Matrix biology of abdominal aortic aneurysms in diabetes: mechanisms underlying the negative association

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

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pathogenesis and management of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) causes ∼170 000 deaths annually worldwide. Most guidelines recommend asymptomatic small AAAs (30 to <50 mm in women; 30 to <55 mm in men) are monitored by imaging and large asymptomatic, symptomatic, and ruptured AAAs are considered for surgical repair. Advances in AAA repair techniques have occurred, but a remaining priority is therapies to limit AAA growth and rupture. This review outlines research on AAA pathogenesis and therapies to limit AAA growth. Genome-wide association studies have identified novel drug targets, e.g. interleukin-6 blockade. Mendelian randomization analyses suggest that treatments to reduce low-density lipoprotein cholesterol such as proprotein convertase subtilisin/kexin type 9 inhibitors and smoking reduction or cessation are also treatment targets. Thirteen placebo-controlled randomized trials have tested whether a range of antibiotics, blood pressure-lowering drugs, a mast cell stabilizer, an anti-platelet drug, or fenofibrate slow AAA growth. None of these trials have shown convincing evidence of drug efficacy and have been limited by small sample sizes, limited drug adherence, poor participant retention, and over-optimistic AAA growth reduction targets. Data from some large observational cohorts suggest that blood pressure reduction, particularly by angiotensin-converting enzyme inhibitors, could limit aneurysm rupture, but this has not been evaluated in randomized trials. Some observational studies suggest metformin may limit AAA growth, and this is currently being tested in randomized trials. In conclusion, no drug therapy has been shown to convincingly limit AAA growth in randomized controlled trials. Further large prospective studies on other targets are needed.

Clinical features and prognosis of patients with and without diabetes mellitus undergoing endovascular aortic aneurysm repair

BACKGROUND

This study aimed to compare the clinical features and prognoses of patients with and without diabetes mellitus (DM) who underwent endovascular repair for aortic aneurysm (AA).

METHODS

We analyzed the clinical database of a prospective multicenter study, registering 929 patients who underwent their first endovascular AA repair in Japan between January 2016 and June 2018. The baseline characteristics and prognoses (including all-cause mortality and cardiovascular events) after repair were compared between the DM and non-DM groups. Prognoses were also compared between the groups after propensity score matching.

RESULTS

In total, 226 patients (24.3%) had DM. Compared with non-DM patients, DM patients had higher pack-years of smoking (P = 0.011), higher body mass index (P = 0.009), lower high-density lipoprotein cholesterol levels (P = 0.038), higher triglyceride levels (P = 0.025), and lower left ventricular ejection fraction (P = 0.005). Meanwhile, the low-density lipoprotein cholesterol and blood pressure levels showed no significant intergroup difference (all P > 0.05). DM patients had a higher prevalence of myocardial infarction (P = 0.016), history of coronary revascularization (P = 0.015), and lower extremity artery disease (P = 0.019). Lesion characteristics and procedures were similar between the groups (all P > 0.05). DM patients had a higher risk of all-cause mortality and cardiovascular events than non-DM patients (both P < 0.001). Subsequent propensity score matching also demonstrated that DM patients had a significantly lower rate of overall survival (P = 0.001) and freedom from cardiovascular events (P = 0.010). The Kaplan-Meier estimates at 1 year for the overall survival were 85.6% (95% confidence interval [CI], 80.9% to 90.5%) and 94.3% (95% CI, 91.7% to 97.0%) for patients with and without DM, respectively. The corresponding estimates for freedom from cardiovascular events were 79.8% (95% CI, 74.5% to 85.5%) and 87.7% (95% CI, 84.2% to 91.3%), respectively.

CONCLUSIONS

Among patients undergoing endovascular AA repair, those with DM had more cardiovascular risk factors. DM patients had a higher incidence rate of all-cause mortality and cardiovascular events. Matching analysis indicated that DM per se would be a risk factor for poor prognoses after AA repair.

Exploring the Correlation and Protective Role of Diabetes Mellitus in Aortic Aneurysm Disease

Introduction: Diabetes mellitus is recognised as a significant risk factor for cardiovascular and peripheral vascular disease, as the abnormal metabolic state increases the risk for atherosclerosis, occlusive arterial disease and vascular dysfunction. There have been reports of potential association across the literature that illustrates a link between diabetes mellitus and aortic aneurysm, with the former having a protective role on the development of the latter.

Methods: A thorough literature search was performed through electronic databases, to provide a comprehensive review of the study's reporting on the association of diabetes mellitus and aortic aneurysm, discussing the mechanisms that have been reported; furthemore, we reviewed the reports of the impact of oral hypoglycameic agents on aortic aneurysms.

Results: Various proposed mechanisms are involved in this protective process including endothelial dysfunction, chronic hyperglycemia and insulin resistance. The evidence suggests a negative association between these disease process, with prevelance of diabetes mellitus resulting in lower rates of aortic aneurysm, via its protective mechanistic action. The increase in advanced glycation end products, increased arterial stiffness and vascular remodelling seen in diabetes, was found to have a profound impact on aneurysm development, its slow progression and lower rupture rate in these individuals. This review has also highlighted the role of oral hypoglycaemic agents having a protective effect against AA disease.

Conclusion: A decrease in development, progression and mortality from aortic aneurysms as well as reduced rates of dissection, have been observed in those with diabetes. This review has provided a comprehensive insight on the effect of diabetes and its physiological processes, and elements of its con-committant treatment, having a protective role against these aortic diseases.

Diabetes is not protective against the formation of unruptured cerebral aneurysm

OBJECTIVES

Diabetes appears to decrease the risk of subarachnoid hemorrhage. However, it is not clear whether diabetes decreases the risk of aneurysm formation. The aim of our study to evaluate the risk of unruptured cerebral aneurysm in patients with diabetes mellitus.

METHODS

We used data from participants who underwent brain magnetic resonance angiography (MRA) and laboratory tests at the Healthcare System Gangnam Center of Seoul National University Hospital between January 2010 and December 2013. From the 17,368 participants who underwent brain MRA, we analyzed 16,337 subjects whose diabetes status could be identified.

