Risk factors associated with abdominal aortic aneurysm: a population-based study with historical and current data

A prospective longitudinal study of risk factors for abdominal aortic aneurysm

The aim of this study was to identify risk factors for abdominal aortic aneurysm (AAA) from the largest Welsh screening cohort to date. Patients were recruited from 1993 (to 2015) as part of the South East Wales AAA screening programme through general practitioners. Demographic data and risk factors were collected by means of a self-report questionnaire. Statistical tests were performed to determine whether associations could be observed between AAA and potential risk factors. Odds ratios (OR) were also calculated for each of the risk factors identified. A total of 6879 patients were included in the study. Two hundred and seventy-five patients (4.0%) presented with AAA, of which 16% were female and 84% were male. Patients with AAA were older than the (no AAA) control group (p < 0.0001). The following risk factors were identified for AAA: family history of AAA (p < 0.0001); history of vascular surgery (p < 0.0001), cerebrovascular accident (p < 0.0001), coronary heart disease (p < 0.0001), diabetes (p < 0.0001), medication (p = 0.0018), claudication (p < 0.0001), smoking history (p = 0.0001) and chronic obstructive pulmonary disorder (p = 0.0007). AAA is associated with classical vascular risk factors, in addition to other less-well-documented risk factors including previous vascular surgery. These findings have practical implications with the potential to improve future clinical screening of patients in order to reduce AAA mortality.

A Novel Method for the Rat Model of Abdominal Aortic Aneurysm Induced by Retroperitoneal Implantation of an Osmotic Pump System With Lipopolysaccharide

BACKGROUND

Few methods can cocurrently mimic the pathological characteristics and nature history of human abdominal aortic aneurysms (AAAs), especially for the exist of the self-healing tendency of rodents. This study tested a novel method for the AAA rat model induced by retroperitoneal implantation of an osmotic pump system with lipopolysaccharide (LPS) based on the hypothesis that chronic inflammation of perivascular adipose tissue directly influenced the development and progression of AAAs.

METHODS

20 male Sprague-Dawley rats (10-month-old) fed with the Paigen diet were randomly divided into 4 groups: the blank group ×2, the sham group ×4, the empty capsule group ×4, and the LPS capsule group ×10. The LPS capsule group received implantations of the ALZET® osmotic pump capsule with LPS (3.6 μg/day) parallel to the abdominal aorta through a retroperitoneal approach. Two weeks later, 6 rats were randomly selected from the LPS capsule group to form the anti-inflammatory group and received implantations of another osmotic pump capsule with interleukin (IL)-10 (75 ng/day) through the same approach. The changes in abdominal aortic diameter were observed by ultrasound every 2 weeks, and samples were harvested for histopathologic and immunohistochemical analysis 6 weeks later.

RESULTS

Within the 6 weeks after modeling, the LPS capsule group showed sustained and significant aortic dilatation (P < 0.01), while the anti-inflammatory group showed a rapid and obvious shrinkage 2 weeks after the IL-10 osmotic pump capsule implantation (P < 0.01). The LPS capsule group presented excellent pathological mimicking of human AAAs and showed severe medial degeneration with the least elastic content among the 5 groups at the end of the sixth week (P < 0.05). Notably, the anti-inflammatory group showed perfect medial preservation with the most elastic content (P < 0.05) and the highest elastin/collagen ratio (P < 0.01) at the end of the study. Matrix metalloproteinases (MMP) 2 and 9 and toll-like receptor 2 showed strong expression in the LPS capsule group at the end of the sixth week, which was significantly higher than that in the blank group and sham group. Interestingly, the anti-inflammatory group showed a slightly higher MMP9 expression than the LPS capsule group though there was no statistical difference between them.

CONCLUSIONS

This novel method for the rat AAA model induced by retroperitoneal implantation of an osmotic pump capsule with LPS can concurrently mimic the histological characteristics and natural history of human AAAs. Further studies were needed to improve the osmotic pump system.

Rivaroxaban in patients with abdominal aortic aneurysm and high-sensitivity C-reactive protein elevation (BANBOO): study protocol for a randomized, controlled trial

BACKGROUND

Abdominal aortic aneurysm (AAA) is a fatal disease due to the tendency to rupture. The drug treatment for small AAA without surgical indications has been controversial. Previous studies showed that high-sensitivity C-reactive protein (hs-CRP) had become a potential biomarker of the disease, and the anti-inflammatory effect of rivaroxaban for AAA had been well established. Thus, we hypothesized that rivaroxaban could control the progression of AAA in patients with hs-CRP elevation.

