central obesity can act as an endocrine organ through the secretion of inflammatory cytokines, and the perivascular fat has a local effect that could contribute to diseases of the abdominal aorta. Although the relation between central obesity and atherosclerosis occlusive arterial disease has been demonstrated, the correlation with AAA has conflicting results. The aim of this study was to analyze the correlation between central obesity and the presence of abdominal aortic diseases using computed tomography.

METHODS

Six hundred thirty-nine consecutive patients classified into 3 groups (AAA, aortic atherosclerotic occlusive disease (AAOD), and without aortic disease [control group]) who underwent computed tomography had the aorta diameter, the visceral fat area (VFA), and the subcutaneous fat area (SFA) measured at the level of third and fourth lumbar vertebrae.

RESULTS

VFA showed no difference between the groups. SFA was lower in atherosclerotic group (AAOD) than control (P < 0.01 in general and P < 0.04 in male). In AAA group, we found in men that the first tertile of aorta diameter had higher VFA than third tertile (P = 0.02).

CONCLUSIONS

There was no difference in VFA between patients in AAA, AAOD, and without aortic disease groups. In men with aneurysm, there was an inverse relationship between VFA and aortic diameter. In AAOD, visceral to subcutaneous ratio is higher due to lower SFA.

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?

Association of carotid atherosclerosis and stiffness with abdominal aortic aneurysm: The atherosclerosis risk in communities (ARIC) study

BACKGROUND AND AIMS

Individuals with atherosclerosis and stiffness often have increased abdominal aortic diameters, but prospective evidence linking them to the risk of abdominal aortic aneurysm (AAA) is limited.

METHODS

We prospectively examined the relationship of carotid atherosclerosis and stiffness with future risk of AAA in ARIC. At Visits 1 (1987-89) or 2 (1990-1992), we assessed carotid atherosclerosis (represented by greater carotid intima-media thickness [cIMT] or presence of atherosclerotic plaque) and lower carotid distensibility (reflected by a higher carotid Beta Index). We identified incident, clinical AAAs during follow-up through 2011 using hospital discharge codes, Medicare outpatient diagnoses, or death certificates.

RESULTS

Participants' mean age at baseline was 54.2 years (SD 5.8), 45% were male and 73% white. During a median of 22.5 years of follow-up, 542 clinical AAAs were ascertained. After multivariable adjustment, the presence of carotid atherosclerotic plaque at baseline was associated with 1.31 (95% CI: 1.10-1.57; p = 0.003) times higher risk of clinical AAA. Greater cIMT and Beta Index were also associated with clinical AAA with a dose-response across quartiles (p trend for both: 0.006; hazard ratios [95% CI] for the highest vs. lowest quartiles: 1.55 [1.13-2.11] and 1.68 [1.16-2.43], respectively). The associations of cIMT and Beta Index with AAA were independent of each other.

CONCLUSIONS

This prospective population-based study found that indices of greater carotid atherosclerosis and lower carotid distensibility are markers of increased AAA risk.

Pre-admission proteinuria impacts risk of non-recovery after dialysis-requiring acute kidney injury

Renal recovery after dialysis-requiring acute kidney injury (AKI-D) is an important clinical and patient-centered outcome. Here we examined whether the pre-admission proteinuria level independently influences risk for non-recovery after AKI-D in a community-based population. All adult members of Kaiser Permanente Northern California who experienced AKI-D between January 1, 2009 and September 30, 2015 were included. Pre-admission proteinuria levels were determined by dipstick up to four years before the AKI-D hospitalization and the outcome was renal recovery (survival and dialysis-independence four weeks and more) at 90 days after initiation of renal replacement therapy. We used multivariable logistic regression to adjust for baseline estimated glomerular filtration rate (eGFR), age, sex, ethnicity, short-term predicted risk of death, comorbidities, and medication use. Among 5,347 adults with AKI-D, the mean age was 66 years, 59% were men, and 50% were white. Compared with negative/trace proteinuria, the adjusted odds ratios for non-recovery (continued dialysis-dependence or death) were 1.47 (95% confidence interval 1.19-1.82) for 1+ proteinuria and 1.92 (1.54-2.38) for 2+ or more proteinuria. Among survivors, the crude probability of recovery ranged from 83% for negative/trace proteinuria with baseline eGFR over 60 mL/min/1.73m² to 25% for 2+ or more proteinuria with eGFR 15-29 mL/min/1.73m². Thus, the pre-AKI-D level of proteinuria is a graded, independent risk factor for non-recovery and helps to improve short-term risk stratification for patients with AKI-D.