RESULTS

The number of participants with diabetes was 2299 (14.1%). The proportion of participants with cerebral aneurysms was 2.3% in the diabetic group and 2.7% in the non-diabetic group, which was not significantly different (P = 0.225). There were no significant differences in the size, location, and multiplicity of aneurysms between the diabetes and control groups. In multivariate logistic regression, older age showed significant risk effects on cerebral aneurysms, but female sex, hypertension, diabetes, obesity, and smoking did not show significant risk effects.

CONCLUSION

In this study, diabetes did not affect the risk of cerebral aneurysm formation. In addition, neither smoking, nor hypertension was a significant risk factor for unruptured cerebral aneurysms. The lack of association between cerebral aneurysm and the traditional risk factors for subarachnoid hemorrhage requires further study. Risk factors for cerebral aneurysm development and those for cerebral aneurysm rupture may be different.

Systematic review and Meta-Analysis of Mendelian randomisation analyses of Abdominal aortic aneurysms

INTRODUCTION

Mendelian randomisation (MR) has been suggested to be able to overcome biases of observational studies, but no meta-analysis is available on MR studies on abdominal aortic aneurysm (AAA). This systematic review and Meta-analysis examined the evidence of causal risk factors for AAA identified in MR studies.

METHODS

Publicly available databases were systematically searched for MR studies that reported any causal risk factors for AAA diagnosis. Meta-analyses were performed using random effect models and reported as odds ratio (OR) and 95% confidence intervals (CI). Study quality was assessed using a modified version of Strengthening the Reporting of Mendelian Randomisation Studies (STROBE-MR) guidelines.

RESULTS

Sixteen MR studies involving 34,050 patients with AAA and 2,205,894 controls were included. Meta-analyses suggested that one standard deviation increase in high density lipoprotein (HDL) significantly reduced (OR: 0.66, 95% CI: 0.61, 0.72) and one standard deviation increase in low density lipoprotein (LDL) significantly increased the risk (OR: 1.68, 95%, CI: 1.55, 1.82) of AAA. One standard deviation increase in triglycerides did not significantly increase the risk of AAA (OR: 1.21, 95% CI: 0.86, 1.71). Quality assessment suggested that ten and five studies were of low and moderate risk of bias respectively, with one study considered as high risk of bias.

CONCLUSION

This meta-analysis suggests LDL and HDL are positive and negative casual risk factors for AAA.

Aberrant Mitochondrial Dynamics: An Emerging Pathogenic Driver of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is defined as a progressive segmental dilation of the abdominal aorta and is associated with high mortality. The characterized features of AAA indicate several underlying mechanisms of AAA formation and progression, including reactive oxygen species production, inflammation, and atherosclerosis. Mitochondrial functions are critical for determining cell fate, and mitochondrial dynamics, especially selective mitochondrial autophagy, which is termed as mitophagy, has emerged as an important player in the pathogenesis of several cardiovascular diseases. The PARKIN/PARIS/PGC1α pathway is associated with AAA formation and has been proposed to play a role in mitochondrial dynamics mediated by the PINK/PARKIN pathway in the pathogenesis underlying AAA. This review is aimed at deepening our understanding of AAA formation and progression, which is vital for the development of potential medical therapies for AAA.

Abdominal aortic aneurysms and abdominal wall hernias - a systematic review and meta-analysis

Background: Abdominal wall hernias (AWHs) share common epidemiological characteristics with abdominal aortic aneurysms (AAAs), typically presenting in male population and older ages. Prior reports have associated those two disease entities. Our objective was to perform a systematic review and meta-analysis and examine whether AAA rates are higher among patients with AWH vs controls and whether the incidence of AWH was higher among patients with AAA vs patients without AAA. Methods: We performed a systematic review and meta-analysis according to the PRISMA guidelines. The Medline database was searched up to July 31, 2020. A random effects meta-analysis was performed. Results: In total, 17 articles and 738,972 participants were included in the systematic review, while 107,578 patients were eligible for the meta-analysis. Among four studies investigating the incidence of AAA in patients with hernias, AAA was more common in patients with hernias, compared to patients without hernias. [OR: 2.53, 95% CI: 1.24-5.16, I²=81.6%]. Among thirteen studies that compared patients with known AAA vs no AAA, the incidence of hernias was higher in patients with AAA, compared with patients without AAA [OR: 2.27, 95% CI: 1.66-3.09, I²=84.6%]. Conclusions: Our study findings indicate that a strong association between AWH and AAA exists. AWHs could therefore be used as an additional selection criterion for screening patients for AAA, apart from age, gender, family history and smoking.

Association Between Cardiovascular Risk Factors and the Diameter of the Thoracic Aorta in an Asymptomatic Population in the Central Appalachian Region

BACKGROUND

Effects of cardiovascular (CV) risk factors on the diameter of the thoracic aorta have not been fully studied. This study examined the associations between CV risk factors and diameter of thoracic aorta.

MATERIALS AND METHODS

Study population comprised of 1273 asymptomatic adults aged ≥18 years from Central Appalachia region of the United States who participated in a coronary artery screening between January 2014 and December 2016. Descriptive statistics and multiple linear regression analyses were performed to examine associations between multiple CV risk factors and diameters of the thoracic aorta.

RESULTS

Mean (±SD) age of participants was 57.9±9.7 years; that of body mass index (BMI) was 29.4±5.9. The mean aortic sinus, ascending aorta, and descending aorta diameter were 34.1±4.4 mm, 33.8±4.4 mm, and 26.0±3.6 mm, respectively. Increasing age, being male, and having a higher BMI were associated with wider aortic sinus, ascending aorta, and descending aorta diameters. Hypertension (p < 0.05) and obesity (p < 0.0001) were significantly associated with wider diameter for all measured aortic diameters. Participants with diabetes had wider descending aorta compared to those without (26.6±3.9 mm vs. 25.9±3.5 mm, P = 0.012). Participants who had ever smoked a cigarette had significantly wider descending aorta diameter compared to never smokers (26.3±3.6 mm vs. 25.9±3.5 mm, p = 0.031).