METHODS

The study is a prospective, open-label, randomized, controlled clinical trial. Sixty subjects are recruited from the General Hospital of Northern Theatre Command of China. Subjects are randomly assigned (1:1) to the intervention arm (rivaroxaban) or control arm (aspirin). The primary efficacy outcome is the level of serum hs-CRP at 6 months. The secondary outcomes include imaging examination (the maximal diameter of AAA, the maximal thickness of mural thrombus, and the length of aneurysm), major adverse cardiovascular and cerebrovascular events (MACCE, including AAA transformation, non-fatal myocardial infarction, acute congestive heart failure, stent thrombosis, ischemia-driven target vessel revascularization, vascular amputation, stroke, cardiovascular death, and all-cause death), and other laboratory tests (troponin T, interleukin 6, D-dimer, and coagulation function).

DISCUSSION

The BANBOO trial tested the effect of rivaroxaban on the progression of AAA in patients with elevated Hs-CRP for the first time.

TRIAL REGISTRATION

ChiCTR2100051990, ClinicalTrials.gov, registered on 12 October 2021.

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 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.

No differences in FBN1 genotype between men with and without abdominal aortic aneurysm

BACKGROUND

Abdominal aortic aneurysm (AAA) is an aortic enlargement in which the transverse diameter reaches at least 30 mm. Certain risk factors, such as age, male gender, and smoking, are well known; however, less is known about the genetic factors involved. Fibrillin-1 (FBN1) is a protein that coordinates the deposition of elastin fibres in the extracellular matrix and is therefore likely to affect the elastic properties in the aortic wall. Previously studies have found associations between the FBN1-2/3 genotype and arterial stiffness, but how different FBN1 genotypes, AAA, and arterial stiffness are related has been less frequently investigated.

AIM

This study aimed to investigate whether there is a difference in FBN1 genotype between men with and without AAA. A further aim was to study whether the FBN1 genotype affects arterial wall stiffness differently in men with and without AAA.

METHODS

Pulse wave velocity and FBN1 genotyping were performed in 229 men (159 with AAA, 70 without AAA). Participants were recruited from ultrasound AAA surveillance programs or ongoing ultrasound screening programs from 2011 to 2016.

RESULTS

The distribution of the FBN1 genotype in the AAA and control groups were as follows: FBN1-2/2: 62% vs. 64%; FBN1-2/3: 8% vs. 14%; and FBN1-2/4: 30% vs. 21%, respectively. Men with AAA and FBN1-2/2 had increased central pulse wave velocity (p < 0.005) compared to the control group (those without AAA) with the FBN1-2/2 genotype.

CONCLUSION

No differences were found with respect to FBN1 genotypes between men with and without AAA. The development of AAA in men does not appear to be linked to a specific FBN1 genotype. Nevertheless, men with FBN1-2/2 and AAA have increased central arterial stiffness compared to men with the same FBN1 genotype but without AAA.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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.

Association Between Red Blood Cell Distribution Width-to-Albumin Ratio and Prognosis of Patients with Aortic Aneurysms

Objective

Red blood cell distribution width (RDW) is a predictor of adverse outcomes in aortic aneurysms. Recent recommendations suggest that combining RDW with other biomarkers could yield better results. We, therefore, propose evaluating the biomarker of vascular aging, albumin with RDW to predict the risk of aortic aneurysms. This study aims to explore whether the combination of RDW with albumin can effectively predict the prognosis of aortic aneurysm patients.

Methods

This retrospective cohort study was conducted among adults (age >18) with aortic aneurysms in the Medical Information Mart for Intensive Care Database III V1.4 (MIMIC-III). RAR was measured according to the red blood cell distribution width and albumin. The primary outcome was the 30-day mortality rate, and the secondary outcome was the 90-day and one-year mortality rates. Estimation of hazard ratios (HR) was obtained from Cox regression models for all-cause mortality related to red cell distribution width-to-albumin ratio (RAR) values.

Results

In total, 312 patients were involved, with an average age of 74.9 ± 10.9 years and an average RAR value of 5.4 ± 1.6 mL/g. In 30 days for all-cause mortality, the HR (95% CI) in the highest RAR group (>5.8 mL/g) in tertiles was 2.54 (1.25, 5.14) in the unadjusted model, with a significant difference compared with the reference group (P < 0.05). After adjusting for race, gender and age, there was still a correlation (P < 0.05), and the HR (95% CI) was 2.51 (1.23, 5.10). Further adjustment of possible covariates showed similar correlation in model 3 (P < 0.05), and HR (95% CI) was 2.66 (1.17, 6.01). Multivariable logistic regression shows that RAR is an independent risk factor for the outcome of aortic aneurysms after adjusting the covariates. In the subgroup analysis, we analyzed the patient’s complications, and no significant interaction was observed.