Infrarenal aortic diameter, aortoiliac bifurcation level and lumbar disc degenerative changes: a cross-sectional MR study

PURPOSE

To examine a possible correlation of infrarenal aortic diameter and aortoiliac bifurcation level with lumbar disc degenerative changes.

METHODS

This was a cross-sectional, single-center retrospective study on lumbar magnetic resonance images of patients with low back pain (n = 496). Lumbar disc degenerative changes were reported on the basis of the Pfirrmann grading system and accordingly, patients were grouped as with grade I-II findings (n = 192), with grade III findings (n = 64) and with grade IV-V findings (n = 240). The groups were matched for sex, body mass index and the history of diabetes mellitus, hypertension, hyperlipidemia and smoking. Infrarenal aortic diameter and aortoiliac bifurcation level were compared between the three groups.

RESULTS

Pairwise comparisons between the three groups of patients with Pfirrmann grades of I-II, III and IV-V revealed significant differences (p < 0.05) in terms of the median infrarenal aortic diameter (17 mm [interquartile range 4], 18 mm [4] and 19 mm [4], respectively) and the median aortoiliac bifurcation level (3 [2], 4 [2] and 5 [3], respectively; the higher the value, the more the caudal displacement). These associations were independent of conventional risk factors of atherosclerosis (including age) and from each other.

CONCLUSIONS

This study showed a significant, direct correlation of the infrarenal aortic diameter and the level of aortoiliac bifurcation with lumbar intervertebral degenerative changes according to the Pfirrmann grading system. The associations were independent of well-known risk factors of atherosclerosis and from each other.

MicroRNAs and Current Concepts on the Pathogenesis of Abdominal Aortic Aneurysm

OBJECTIVE

Abdominal aortic aneurysm is an important cause of morbidity and mortality in the elderly. Currently, the only way to prevent rupture and death related to abdominal aortic aneurysms is through surgical intervention. Endovascular treatment is associated with less morbidity than conventional treatment. The formation of an aneurysm is a complex multifactorial process, involving destructive remodeling of the connective tissue around the affected segment of the aorta wall. MicroRNAs are small sequences of non-coding RNAs that control diverse cellular functions by promoting degradation or inhibition of translation of specific mRNAs. A profile aberrant expression of miRNAs has been linked to human diseases, including cardiovascular dysfunction.

Meta-analysis of the association between alcohol consumption and abdominal aortic aneurysm

Background

Alcohol is a possible risk factor for abdominal aortic aneurysm (AAA), but evidence from individual studies is weak and inconsistent. Existing narrative reviews suggest the possibility of non-linear associations. The aim here was to quantify any association using a systematic literature review, followed by dose–response meta-analysis of prospective studies.

Methods

MEDLINE, Embase and Web of Science were searched systematically to January 2017 for relevant prospective studies of alcohol consumption and AAA risk. Summary estimates of highest versus lowest levels of consumption, and linear and non-linear dose–response curves were quantified using random-effects models.

Results

Eleven relevant cohorts were identified describing results from 3580 individuals with among 473 092 participants. Data were extracted from ten cohorts for meta-analyses of high versus low levels of alcohol consumption (risk ratio for AAA 0·93, 95 per cent c.i. 0·78 to 1·11; P = 0·4, I2 = 47 per cent). The linear dose–response risk ratio for AAA, derived from 11 cohorts, was 1·00 (0·97 to 1·04) per 8 g alcohol per day (P = 0·9, I2 = 73 per cent). Non-linear dose–response results showed a tick-shaped curve with lower risk up to 2 units/day, but increasing risk beyond that (P = 0·05). The increase in risk beyond 2 units/day was stronger in men than in women.