CONCLUSIONS

The study results suggest that decreasing BMI and management of CV risk factors such as hypertension and modifying behavioral risk factors such as smoking are likely to be emphasized in order to decrease the rate of aortic dilatation and subsequent aortic dissection, if aortic dilatation is detected during a CT scan.

Diabetes Mellitus and Noncardiac Atherosclerotic Vascular Disease-Pathogenesis and Pharmacological Treatment Options

Diabetes mellitus (DM) is also a cause of cardiovascular (CV) disease (CVD). Addressing the atherosclerotic CVD (ASCVD) burden in DM should reduce premature death and improve quality of life. Diabetes mellitus-associated ASCVD can lead to complications in all vascular beds (carotids as well as coronary, lower extremity, and renal arteries). This narrative review considers the diagnosis and pharmacological treatment of noncardiac atherosclerotic vascular disease (mainly in patients with DM). Based on current knowledge and the fact that modern DM treatment guidelines are based on CV outcome trials, it should be noted that patients with noncardiac CVD may not have the same benefits from certain drugs compared with patients who predominantly have cardiac complications. This leads to the conclusion that in the future, consideration should be given to conducting well-designed trials that will answer which pharmacological treatment modalities will be of greatest benefit to patients with noncardiac ASCVD.

Abdominal aortic aneurysm: a review on the role of oral antidiabetic drugs

INTRODUCTION

A paradoxical negative association between diabetes mellitus and abdominal aortic aneurysm (AAA) prevalence and growth is established. However, so far is not possible to determine whether this protection comes from the disease itself or the medication for Diabetes. The aim of this manuscript is to review the association between oral antidiabetic drugs and AAA incidence and growth.

EVIDENCE ACQUISITION

A search was conducted on PubMed and Scopus databases until December 2019 to identify publications reporting on the association between oral antidiabetic drugs (biguanides/metformin, sulfonylureas(SU), thiazolidinediones(TZD), dipeptidyl-peptidase 4(DPP-4) inhibitors, glucagon-like peptide 1(GLP-1) agonists, sodium-glucose transporter protein-2(SGLT2) inhibitors) and the outcomes AAA incidence and growth. Only data from human studies were considered, with a minimum of 3 months follow-up.

EVIDENCE SYNTHESIS

Six studies enrolling 25,810 patients were included: one reporting on the AAA risk and five reporting on AAA growth. Metformin prescription was associated with a 28% reduction in AAA occurrence, while SU and TZD were associated with a 18% decrease in AAA risk. Regarding AAA enlargement, results were concordant for a slower expansion rate associated with metformin, with a decrease ranging from -0.30 mm/y to -1.30 mm/y, but not consistent for other antidiabetic drugs.

CONCLUSIONS

Metformin seems to be associated with a decrease in AAA risk and enlargement rate. Evidence for the other classes is lacking. Studies evaluating the association between oral antidiabetic drugs and AAA progression, independently of the diabetic status, are needed.

Prevalence of Intracranial Aneurysms in Patients With Systemic Vessel Aneurysms: A Nationwide Cohort Study

Background and Purpose- Most aneurysms are a focal manifestation of a systemic condition. Some reports have suggested genetic and environmental factors may play a role in pathogenesis. The aim of the present study was to evaluate the prevalence of intracranial aneurysms (IA) in a large cohort of patients with other systemic vessel aneurysms and dissections (OVAD) and identify potential risk factors for IA in this population. Methods- We defined OVAD as systemic vessel aneurysms, excluding aortic dissections and aneurysms. A cohort of 1.1 million patients was extracted from the population-based cohort from the Korea National Health Insurance Service, which holds almost all medical data including diagnostic codes, procedures, and personal information. Using χ² or Fisher exact test, the prevalence of the IA concerning OVAD status was analyzed. Results- In OVAD individuals, 25.7% (261/1017) of patients had been concurrently diagnosed with IA. The odds ratios for having concurrent IA in patients with OVAD were 56.31 (95% CI, 48.821-64.949; P=0.000). OVAD patients with dyslipidemia were >7× likely to be affected by IA (adjusted odds ratio, 7.7 [95% CI, 6.59-9.01]; P=0.000). Hypertension, diabetes mellitus, old age (>60 years), and male sex had increased odds for having concurrent IA by 5.89, 3.48, 1.83, and 1.35, respectively. Subgroup analysis with socioeconomic or disability revealed that the prevalence of IA was significantly higher in all groups. Uncertainty regarding the temporal sequence of onset and lack of detail on disease severity and subtype prevented more conclusive results. Conclusions- Patients with OVAD have a higher prevalence of IA than control groups. Therefore, we may approach aneurysms as systemic disease, and further investigations about their pathophysiology must follow.

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.

Diabetes mellitus and abdominal aortic aneurysms: A review of the mechanisms underlying the negative relationship

INTRODUCTION

Diabetes mellitus appears to be negatively associated with abdominal aortic aneurysm; however, the mechanisms underlying this relationship remain poorly understood. The aim of this article is to provide a comprehensive review of the currently understood biological pathways underlying this relationship.

METHODS

A review of the literature ('diabetes' OR 'hyperglycaemia' AND 'aneurysm') was performed and relevant studies grouped into biological pathways.

RESULTS

This review identified a number of biological pathways through which diabetes mellitus may limit the presence, growth and rupture of abdominal aortic aneurysms. These include those influencing extracellular matrix volume, extracellular matrix glycation, the formation of advanced glycation end-products, inflammation, oxidative stress and intraluminal thrombus biology. In addition, there is an increasing evidence to suggest that the medications used to treat diabetes can also limit the development and progression of abdominal aortic aneurysms.

CONCLUSION

The negative association between diabetes and abdominal aortic aneurysm is robust. Future studies should attempt to target the pathways identified in this review to develop novel therapeutic agents aimed at slowing or even halting aneurysm progression.

Diabetes, Incretin Therapy and Thoracic Aortic Aneurysm - What Does the Evidence Show?