Conclusion

RAR is a risk factor for patients with aortic aneurysms. However, more in-depth research is warranted to further analyze and substantiate our findings on the role of RAR in aortic aneurysm patients.

Sex-specific normal values and determinants of infrarenal abdominal aortic diameter among non-aneurysmal elderly population

To establish age- and sex-specific distribution of the infrarenal abdominal aortic diameters (IAD) among non-aneurysmal elderly population and to investigate the associations between traditional cardiovascular risk factors and IAD in men and women. We included 4032 participants (mean age 67.2 years; 60.4% women) from the population-based Rotterdam Study, free of cardiovascular disease, who underwent IAD ultrasound assessment between 2009-2014. Linear regression analysis was used to identify determinants of IAD. The medians (inter-quartile range) of absolute IAD and body surface area (BSA)-adjusted IAD were 17.0 (15.0-18.0) mm and 9.3 (8.5-10.2) mm for women and 19.0 (18.0-21.0) mm and 9.4 (8.6-10.3) mm for men, respectively. There was a non-linear relationship between age and IAD. IAD increased steeply with advancing age and up to 70 years. After around 75 years of age, the diameter values reached a plateau. Waist circumference and diastolic blood pressure were associated with larger diameters in both sexes. Body mass index [Effect estimate (95% CI): 0.04 (0.00 to 0.08)], systolic blood pressure [- 0.01(- 0.02 to 0.00)], current smoking [0.35 (0.06 to 0.65)], total cholesterol levels [- 0.21 (- 0.31 to - 0.11)], and lipid-lowering medication [- 0.43 (- 0.67 to - 0.19)] were significantly associated with IAD in women. Sex differences in IAD values diminished after taking BSA into account. The increase in diameters was attenuated after 70 years. Differences were observed in the associations of several cardiovascular risk factors with IAD among men and women.

Metabolomic Profile of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is characterized by structural deterioration of the aortic wall, leading to aortic dilation and rupture. The aim was to compare 183 low molecular weight metabolites in AAA patients and aorta-healthy controls and to explore if low molecular weight metabolites are linked to AAA growth. Blood samples were collected from male AAA patients with fast (mean 3.3 mm/year; range 1.3-9.4 mm/year; n = 39) and slow growth (0.2 mm/year; range -2.6-1.1 mm/year; n = 40), and from controls with non-aneurysmal aortas (n = 79). Targeted analysis of 183 metabolites in plasma was performed with AbsoluteIDQ p180 kit. The samples were measured on a QTRAP 4500 coupled to an Agilent 1260 series HPLC. The levels of only four amino acids (histidine, asparagine, leucine, isoleucine) and four phosphatidylcholines (PC.ae.C34.3, PC.aa.C34.2, PC.ae.C38.0, lysoPC.a.C18.2) were found to be significantly lower (p < 0.05) after adjustment for confounders among the AAA patients compared with the controls. There were no differences in the metabolites distinguishing the AAA patients with slow or fast growth from the controls, or distinguishing the patients with slow growth from those with fast growth. The current study describes novel significant alterations in amino acids and phosphatidylcholines metabolism associated with AAA occurrence, but no associations were found with AAA growth rate.

Long Term Outcome of Screen Detected Sub-Aneurysmal Aortas in 65 Year Old Men: a Single Scan After Five Years Identifies Those at Risk of Needing AAA Repair

OBJECTIVE

The epidemiology of sub-aneurysmal aortic dilatation (SAA) 25 - 29 mm is not fully understood, and the management of SAA is debated. Lack of evidence is particularly problematic in the screening setting. This study aimed to evaluate the long term outcome of men with screen detected SAAs, focusing on progression to an abdominal aortic aneurysm (AAA), and on the AAAs reaching the threshold diameter for surgical repair.

METHODS

Between 2006 and 2015, all 65 year old men with a screen detected SAA in middle Sweden were re-examined with ultrasound after five and 10 years. The primary outcomes were expansion to AAA ≥ 30 mm and progression to AAA ≥ 55 mm. Secondary outcomes were risk factors for progression, repair rate, and mortality.