Conclusion

Although the linear dose–response analysis revealed little evidence of an association between alcohol consumption and AAA risk, a tick-shaped trend in the association was observed. This non-linear dose–response analysis revealed reduced risks for alcohol consumption below 2 units/day, masking increased risks for 2 or more units/day.

Lower Aorto-Iliac Bifurcation Position and Incident Cardiovascular Disease: A Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

With increasing age, a downward shift of the aorto-iliac bifurcation relative to the lumbar spine occurs. A lower bifurcation position is an independent marker for adverse vascular aging and is associated with increased burden of cardiovascular disease (CVD) risk factors; however, the associations between lower bifurcation position and CVD events remain unknown.

METHODS

Abdominal computed tomography scans were used to measure the aorto-iliac bifurcation distance (AIBD, distance from the aorto-iliac bifurcation to the L5/S1 disc space). Cox proportional hazard analysis was used to determine the independent hazard of a lower bifurcation position (smaller AIBD) for incident coronary heart disease (CHD, defined as myocardial infarction, resuscitated cardiac arrest, or sudden cardiac death), CVD (CHD plus stroke or stroke death), and all-cause mortality (ACM).

RESULTS

In the 1,711 study participants (51% male), the mean AIBD was 26 ± 15 mm. After a median follow-up of 10 years, 63 (3.7%) developed CHD, 100 (5.8%) developed CVD, and 129 (7.5%) were deceased. Compared to the 4^th quartile of AIBD (highest bifurcation position), participants in the 1^st quartile (lowest bifurcation position) had increased risk for CHD (hazard ratio (HR) = 1.5, 95% confidence interval (CI): 0.8-3.0, P = 0.2), CVD (HR = 1.8, 95% CI: 0.9-2.7, P = 0.1), and ACM (HR = 2.2, 95% CI: 1.3-3.6, P = 0.01). After adjustments for CVD risk factors, the HR for ACM was no longer significant.

CONCLUSION

Despite being an independent marker for adverse vascular changes in the aorta, a lower aorto-iliac bifurcation position was not independently associated with future CVD events. The opposing effects of atherosclerosis and stiffness in the aorta may, in part, explain our null findings.

Glycated Hemoglobin Is Associated With the Growth Rate of Abdominal Aortic Aneurysms: A Substudy From the VIVA (Viborg Vascular) Randomized Screening Trial

OBJECTIVE

An inverse association between abdominal aortic aneurysms (AAAs) and diabetes mellitus exists; however, the cause remains unknown. This study aimed to evaluate whether the degree of glycemia is associated with aneurysm growth.

APPROACH AND RESULTS

The study was based on VIVA trial (Viborg Vascular), the randomized clinically controlled screening trial for abdominal aortic aneurysm in men aged 65 to 74 years in the Central Denmark Region. The screening included measurement of the abdominal aorta by ultrasound, analysis of glycated hemoglobin (HbA1c), and follow-up for ≤5 years for aneurysms <5 cm. Analyses were conducted using mixed-effect models. At baseline, VIVA screening identified 619 individuals (3.3%) with abdominal aortic aneurysms. A total of 103 individuals were referred for vascular evaluation, and after removal of additional individuals who were lost to follow-up or had missing blood samples, we were left with 319 individuals. Sixty-one individuals (19.1%) had diabetes mellitus. The median growth rate was 1.7 versus 2.7 mm/y in individuals with and without diabetes mellitus, respectively (P<0.001). We found a significant inverse association between aneurysmal growth rate and HbA1c in the total study population (P=0.002). Both crude and adjusted analyses identified slower growth for the group with the highest HbA1c tertile compared with the lowest HbA1c tertile. After 3 years, the mean difference was 1.8 mm (confidence interval, 0.98-2.64). Similar significant differences were observed in subgroup analysis of individuals without self-reported diabetes mellitus.