Epidemiological evidence supports a reduced prevalence of Thoracic Aortic Aneurysm (TAA) and Abdominal Aortic Aneurysm (AAA) in patients with Diabetes (DM). The mechanisms underlying this negative association are unknown. Some studies support that hyperglycemia has effects on the Extracellular Matrix (ECM), resulting in collagen cross-links and altered proteolytic activity, which ultimately counteracts aneurysm formation. However, recent experimental research indicates that incretin- based anti-diabetic therapy and Glucagon-Like Peptide-1 (GLP-1) may reduce the formation of TAA. GLP-1 is a peptide hormone, released from intestinal L-cells in response to hormonal, neural and nutrient stimuli. In addition to potentiation of meal-stimulated insulin secretion, GLP-1 signaling exerts numerous pleiotropic effects on various tissues, including protective effects on the myocardium and vascular endothelium. Recent studies also report protective effects of GLP-1 based therapy on the formation of aneurysms in animal models and direct effects of GLP-1 signaling on the molecular mechanisms suggested to influence TAA formation, including inflammation, proteolytic activity and collagen composition. In this narrative review, we present the available evidence for effects of GLP-1 on experimental aneurysm development and discuss the potential role of GLP-1 in aneurysm formation based on available data from pre-clinical and clinical studies.

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?

Diabetes Reduces Severity of Aortic Aneurysms Depending on the Presence of Cell Division Autoantigen 1 (CDA1)

Diabetes is a negative risk factor for aortic aneurysm, but the underlying explanation for this phenomenon is unknown. We have previously demonstrated that cell division autoantigen 1 (CDA1), which enhances transforming growth factor-β signaling, is upregulated in diabetes. We hypothesized that CDA1 plays a key role in conferring the protective effect of diabetes against aortic aneurysms. Male wild-type, CDA1 knockout (KO), apolipoprotein E (ApoE) KO, and CDA1/ApoE double-KO (dKO) mice were rendered diabetic. Whereas aneurysms were not observed in diabetic ApoE KO and wild-type mice, 40% of diabetic dKO mice developed aortic aneurysms. These aneurysms were associated with attenuated aortic transforming growth factor-β signaling, reduced expression of various collagens, and increased aortic macrophage infiltration and matrix metalloproteinase 12 expression. In the well-characterized model of angiotensin II-induced aneurysm formation, concomitant diabetes reduced fatal aortic rupture and attenuated suprarenal aortic expansion, changes not seen in dKO mice. Furthermore, aortic CDA1 expression was downregulated ∼70% within biopsies from human abdominal aortic aneurysms. The identification that diabetes is associated with upregulation of vascular CDA1 and that CDA1 deletion in diabetic mice promotes aneurysm formation provides evidence that CDA1 plays a role in diabetes to reduce susceptibility to aneurysm formation.

Application of Metabolic Profiling to Abdominal Aortic Aneurysm Research

Abdominal aortic aneurysm (AAA) is a complex disease posing diagnostic and therapeutic challenges. Metabonomics may aid in the diagnosis of AAA, determination of individualized risk, discovery of therapeutic targets, and improve understanding of pathogenesis. A systematic review of the diversity and outcomes of existing AAA metabonomic research has been performed. Original research studies applying metabonomics to human aneurysmal disease are included. Seven relevant articles were identified: four studies were based on plasma/serum metabolite profiling, and three studies examined aneurysmal tissue. Aminomalonic acid, guanidinosuccinic acid, and glycerol emerge as potential plasma biomarkers of large aneurysm. Lipid profiling improves predictive models of aneurysm presence. Patterns of metabolite variation associated with AAA relate to carbohydrate and lipid metabolism. Perioperative perturbations in metabolites suggest differential systemic inflammatory responses to surgery, generating hypotheses for adjunctive perioperative therapy. Significant limitations include small study sizes, lack of correction for multiple testing false discovery rates, and single time-point sampling. Metabolic profiling carries the potential to identify biomarkers of AAA and elucidate pathways underlying aneurysmal disease. Statistically and methodologically robust studies are required for validation, addressing the hiatus in understanding mechanisms of aneurysm growth and developing effective treatment strategies.

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.

Epigenetics and Peripheral Artery Disease

The term epigenetics is usually used to describe inheritable changes in gene function which do not involve changes in the DNA sequence. These typically include non-coding RNAs, DNA methylation and histone modifications. Smoking and older age are recognised risk factors for peripheral artery diseases, such as occlusive lower limb artery disease and abdominal aortic aneurysm, and have been implicated in promoting epigenetic changes. This brief review describes studies that have associated epigenetic factors with peripheral artery diseases and investigations which have examined the effect of epigenetic modifications on the outcome of peripheral artery diseases in mouse models. Investigations have largely focused on microRNAs and have identified a number of circulating microRNAs associated with human peripheral artery diseases. Upregulating or antagonising a number of microRNAs has also been reported to limit aortic aneurysm development and hind limb ischemia in mouse models. The importance of DNA methylation and histone modifications in peripheral artery disease has been relatively little studied. Whether circulating microRNAs can be used to assist identification of patients with peripheral artery diseases and be modified in order to improve the outcome of peripheral artery disease will require further investigation.

Association of diabetes mellitus with presence, expansion, and rupture of abdominal aortic aneurysm: "Curiouser and curiouser!" cried ALICE

Both coronary artery and peripheral artery disease are representative atherosclerotic diseases that are positively associated with presence of abdominal aortic aneurysm (AAA). Diabetes mellitus, which is one of major risk factors of coronary artery and peripheral artery diseases, however, has been curiously suggested to be negatively associated with AAA, despite the positive associations of coronary artery and peripheral artery diseases with presence of AAA. In the present article, we overviewed epidemiologic evidence (meta-analyses) regarding the associations of diabetes mellitus with presence, expansion, and rupture of AAA through a systematic literature search. Our exhaustive search identified seven meta-analyses. Main results of almost all meta-analyses (except for the two earliest ones) apparently found that diabetes mellitus is negatively associated with presence, expansion, and rupture of AAA.