RESULTS

A total of 1 020 65 year old men with a SAA were identified, of whom 940 (92.2%; 95% confidence interval 91.0 - 93.8) had follow up. The Kaplan-Meier estimated incidence of AAA ≥ 30 mm development after the five year follow up (which was de facto carried out after a mean of 4.9 years) was 65.8% (61.6 - 69.4), all < 55 mm. The corresponding KM-estimated incidence after the 10 year follow up (carried out after a mean of 11.9 years) was 95.1% (90.1 - 97.4), and 29.7% (18.0 - 39.7) reached ≥ 55 mm. All 41 SAAs eventually expanding to ≥ 55 mm were ≥ 30 mm at the five year follow up. Of these, 32 had surgical repair with 100% survival, six have scheduled repairs, and three (7.3%) were unfit for repair. The KM estimated all cause mortality rates at five and 10 years were 7.0% and 17.9%, respectively, with no proven AAA related deaths.

CONCLUSION

A majority of SAAs eventually progress to an AAA, of which 30% are estimated to eventually reach the threshold for repair within 10 years. A follow up policy with an ultrasound examination after five years can safely and effectively identify those SAAs at risk of developing into clinically significant AAAs needing repair and may be considered for anyone with reasonably good life expectancy.

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.

Increased arterial stiffness in males with abdominal aortic aneurysm

Background

Abdominal aortic aneurysm (AAA), a localized dilatation of the abdominal aorta, has a prevalence of about 1.5%–3% among 65‐ to 70‐year‐old males in Europe. AAA confers an increased risk of developing major cardiovascular events in addition to the risk of aneurysm rupture. The aim of this study was to evaluate whether the arterial wall distensibility is altered in subjects with AAA.

Methods

Two hundred and eighty‐four male subjects (182 with AAA and 102 controls) were enrolled in the study. Arterial wall distensibility was evaluated using non‐invasive applanation tonometry to measure regional pulse wave velocity between the carotid and femoral arteries and the carotid and radial arteries. In addition, blood pressure was measured, and the pulse pressure waveform was analysed.

Results

Higher aortic augmentation index (25.1% versus 20.6%; p < .001) and higher aortic pulse wave velocity (12.3 m/s versus 10.9 m/s; p < .001) were demonstrated in the AAA cohort. The slightly higher arm pulse wave velocity in the AAA group (9.4 m/s versus 9.1 m/s; p < .05) was abolished after adjusting for mean arterial blood pressure.

Conclusions

Males with AAA have decreased aortic wall distensibility and enhanced reflection waves in central aorta during systole. These results imply that increased arterial wall stiffness may be a contributing factor to the overall higher cardiovascular risk seen in patients with AAA.

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.

Etiology and impact on outcomes of polycystic kidney disease in abdominal aortic aneurysm

PURPOSE

We investigated the etiology and impact on outcomes of polycystic kidney disease in patients with abdominal aortic aneurysm.

METHODS

Eight-hundred patients who underwent open (n = 603) or endovascular aortic repair (n = 197) were divided into three groups: no cyst (n = 204), non-polycystic kidney (n = 503), and polycystic kidney (≥ 5 cysts in the bilateral kidneys, n = 93). The characteristics and outcomes were compared among the groups.

RESULTS

In the polycystic kidney group, the age was increased and the proportions of patients with male sex, hypertension, and estimated glomerular filtration rate < 30 mL/min/1.73 m² were greater. The overall hospital mortality rates were similar. The incidence of acute kidney injury after elective open aortic repair was increased in the polycystic kidney group (12%, 17%, and 29%, P = 0.020). In the polycystic kidney group, 80 patients did not have renal enlargement or a family history of renal disease, while 13 (corresponding to 1.6% [13/800] of the overall patients), had renal enlargement, suggesting the possibility of hereditary polycystic kidney disease.

CONCLUSIONS

In our cohort, 1.6% of the patients with abdominal aortic aneurysm who underwent surgery were at risk of hereditary polycystic kidney disease. Polycystic kidney disease was associated with acute kidney injury after open aortic repair.

High-risk factors related to the occurrence and development of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a common and potentially dangerous vascular disease with many risk factors related to its occurrence and development. This review collects the results from recent studies of different comorbidities including hypertension, diabetes, and hyperlipidemia and summarizes their connections with AAA development and its underlying mechanisms. We believe that hypertension, diabetes, and hyperlipidemia can affect AAA occurrence and development, but more studies are needed to further explore the mechanisms.