CONCLUSIONS

We found an inverse association between the growth rate of abdominal aortic aneurysms and the level of HbA1c, indicating that long-lasting elevated blood sugar impairs aneurysmal progression in individuals with and without known diabetes mellitus.

Associations of Diabetes and Obesity with Risk of Abdominal Aortic Aneurysm in Men

Background. The associations of diabetes and obesity with the risk of abdominal aortic aneurysm (AAA) are inconclusive in previous studies. Subjects/Methods. We conducted prospective analysis in the Physicians' Health Study. Among 25,554 male physicians aged ≥ 50 years who reported no AAA at baseline, 471 reported a newly diagnosed AAA during a mean of 10.4 years' follow-up. Results. Compared with men who had baseline body mass index (BMI) < 25 kg/m², the multivariable hazard ratio (HR [95% CI]) of newly diagnosed AAA was 1.30 [1.06-1.59] for BMI 25-<30 kg/m² and 1.69 [1.24-2.30] for BMI ≥ 30 kg/m². The risk of diagnosed AAA was significantly higher by 6% with each unit increase in baseline BMI. This association was consistent regardless of the other known AAA risk factors and preexisting vascular diseases. Overall, baseline history of diabetes tended to be associated with a lower risk of diagnosed AAA (HR = 0.79 [0.57-1.11]); this association appeared to vary by follow-up time (HR = 1.56 and 0.63 during ≤ and >2 years' follow-up, resp.). Conclusion. In a large cohort of middle-aged and older men, obesity was associated with a higher risk, while history of diabetes tended to associate with a lower risk of diagnosed AAA, particularly over longer follow-up.

Lifetime Risk and Risk Factors for Abdominal Aortic Aneurysm in a 24-Year Prospective Study: The ARIC Study (Atherosclerosis Risk in Communities)

OBJECTIVE

Abdominal aortic aneurysm (AAA) is an important vascular disease in older adults, but data on lifetime risk of AAA are sparse. We examined lifetime risk of AAA in a community-based cohort and prospectively assessed the association between midlife cardiovascular risk factors and AAAs.

APPROACH AND RESULTS

In ARIC study (Atherosclerosis Risk in Communities), 15 792 participants were recruited at visit 1 in 1987 to 1989 and followed up through 2013. Longitudinal smoking status was defined using smoking behavior ascertained from visit 1 (1987-1989) to visit 4 (1996-1998). We followed up participants for incident, clinical AAAs using hospital discharge diagnoses, Medicare outpatient diagnoses, or death certificates through 2011 and identified 590 incident AAAs. An abdominal ultrasound was conducted in 2011 to 2013 in 5911 surviving participants, and 75 asymptomatic AAAs were identified. We estimated the lifetime risk of AAA from the index age 45 years through 85 years of age. At age 45, the lifetime risk for AAA was 5.6% (95% confidence interval, 4.8-6.1) and was higher in men (8.2%) and current smokers (10.5%). Smokers who quit smoking between visit 1 and visit 4 had a 29% lower AAA lifetime risk compared with continuous smokers but had a higher risk than pre-visit 1 quitters. The lifetime risk of rupture or medical intervention was 1.6% (95% confidence interval, 1.2-1.8). Smoking, white race, male sex, greater height, and greater low-density lipoprotein or total cholesterol were associated with an increased risk of clinical AAA and asymptomatic AAA.

CONCLUSIONS

At least 1 in 9 middle-aged current smokers developed AAA in their lifetime. Smoking cessation reduced the lifetime risk of AAA.

Chronic Kidney Disease Is Positively and Diabetes Mellitus Is Negatively Associated with Abdominal Aortic Aneurysm

BACKGROUND AND AIMS

Chronic kidney disease (CKD) and diabetes mellitus (DM) are considered as risk factors for cardiovascular diseases. The purpose of this study was to clarify the relationship of CKD and DM with the presence of abdominal aortic aneurysm (AAA).