Abdominal aortic aneurysms and diabetes mellitus

There is accumulating evidence that risk profiles differ between coronary artery disease and abdominal aortic aneurysms (AAAs). However, diabetes mellitus (DM) appears to be negatively associated with AAA formation. The underlying mechanisms for this negative relationship are far from defined, but may include: increased arterial wall matrix formation via advanced glycation end products; suppression of plasmin and reduction of levels and activity of matrix metalloproteinases (MMP)-2 and 9; diminished aortic wall macrophage infiltration, elastolysis and neovascularization. In addition, the effect of pharmacological agents used for the treatment of patients with DM on AAA formation has been studied with rather controversial results. Statins, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, fenofibrate, antibiotics and some hypoglycemic agents are beginning to be appreciated for a potential modest protection from AAAs, but further studies are needed.

Diabetes and Abdominal Aortic Aneurysm Growth

We performed a systematic literature search and a meta-analysis to assess the association between diabetes mellitus (DM) and abdominal aortic aneurysm (AAA) growth. Databases including MEDLINE and EMBASE were searched through June 2015 using PubMed and OVID. For each study, data regarding AAA growth rates in both the DM and the non-DM groups were used to generate standardized mean differences (SMDs) and 95% confidence intervals (CIs). Our search identified 19 relevant studies including data on 9777 patients with AAA. Pooled analyses demonstrated a statistically significant slower growth rates in DM patients than in non-DM patients (unadjusted SMD, −0.32; 95% CI, −0.40 to −0.24; P < .00001; adjusted SMD, −0.29; 95% CI, −0.417 to −0.18; P < .00001). Despite possible publication bias in favor of DM based on funnel plot asymmetry, even adjustment of the asymmetry did not alter the beneficial effect of DM. In conclusion, on the basis of a meta-analysis of data on a total of 9777 patients (19 studies) identified through a systematic literature search, we confirmed the association of DM with slower growth rates of AAA.

MicroRNAs: Novel Players in Aortic Aneurysm

An aortic aneurysm (AA) is a common disease with potentially life-threatening complications. Despite significant improvements in the diagnosis and treatment of AA, the associated morbidity and mortality remain high. MicroRNAs (miRNAs, miR) are small noncoding ribonucleic acids that negatively regulate gene expression at the posttranscriptional level by inhibiting mRNA translation or promoting mRNA degradation. miRNAs are recently reported to be critical modulators for vascular cell functions such as cell migration, contraction, differentiation, proliferation, and apoptosis. Increasing evidences suggest crucial roles of miRNAs in the pathogenesis and progression of cardiovascular diseases such as coronary artery disease, heart failure, arterial hypertension, and cardiac arrhythmias. Recently, some miRNAs, such as miR-24, miR-155, miR-205, miR-712, miR-21, miR-26a, miR-143/145, miR-29, and miR-195, have been demonstrated to be differentially expressed in the diseased aortic tissues and strongly associated with the development of AA. In the present paper, we reviewed the recent available literature regarding the role of miRNAs in the pathogenesis of AA. Moreover, we discuss the potential use of miRNAs as diagnostic and prognostic biomarkers and novel targets for development of effective therapeutic strategies for AA.

Network wiring of pleiotropic kinases yields insight into protective role of diabetes on aneurysm

Recent studies suggest a protective role of diabetes in the development of aneurysm, but the biological mechanisms behind this are still unknown. This type of association is not present in the case of diabetes and atherosclerosis despite similar risk factors for aneurysm and atherosclerosis. We postulate the existence of genes that disrupt the pathways needed for the onset of aneurysm in the presence of diabetes. Motivated by the significance of genetic interactions in understanding disease-disease associations, we tackle this problem by integrating protein-protein interaction and genetic interaction data, i.e., we examine the biological pathways related to the three diseases that contain genes involved in the following genetic interactions: one gene in a genetic interaction is part of a diabetes pathway, the other gene is part of an aneurysm, or an atherosclerosis pathway. We create a protein-protein interaction sub-network that contains disease pathways described above. We then use a "brokerage" measure - a topological measure that identifies proteins in this sub-network whose removal severely affects the interconnectedness of their neighbourhood, enabling such proteins to disrupt the pathway they are in. We identify a set of proteins with high brokerage values and find this set to be enriched in biological functions, including cell-matrix adhesion, which facilitates mechanisms that have already been suggested as possible causes of diabetes-aneurysm association. We further narrow down our set to 16 proteins that are involved in an aneurysm or an atherosclerosis pathway and are encoded by genes participating in genetic interactions with a gene in a diabetes pathway. This set is enriched in kinases and phosphorylation processes, with two pleiotropic kinases that are involved in both aneurysm and atherosclerosis pathways. Kinases can turn on or off proteins, explaining how functional changes of such proteins could result in the disruption of pathways. So if in an aneurysm-related pathway a gene is turned off, the onset of the disease could be prevented. However, mutations of pleiotropic genes could have effects only on one of the traits, which explains why pleiotropic kinases that are involved in both aneurysm and atherosclerosis pathways could disrupt aneurysm pathways explaining the reduced risk of aneurysm in diabetes patients, but not affect the atherosclerosis pathways.

Advanced complicated diabetes mellitus is associated with a reduced risk of thoracic and abdominal aortic aneurysm rupture: a population-based cohort study

BACKGROUND

Studies have associated diabetes mellitus (DM) with the reduced risk of abdominal aortic aneurysm and thoracic aortic aneurysm and dissection. We used the national insurance data of Taiwan to examine these correlations for an Asian population. The association was also evaluated by DM severity.

METHODS

We identified 160,391 patients with type 2 DM diagnosed from 1998 to 2008 and 646,710 comparison subjects without DM, frequency matched by diagnosis date, sex and age (mainly the elderly). The DM severity was partitioned into advanced and uncomplicated status according to DM-related comorbidities.

RESULTS

By the end of 2010, the overall pooled incidence rate of thoracic aortic aneurysm and abdominal aortic aneurysm was 15% lower in the type 2 DM cohort than in non-DM cohort, with an adjusted hazard ratio of 0.64 [95% confidence interval (CI) 0.56-0.74] in the multivariable Cox model. Patients with advanced type 2 DM were significantly associated with reduced thoracic aortic aneurysm rupture and abdominal aortic aneurysm without rupture, with adjusted hazard ratios of 0.50 (95% CI 0.35-0.71) and 0.53 (95% CI 0.40-0.69), respectively. Uncomplicated type 2 DM was also associated with reduced abdominal aortic aneurysm without rapture (aHR = 0.58, 95% CI 0.45-0.74).