Prognostic value of D-dimer and markers of coagulation for stratification of abdominal aortic aneurysm growth

Abdominal aortic aneurysm (AAA) is associated with high morbidity and mortality and is an established cause of unbalanced hemostasis. A number of hemostatic biomarkers have been associated with AAA; however, the utility of hemostatic biomarkers in AAA diagnosis and prognosis is unclear. The aim of the present study was to characterize the potential prognostic value of D-dimer and markers of altered hemostasis in a large cohort of patients with AAAs characterized by either fast or slow aneurysm growth (frequency matched for baseline diameter) and subaneurysmal dilations. We measured plasma concentrations of thrombin-antithrombin (TAT) complex, platelet factor 4 (PF4), and D-dimer in 352 patients with either fast-growing AAAs (>2 mm/y), slow-growing AAAs (<2 mm/y), subaneurysmal aortic dilations, or nonaneurysmal aortas. Plasma D-dimer and TAT were significantly elevated in both AAA and subaneurysmal dilation patients compared with controls. Individuals with D-dimer levels ≥500 ng/mL had 3.09 times the odds of subaneurysms, 6.23 times the odds of slow-growing AAAs, and 7.19 times the odds of fast-growing AAAs than individuals with D-dimer level <500 ng/mL. However, no differences in D-dimer concentration were noted between fast- and slow-growing aneurysms. Plasma D-dimer and TAT were strong independent predictors of AAA growth rate with multivariate analysis revealing a 500-ng/mL increase in D-dimer or 1-µg/mL increase in TAT led to additional 0.21-mm and 0.24-mm changes in aortic diameter per year, respectively. Rising levels of plasma TAT, in addition to D-dimer, may predict disease progression and aneurysm growth in patients with AAA or subaneurysmal dilation.

Prevalence and natural history of and risk factors for subaneurysmal aorta among 65-year-old men

Background: The aims of this study were to determine the prevalence of screening-detected subaneurysmal aorta (SAA), i.e. an aortic diameter of 2.5-2.9 cm, its associated risk factors, and natural history among 65-year-old men. Methods: A total of 14,620 men had their abdominal aortas screened with ultrasound and completed a health questionnaire containing information on smoking habits and medical history. They were categorized based on the aortic diameter: normal aorta (<2.5 cm; n = 14,129), SAA (2.5-2.9 cm; n = 258), and abdominal aortic aneurysm (AAA) (≥3.0 cm; n = 233). The SAA-group was rescanned after 5 years. Associated risk factors were analyzed. Results: The SAA-prevalence was 1.9% (95% confidence interval 1.7%-2.1%), with 57.0% (50.7%-63.3%) expanding to ≥3.0 cm within 5 years. Frequency of smoking, coronary artery disease, hypertension, hyperlipidemia, and claudication were significantly higher in those with SAA and AAA compared to those with normal aortic diameter. Current smoking was the strongest risk factor for SAA (odds ratio [OR] 2.8; P < 0.001) and even stronger for AAA (OR 3.6; P < 0.001). Men with SAA expanding to AAA within 5 years presented pronounced similarities to AAA at baseline. Conclusions: Men with SAA and AAA presented marked similarities in the risk factor profile. Smoking was the strongest risk factor with an incremental association with disease severity, and disease progression. This indicates that SAA and AAA may have the same pathophysiological origin and that SAA should be considered as an early stage of aneurysm formation. Further research on the cost-effectiveness and potential benefits of surveillance as well as smoking cessation and secondary cardiovascular prevention in this subgroup is warranted.

Anti-inflammatory diet and risk of abdominal aortic aneurysm in two Swedish cohorts

Objective

The relationship between dietary patterns and development of abdominal aortic aneurysm (AAA) is not well understood. Thus, we prospectively evaluated the association between the anti-inflammatory potential of diet and risk of AAA.

Methods

The study population included the Cohort of Swedish Men (45 072 men) and the Swedish Mammography Cohort (36 633 women), aged 45–83 years at baseline. The anti-inflammatory potential of diet was estimated using Anti-inflammatory Diet Index (AIDI) based on 11 foods with anti-inflammatory potential and 5 with proinflammatory potential (maximum 16 points) that was validated againsthigh sensitivity C reactive protein (hsCRP). Cox proportional hazard regression models were used to estimate HRs and 95% CIs. During the 14.9 years of follow-up (1 217 263 person-years), 1528 AAA cases (277 (18%) ruptured, 1251 non-ruptured) were ascertained via the Swedish Inpatient Register, the National Cause of Death Register and the Register for Vascular Surgery (Swedvasc).