METHODS

We enrolled 261 patients with AAA (AAA+) and age-and-sex matched 261 patients without AAA (AAA-) at two hospitals between 2008 and 2014, and examined the association between the risk factors and the presence of AAA. Furthermore, in order to investigate the prevalence of AAA in each group, we enrolled 1126 patients with CKD and 400 patients with DM.

RESULTS

The presence of CKD in patients with AAA+ was significantly higher than that in patients with AAA- (AAA+; 65%, AAA-; 52%, P = 0.004). The presence of DM in patients with AAA+ was significantly lower than that in patients with AAA- (AAA+; 17%, AAA-; 35%, P < 0.001). A multivariate logistic regression analysis demonstrated that hypertension, ischemic heart disease and CKD were independent determinants, whereas, DM was a negatively independent determinant, for the presence of AAA. The prevalence of AAA in patients with CKD 65 years old and above was 5.1%, whereas, that in patients with DM 65 years old and above was only 0.6%.

CONCLUSION

CKD is a positively associated with the presence of AAA. In contrast, DM is a negatively associated with the presence of AAA in Japanese population.

Monocyte count-to-high-density lipoprotein-cholesterol ratio is associated with abdominal aortic aneurysm size

AIM

To determine the association of monocyte count-to-high-density lipoprotein (HDL)-cholesterol ratio, a recently emerged inflammatory marker, with abdominal aortic aneurysm (AAA) size.

PATIENTS & METHODS

A total of 120 asymptomatic AAA subjects (99 male, mean age: 67.1 ± 10.2 years) were enrolled into the study. All data were compared between patients with low and high admission monocyte/HDL ratio. Multivariate linear regression analysis was performed to study the relationship between different variables and AAA size.

RESULTS

Compared to patients with below-median monocyte/HDL ratio, aneurysm diameter was significantly higher in above-median monocyte/HDL ratio group (54.3 ± 10.6 mm vs 62.0 ± 12.4 mm, p < 0.001, respectively). Hypertension, coronary artery disease, monocyte/HDL ratio and C-reactive protein were independently associated with AAA diameter.

CONCLUSION

Monocyte/HDL ratio is independently associated with AAA size.

Association between use of oral-antidiabetic drugs and the risk of aortic aneurysm: a nested case-control analysis

Background

Pleiotropic effects on cardiovascular protection have been suggested in several oral antidiabetic drugs (OAD). The impacts of OADs on aortic aneurysm (AA) growth have been found in animal studies, but the evidence of their beneficial effects for AA protection in human are lacking. We investigated the relationship between OAD therapy and the risk of developing AA.

Methods

We conducted a nested case–control analysis using the database extracted from Taiwan’s National Health Insurance Research Database. The database consists of 1.2 million diabetic patients representing the majority of the type 2 diabetes population in Taiwan from 2000 to 2013. Cases were identified as those with either inpatient or outpatient diagnosis code of AA. One control was selected for each case matching on duration of follow-up, age, sex, urbanization, monthly income, severity of diabetes, and risk factor for AA. We identified variable classes of OADs, including metformin, sulfonylureas, thiazolidinedione (TZD), alpha-glucosidase inhibitors, meglitinide, dipeptidyl peptidase-4 (DPP-4) inhibitors prior to the development of AA.

Results

A total of 4468 cases diagnosed with AA and 4468 matched controls were identified. Metformin use, sulfonylurea use, and TZD were associated with lower risk of developing AA, odds ratio [OR] 0.72 (95 % confidence interval [CI] 0.64–0.80), 0.82 (95 % CI 0.74–0.92), and 0.82 (95 % CI 0.69–0.98), respectively. The effects of metformin and sulfonylurea on AA were dose responsive. Neither alpha-glucosidase inhibitors (OR 0.95; 95 % CI 0.81–1.11) nor DPP-4 inhibitors (OR 0.85; 95 % CI 0.68–1.07) was significantly associated with AA events.

Conclusions

Metformin, sulfonylurea, and TZD treated patients were associated with lower risks of AA development, but not DPP-4 inhibitors or alpha-glucosidase inhibitor. The protective effects of hypoglycemic agents are further confirmed by the dose responsive relations in metformin and sulfonylurea groups.