CONCLUSIONS

Our results demonstrate that patients with diabetes in this Asian population have reduced prevalence of thoracic and abdominal aortic aneurysms. The observed paradoxical inverse relationship between severity of DM and aortic aneurysms is clear. Further research is required to investigate the underlying mechanisms for the reduced risk of aortic aneurysms associated with diabetes.

Common variation in PHACTR1 is associated with susceptibility to cervical artery dissection

Cervical artery dissection (CeAD), a mural hematoma in a carotid or vertebral artery, is a major cause of ischemic stroke in young adults although relatively uncommon in the general population (incidence of 2.6/100,000 per year). Minor cervical traumas, infection, migraine and hypertension are putative risk factors, and inverse associations with obesity and hypercholesterolemia are described. No confirmed genetic susceptibility factors have been identified using candidate gene approaches. We performed genome-wide association studies (GWAS) in 1,393 CeAD cases and 14,416 controls. The rs9349379[G] allele (PHACTR1) was associated with lower CeAD risk (odds ratio (OR) = 0.75, 95% confidence interval (CI) = 0.69-0.82; P = 4.46 × 10(-10)), with confirmation in independent follow-up samples (659 CeAD cases and 2,648 controls; P = 3.91 × 10(-3); combined P = 1.00 × 10(-11)). The rs9349379[G] allele was previously shown to be associated with lower risk of migraine and increased risk of myocardial infarction. Deciphering the mechanisms underlying this pleiotropy might provide important information on the biological underpinnings of these disabling conditions.

Association of impaired fasting glucose, diabetes and their management with the presentation and outcome of peripheral artery disease: a cohort study

Background

Pre-diabetes and untreated diabetes are common in patients with peripheral artery disease however their impact on outcome has not been evaluated. We examined the association of impaired fasting glucose, diabetes and their treatment with the presentation, mortality and requirement for intervention in peripheral artery disease patients.

Methods

We prospectively recruited 1637 patients with peripheral artery disease, measured fasting glucose, recorded medications for diabetes and categorised them by diabetes status. Patients were followed for a median of 1.7 years.

Results

At entry 22.7% patients were receiving treatment for type 2 diabetes by oral hypoglycaemics alone (18.1%) or insulin (4.6%). 9.2% patients had non-medicated diabetes. 28.1% of patients had impaired fasting glucose (5.6-6.9 mM). Patients with non-medicated diabetes had increased mortality and requirement for peripheral artery intervention (hazards ratio 1.62 and 1.31 respectively). Patients with diabetes prescribed insulin had increased mortality (hazard ratio 1.97). Patients with impaired fasting glucose or diabetes prescribed oral hypoglycaemics only had similar outcomes to patients with no diabetes.

Conclusions

Non-medicated diabetes is common in peripheral artery disease patients and associated with poor outcomes. Impaired fasting glucose is also common but does not increase intermediate term complications. Peripheral artery disease patients with diabetes requiring insulin are at high risk of intermediate term mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-014-0147-2) contains supplementary material, which is available to authorized users.

Pathophysiology and risk factors of cervical artery dissection: what have we learnt from large hospital-based cohorts?

PURPOSE OF REVIEW

Cervical artery dissection (CeAD) is a major cause of ischemic stroke in young and middle-aged adults, although relatively uncommon in the community. Recent large collaborative projects have provided new insights into mechanisms and risk factors of CeAD.

RECENT FINDINGS

Pathologic changes observed at the media-adventitia border in temporal arteries of CeAD patients suggest a predisposing arterial wall weakness. In large multicenter series of CeAD patients, compared to age-matched healthy controls and patients with an ischemic stroke of another cause, hypertension and migraine, especially without aura, were confirmed as risk factors for CeAD, in addition to cervical trauma and recent infection. Hypercholesterolemia and being overweight were shown to be inversely associated with CeAD. Differences in risk factor profile and structural features between carotid and vertebral dissection suggest that their pathophysiology may partly differ. An association of CeAD with fibromuscular dysplasia and reversible cerebral vasoconstriction syndrome was described. Genetic risk factors of CeAD are still poorly understood.

SUMMARY

Large cohorts of CeAD patients have refined our understanding of the pathophysiology and risk factors of CeAD, but the molecular mechanisms are still poorly understood. Ongoing high-throughput genetic projects will hopefully provide novel insight into the biological substrate of CeAD.

4-Hydroxynonenal impairs transforming growth factor-β1-induced elastin synthesis via epidermal growth factor receptor activation in human and murine fibroblasts

Elastin is a long-lived protein and a key component of connective tissues. The tissular elastin content decreases during chronological aging, and the mechanisms underlying its slow repair are not known. Lipid oxidation products that accumulate in aged tissues may generate protein dysfunction. We hypothesized that 4-hydroxynonenal (4-HNE), a highly reactive α,β-aldehydic product generated from polyunsaturated fatty acid peroxidation, could contribute to inhibiting elastin repair by antagonizing the elastogenic signaling of transforming growth factor-β1 (TGF-β1) in skin fibroblasts. We report that a low 4-HNE concentration (2µmol/L) inhibits the upregulation of tropoelastin expression stimulated by TGF-β1 in human and murine fibroblasts. The study of signaling pathways potentially involved in the regulation of elastin expression showed that 4-HNE did not block the phosphorylation of Smad3, an early step of TGF-β1 signaling, but inhibited the nuclear translocation of Smad2. Concomitantly, 4-HNE modified and stimulated the phosphorylation of the epidermal growth factor receptor (EGFR) and subsequently ERK1/2 activation, leading to the phosphorylation/stabilization of the Smad transcriptional corepressor TGIF, which antagonizes TGF-β1 signaling. Inhibitors of EGFR (AG1478) and MEK/ERK (PD98059), and EGFR-specific siRNAs, reversed the inhibitory effect of 4-HNE on TGF-β1-induced nuclear translocation of Smad2 and tropoelastin synthesis. In vivo studies on aortas from aged C57BL/6 mice showed that EGFR is modified by 4-HNE, in correlation with an increased 4-HNE-adduct accumulation and decreased elastin content. Altogether, these data suggest that 4-HNE inhibits the elastogenic activity of TGF-β1, by modifying and activating the EGFR/ERK/TGIF pathway, which may contribute to altering elastin repair in chronological aging and oxidative stress-associated aging processes.