Results

We observed an inverse association between the AIDI and AAA risk in women and men; HRs between extreme quartiles of the AIDI (≥8 vs ≤5 points) were 0.55 (95% CI 0.36 to 0.83) in women and 0.81 (95% CI 0.68 to 0.98) in men. The AIDI was inversely associated with both ruptured and non-ruptured AAA incidence; the HR of participants in the highest quartile of AIDI compared with those in the lowest quartile was 0.61 (95% CI 0.41 to 0.90) for ruptured AAA and 0.79 (95% CI 0.65 to 0.95) for non-ruptured AAA.

Conclusion

Adherence to diet with a high anti-inflammatory potential was associated with a reduced AAA risk, an association that was even more pronounced for AAA rupture.

Knockout of dihydrofolate reductase in mice induces hypertension and abdominal aortic aneurysm via mitochondrial dysfunction

Hypertension and abdominal aortic aneurysm (AAA) are severe cardiovascular diseases with incompletely defined molecular mechanisms. In the current study we generated dihydrofolate reductase (DHFR) knockout mice for the first time to examine its potential contribution to the development of hypertension and AAA, as well as the underlying molecular mechanisms. Whereas the homozygote knockout mice were embryonically lethal, the heterozygote knockout mice had global reduction in DHFR protein expression and activity. Angiotensin II infusion into these animals resulted in substantially exaggerated elevation in blood pressure and development of AAA, which was accompanied by excessive eNOS uncoupling activity (featured by significantly impaired tetrahydrobiopterin and nitric oxide bioavailability), vascular remodeling (MMP2 activation, medial elastin breakdown and adventitial fibrosis) and inflammation (macrophage infiltration). Importantly, scavenging of mitochondrial reactive oxygen species with Mito-Tempo in vivo completely abrogated development of hypertension and AAA in DHFR knockout mice, indicating a novel role of mitochondria in mediating hypertension and AAA downstream of DHFR deficiency-dependent eNOS uncoupling. These data for the first time demonstrate that targeting DHFR-deficiency driven mitochondrial dysfunction may represent an innovative therapeutic option for the treatment of AAA and hypertension.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Swedish men and smoking: Views on screening-detected abdominal aortic aneurysm

Abdominal aortic aneurysms (AAA), most common among elderly male smokers, often show no symptoms before rupture. To facilitate better care and counselling targeted to smoking cessation for these patients, more knowledge is required about their views. Therefore, the aim of the present study was to describe the views on AAA and smoking among male smokers with screening-detected AAA. A qualitative approach with individual interviews with 16 men with screening-detected AAA was applied. Three had quit smoking by the time of the interviews. Thematic analysis was performed, and four themes emerged: (i) accepting the course of life; (ii) the elusive AAA: a disturbing experiencing or merely a minor inconvenience?; (iii) being in safe hands; and (iv) smoking as an unexpected topic of discussion. Most of the participants felt they were in "safe hands", although thoughts about death were also evoked. However, the information about smoking cessation was unexpected, and the relationship between AAA and smoking unclear. Presenting the connection between AAA and smoking in a clear manner and motivating smoking cessation in an individually-targeted way are important.

Statin therapy improved long-term prognosis in patients with major non-cardiac vascular surgeries: a systematic review and meta-analysis

OBJECTIVE

To investigate whether statin intervention will improve the long-term prognosis of patients undergoing major non-cardiac vascular surgeries.

METHODS

Major database searches for clinical trials enrolling patients undergoing major non-cardiac vascular surgeries, including lower limb revascularization, carotid artery surgeries, arteriovenous fistula, and aortic surgeries, were performed. Subgroup analyses, stratified by surgical types or study types, were employed to obtain statistical results regarding survival, patency rates, amputation, and cardiovascular and stroke events. Odds ratio (ORs) and 95% confidence intervals (CIs) were calculated by Review Manager 5.3. Sensitivity analysis, publication bias and meta-regression were conducted by Stata 14.0.

RESULTS

In total, 34 observational studies, 8 prospective cohort studies and 4 randomized controlled clinical trials (RCTs) were enrolled in the present analysis. It was demonstrated that statin usage improved all-cause mortality in lower limb, carotid, aortic and mixed types of vascular surgery subgroups compared with those in which statins were not used. Additionally, the employment of statins efficiently enhanced the primary and secondary patency rates and significantly decreased the amputation rates in the lower limb revascularization subgroup. Furthermore, for other complications, statin intervention decreased cardiovascular events in mixed types of vascular surgeries and stroke incidence in the carotid surgery subgroup. No significant publication bias was observed. The meta-regression results showed that the morbidity of cardiovascular disease or the use of aspirin might affect the overall estimates in several subgroups.