Diabetes and abdominal aortic aneurysms

Epidemiologic evidence suggests that patients with diabetes may have a lower incidence of abdominal aortic aneurysm (AAA); however, the link between diabetes and AAA development and expansion is unclear. The aim of this review is to analyze updated evidence to better understand the impact of diabetes on prevalence, incidence, clinical outcome, and expansion rate of AAA. A systematic review of literature published in the last 20 years using the PubMed and Cochrane databases was undertaken. Studies reporting appropriate data were identified and a meta-analysis performed using the generic inverse variance method. Sixty-four studies were identified. Methodological quality was "fair" in 16 and "good" in 44 studies according to a formal assessment checklist (Newcastle-Ottawa). In 17 large population prevalence studies there was a significant inverse association between diabetes and AAA: pooled odds ratio (OR) 0.80; 95% confidence intervals (CI) 0.70-0.90 (p = .0009). An inverse association was also confirmed by pooled analysis of data from smaller prevalence studies on selected populations (OR 0.59; 95% CI 0.35-0.99; p = .05), while no significant results were provided by case-control studies. A significant lower pooled incidence of new AAA in diabetics was found over six prospective studies: OR 0.54; 95% CI 0.31-0.91; p = .03. Diabetic patients showed increased operative (30-day/in-hospital) mortality after AAA repair: pooled OR 1.26; 95% CI 1.10-1.44; p = .0008. The increased operative risk was more evident in studies with 30-day assessment. In the long-term, diabetics showed lower survival rates at 2-5 years, while there was general evidence of lower growth rates of small AAA in patients with diabetes compared to non-diabetics. There is currently evidence to support an inverse relationship between diabetes and AAA development and enlargement, even though fair methodological quality or unclear risk of bias in many available studies decreases the strength of the finding. At the same time, operative and long-term survival is lower in diabetic patients, suggesting increased cardiovascular burden. The higher mortality in diabetics raises the question as to whether AAA repair should be individualized in selected diabetic populations at higher AAA rupture risk.

Hospitalization rates and post-operative mortality for abdominal aortic aneurysm in Italy over the period 2000-2011

Background

Recent studies have reported declines in incidence, prevalence and mortality for abdominal aortic aneurysms (AAAs) in various countries, but evidence from Mediterranean countries is lacking. The aim of this study is to examine the trend of hospitalization and post-operative mortality rates for AAAs in Italy during the period 2000–2011, taking into account the introduction of endovascular aneurysm repair (EVAR) in 1990s.

Methods

This retrospective cohort study was carried out in Emilia-Romagna, an Italian region with 4.5 million inhabitants. A total of 19,673 patients hospitalized for AAAs between 2000 and 2011, were identified from the hospital discharge records (HDR) database. Hospitalization rates, percentage of OSR and EVAR and 30-day mortality rates were calculated for unruptured (uAAAs) and ruptured AAAs (rAAAs).

Results

Adjusted hospitalization rates decreased on average by 2.9% per year for uAAAs and 3.2% for rAAAs (p<0.001). The temporal trend of 30-day mortality rates remained stable for both groups. The percentage of EVAR for uAAAs increased significantly from 2006 to 2011 (42.7 versus 60.9% respectively, mean change of 3.9% per year, p<0.001). No significant difference in mortality was found between OSR and EVAR for uAAAs and rAAAs.

Conclusions

The incidence and trend of hospitalization rates for rAAAs and uAAAs decreased significantly in the last decade, while 30-day mortality rates in operated patients remained stable. OSR continued to be the most common surgery in rAAAs, although the gap between OSR and EVAR recently declined. The EVAR technique became the preferred surgery for uAAAs since 2008.

Abdominal aortic aneurysm: an often asymptomatic and fatal men's health issue

Men are more likely than women to develop an abdominal aortic aneurysm (AAA), a disease that is often asymptomatic and has up to a 90% risk of mortality if the aneurysm ruptures. What many men do not know is that an AAA can easily be identified through an ultrasound screening, and if the aneurysm is >5.5 cm, it can be surgically repaired to prevent a life-threatening rupture. Although current AAA screening recommendations focus on men between the ages of 65 and 75 years, who have ever smoked, recent evidence suggest many men of ages 50 to 80 years, regardless of smoking status, may also be at risk for developing an AAA. This article presents a comprehensive overview of AAA disease and summarizes current evidence-based diagnostic and treatment guidelines, the importance of educating men about this health issue, and the need for more widespread AAA ultrasound screening opportunities.

Discovery of a novel circulating biomarker in patients with abdominal aortic aneurysm: a pilot study using a proteomic approach

Abdominal aortic aneurysm (AAA) is a common condition with high mortality when ruptured. Most clinicians agree that small AAAs are best managed by ultrasonographic surveillance. However, it has been stated in recent reviews that a serum/plasma biomarker that predicts AAA rupture risk would be a powerful tool in stratifying patients with small AAA. Identification of such circulating biomarkers has been to date unsuccessful. In this study, we used a proteomic approach to find new, potential plasma AAA biomarker candidates. Prefractionated plasma samples were analyzed by two-dimensional differential in-gel electrophoresis to identify differentially expressed proteins between four patients with small AAA and four controls without aneurysm. Protein spots that differed significantly between patients and controls were selected and identified by mass spectrometry. Three protein spots had significantly different expression between patients and controls. The most interesting finding was that patients with small AAA had increased levels of the enzyme glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) compared with the controls without aneurysm. In conclusion, by using a proteomic approach, this pilot-study provides evidence of GPI-PLD as a novel potential plasma biomarker for AAA.

Socioeconomic position, comorbidity, and mortality in aortic aneurysms: a 13-year prospective cohort study

BACKGROUND

To evaluate factors associated with incidence and 3-year all-cause mortality in patients with aortic aneurysm (AA). The design is sex and age-stratified (60-79 and 80-90 years) prospective cohort. By using the population register, we constituted a cohort of all men and women born between 1900 and 1930 and living in Scania by 1991, and followed them for 13 years. Identification of AA was based on hospital discharge diagnosis obtained from the Swedish Patient Register or from the information on death certificates from the Cause of Death Register.