CONCLUSIONS

This meta-analysis demonstrated that statin therapy was associated with improved survival rates and patency rates and with reduced cardiovascular or stroke morbidities in patients who underwent non-cardiac vascular surgeries.

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?

Dyslipidaemia in the elderly: to treat or not to treat?

INTRODUCTION

The elderly population (i.e. aged ≥ 65 years) is increasing worldwide. Ageing is associated with a higher incidence and prevalence of cardiovascular disease (CVD). Areas covered: The prevalence of CVD risk factors including type 2 diabetes mellitus, hypertension and dyslipidaemia also increases with advancing age, contributing to the higher absolute CVD risk observed in the elderly. The present narrative review comments on the associations of dyslipidaemia with CVD as well as the effects of lifestyle measures and lipid-lowering drugs on lipids and CVD risk with a special focus on the elderly population. Individual treatment goals and therapeutic options according to current guidelines are also reviewed. Finally, we discuss special characteristics of the elderly that may influence the efficacy and safety of drug therapy and should be considered before selection of hypolipidaemic pharmacotherapy. Expert commentary: There may be a greater CVD benefit in older patients following drug therapy compared with younger ones. Treatment goals and therapeutic options should be individualized according to current guidelines. Specific characteristics that may influence the efficacy and safety of drug therapy in the elderly should be considered in relation to dyslipidaemia treatment.

Association of high sensitivity C-reactive protein and abdominal aortic aneurysm: a meta-analysis and systematic review

OBJECTIVE

To evaluate the association of high sensitivity C-reactive protein (hsCRP) with the presence of abdominal aortic aneurysm (AAA).

METHODS

Medline, Cochrane, Embase, and Google Scholar databases were searched until 22 June 2016 using the keywords predictive factors, biomarkers, abdominal aortic aneurysm, prediction, high sensitivity C-reactive protein, and hsCRP. Prospective studies, retrospective studies, and cohort studies were included.

RESULTS

Twelve case-control studies were included in the meta-analysis with a total of 8345 patients (1977 in the AAA group and 6368 in the control group). The pooled results showed that AAA patients had higher hsCRP value than the control group (difference in means = 1.827, 95% CI = 0.010 to 3.645, p = .049). Subgroup analysis found AAA patients with medium or small aortic diameter (<50 mm) had higher hsCRP plasma levels than the control group (difference in means = 1.301, 95% CI = 0.821 to 1.781, p < .001). In patients with large aortic diameter (≥50 mm), no difference was observed in hsCRP levels between the AAA and control groups (difference in means = 1.769, 95% CI = -1.387 to 4.925, p = .272). Multi-regression analysis found the difference in means of hsCRP plasma levels between AAA and control groups decreased as aortic diameter increased (slope = -0.04, p < .001), suggesting that hsCRP levels may be inversely associated with increasing aneurysm size.

CONCLUSIONS

Our findings suggest that hsCRP levels may possibly be used as a diagnostic biomarker for AAA patients with medium or small aortic diameter but not for AAA patients with large aortic diameter. The correlation between serum hsCRP level and AAA aneurysm is not conclusive due to the small number of included articles and between-study heterogeneity.

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.

Experiences of the screening process and the diagnosis abdominal aortic aneurysm among 65-year-old men from invitation to a 1-year surveillance

The prevalence of abdominal aortic aneurysm (AAA) is reported to be 2.2%-8% among men >65 years. During recent years, screening programs have been developed to detect AAA, prevent ruptures, and thereby saving lives. Therefore, most men with the diagnosis are monitored conservatively with regular reviews. The objective of the study was to describe how men diagnosed with abdominal aortic aneurysm <55 mm discovered by screening experience the process and diagnosis from invitation to 1 year after screening. A total of eleven 65-year-old men were included in three focus groups performed in a University Hospital in Sweden. These were qualitatively analyzed using manifest and latent content analysis. The experience of the screening process and having an abdominal aortic aneurysm in a long-term perspective revealed three categories: "trusting the health care system," emphasizing the need for continual follow-ups to ensure feelings of security; "the importance size," meaning that the measure was abstract and hard to understand; and "coping with the knowledge of abdominal aortic aneurysm," denoting how everyday life was based mostly on beliefs, since a majority lacked understanding about the meaning of the condition. The men want regular surveillance and surrendered to the health care system, but simultaneously experienced a lack of support thereof. Knowing the size of the aorta was important. The men expressed insecurity about how lifestyle might influence the abdominal aortic aneurysm and what they could do to improve their health condition. This highlights the importance of communicating knowledge about the abdominal aortic aneurysm to promote men's feelings of security and giving space to discuss the size of the aneurysm and lifestyle changes.