METHODS

We applied stepwise Cox regression and investigated both AA incidence (1991-2003) as well as 3-year survival after the first hospitalization for AA.

RESULTS

We found an inverse relation between AA incidence and previous hospitalization by diabetes mellitus in women (hazard ratio [HR]: 0.41; 95% confidence interval [CI]: 0.19-0.88) and in men (HR: 0.38; 95% CI: 0.24-0.61) aged 60-79 years. Three-year all-cause mortality after diagnosis of AA was 58.6% in women, 50.2% in men, 72.9% in octogenarians, and 43.7% for nonoctogenarians. Low income, chronic respiratory diseases, cerebrovascular diseases, dementia, systemic connective tissue disorders, renal failure, and malignant neoplasms were independent factors for mortality in 60-79-year-old men with AA.

CONCLUSIONS

Inferior socioeconomic position is associated with increased 3-year all-cause mortality in 60-79-year-old men with AA.

Neuropsychiatric symptoms in patients with aortic aneurysms

Background

Emerging evidence suggests that vascular disease confers vulnerability to a late-onset of depressive illness and the impairment of specific cognitive functions, most notably in the domains of memory storage and retrieval. Lower limb athero-thrombosis and abdominal aortic aneurysm (AAA) have both been previously associated with neuropsychiatric symptoms possibly due to associated intracerebral vascular disease or systemic inflammation, hence suggesting that these illnesses may be regarded as models to investigate the vascular genesis of neuropsychiatric symptoms. The aim of this study was to compare neuropsychiatric symptoms such as depression, anxiety and a variety of cognitive domains in patients who had symptoms of peripheral athero-thrombosis (intermittent claudication) and those who had an asymptomatic abdominal aortic aneurysm AAA.

Methodology/Principal Findings

In a cross-sectional study, 26 participants with either intermittent claudication or AAA were assessed using a detailed neuropsychiatric assessment battery for various cognitive domains and depression and anxiety symptoms (Hamilton Depression and Anxiety Scales). Student t test and linear regression analyses were applied to compare neuropsychiatric symptoms between patient groups. AAA participants showed greater levels of cognitive impairment in the domains of immediate and delayed memory as compared to patients who had intermittent claudication. Cognitive dysfunction was best predicted by increasing aortic diameter. CRP was positively related to AAA diameter, but not to cognitive function. AAA and aortic diameter in particular were associated with cognitive dysfunction in this study.

Conclusions/Significance

AAA patients are at a higher risk for cognitive impairment than intermittent claudication patients. Validation of this finding is required in a larger study, but if confirmed could suggest that systemic factors peculiar to AAA may impact on cognitive function.

Novel aspects of the pathogenesis of aneurysms of the abdominal aorta in humans

Aneurysm of the abdominal aorta (AAA) is a particular, specifically localized form of atherothrombosis, providing a unique human model of this disease. The pathogenesis of AAA is characterized by a breakdown of the extracellular matrix due to an excessive proteolytic activity, leading to potential arterial wall rupture. The roles of matrix metalloproteinases and plasmin generation in progression of AAA have been demonstrated both in animal models and in clinical studies. In the present review, we highlight recent studies addressing the role of the haemoglobin-rich, intraluminal thrombus and the adventitial response in the development of human AAA. The intraluminal thrombus exerts its pathogenic effect through platelet activation, fibrin formation, binding of plasminogen and its activators, and trapping of erythrocytes and neutrophils, leading to oxidative and proteolytic injury of the arterial wall. These events occur mainly at the intraluminal thrombus-circulating blood interface, and pathological mediators are conveyed outwards, where they promote matrix degradation of the arterial wall. In response, neo-angiogenesis, phagocytosis by mononuclear cells, and a shift from innate to adaptive immunity in the adventitia are observed. Abdominal aortic aneurysm thus represents an accessible spatiotemporal model of human atherothrombotic progression towards clinical events, the study of which should allow further understanding of its pathogenesis and the translation of pathogenic biological activities into diagnostic and therapeutic applications.

Diagnostic and therapeutic strategies for small abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) affect 5% of the population in developed countries and are characterized by progressive aortic dilatation with an unpredictable time course. This condition is more common in men than in women, and in smokers than in nonsmokers. If left untreated, AAA can result in aortic rupture and death. Pathologically, aortic extracellular matrix degradation, inflammation, and neovascularization are hallmarks of AAA. Diagnosis of AAA and subsequent surveillance utilize established aortic imaging methods, such as ultrasound, CT, and MRI. More-speculative diagnostic approaches include molecular and cellular imaging methods that interrogate the underlying pathological processes at work within the aneurysm. In this Review, we explore the current diagnostic and therapeutic strategies for the management of AAA. We also describe the diagnostic potential of new imaging techniques and therapeutic potential of new treatments for the management of small AAA.

Pathophysiology and epidemiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are found in up to 8% of men aged >65 years, yet usually remain asymptomatic until they rupture. Rupture of an AAA and its associated catastrophic physiological insult carries overall mortality in excess of 80%, and 2% of all deaths are AAA-related. Pathologically, AAAs are associated with inflammation, smooth muscle cell apoptosis, and matrix degradation. Once thought to be a consequence of advanced atherosclerosis, accruing evidence indicates that AAAs are a focal representation of a systemic disease of the vasculature. Risk factors for AAAs include increasing age, male sex, smoking, and low HDL-cholesterol levels. Familial associations exist and although susceptibility genes have been described on the basis of candidate-gene studies, robust genetic studies have failed to discover causative gene mutations. The surgical management of AAAs has been revolutionized by minimally invasive endovascular repair. Ongoing randomized trials will establish whether endovascular repair confers a survival advantage over open surgery for patients with a ruptured AAA. In many countries, centralization of vascular surgical services has largely been driven by the improved outcomes of elective aneurysm surgery in specialized centers, the widespread adoption of endovascular techniques, and the introduction of screening programs.