Serum High-Sensitive C-Reactive Protein Level and CRP Genetic Polymorphisms Are Associated with Abdominal Aortic Aneurysm

BACKGROUND

Abdominal aortic aneurysm (AAA) development involves an inflammatory process with a potential genetic background. C-reactive protein (CRP) is an acute phase protein and was elevated in patients with AAA. The aim of this study was to investigate the association among serum high-sensitive CRP (hsCRP) concentration, its CRP genetic polymorphisms, and AAA.

METHODS

Serum hsCRP concentrations and abdominal aorta diameters were measured, and correlation analysis between them was performed in 155 unrelated participants with AAA and 310 non-AAA controls. Tagging single nucleotide polymorphisms (SNPs) in the CRP gene (rs1417938, rs1130864, rs1205, rs1800947) were identified via HapMap. Stratification analysis was performed to evaluate the effects of SNPs on the concentration of serum hsCRP. The association between 4 SNPs and AAA was assessed by unconditional logistic regressions.

RESULTS

Elevated serum hsCRP level was found to be an independent risk factor for AAA (odds ratio [OR] = 3.91, 95% confidence interval [CI]: 2.45, 6.23) after adjustment for confounding factors. Concentrations of serum hsCRP were significant different (P = 0.01) in 4 subgroups derived from participants with abdominal aorta diameter <20 mm, 20-29 mm, 30-54 mm, and ≥55 mm. Stratification analysis revealed there was significant high frequency of elevated hsCRP levels in subjects carrying rs1205-CC genotype compared with those carrying rs1205-TT or CT genotypes (P = 0.004, OR = 2.31, 95% CI: 1.30, 4.11), suggesting that the genotype CC of rs1205 was associated with higher serum hsCRP levels. However, the frequency of rs1205-CC in AAA patients (15.3%) was similar to control subjects (17.6%), and we could not confirm rs1205-CC was the genetic risk factor of AAA (OR = 1.18, 95% CI: 0.69, 2.01). Moreover, we found another CRP polymorphism rs1417938-TT had a significantly higher likelihood of AAA than the AT genotype (OR = 2.07, 95% CI: 1.06, 4.03) for the first time, indicating there was perhaps a role for rs14117938-T polymorphism that correlates with AAA.

CONCLUSIONS

Serum hsCRP may be related to the presence of AAA and abdominal aorta diameter. Genetic polymorphisms in CRP gene could influence the concentration of serum hsCRP and the likelihood of AAA, but the causal relationship between AAA and CRP should be demonstrated further.

Abdominal aortic aneurysm screening program using hand-held ultrasound in primary healthcare

We determined the feasibility of abdominal aortic aneurysm (AAA) screening program led by family physicians in public primary healthcare setting using hand-held ultrasound device. The potential study population was 11,214 men aged ≥ 60 years attended by three urban, public primary healthcare centers. Participants were recruited by randomly-selected telephone calls. Ultrasound examinations were performed by four trained family physicians with a hand-held ultrasound device (Vscan^®). AAA observed were verified by confirmatory imaging using standard ultrasound or computed tomography. Cardiovascular risk factors were determined. The prevalence of AAA was computed as the sum of previously-known aneurysms, aneurysms detected by the screening program and model-based estimated undiagnosed aneurysms. We screened 1,010 men, with mean age of 71.3 (SD 6.9) years; 995 (98.5%) men had normal aortas and 15 (1.5%) had AAA on Vscan^®. Eleven out of 14 AAA-cases (78.6%) had AAA on confirmatory imaging (one patient died). The total prevalence of AAA was 2.49% (95%CI 2.20 to 2.78). The median aortic diameter at diagnosis was 3.5 cm in screened patients and 4.7 cm (p<0.001) in patients in whom AAA was diagnosed incidentally. Multivariate logistic regression analysis identified coronary heart disease (OR = 4.6, 95%CI 1.3 to 15.9) as the independent factor with the highest odds ratio. A screening program led by trained family physicians using hand-held ultrasound was a feasible, safe and reliable tool for the early detection of AAA.

The Association of Serum Thrombomodulin with Endothelial Injuring Factors in Abdominal Aortic Aneurysm

Background. The aim of the present study was to evaluate the concentration of serum thrombomodulin (sTM) in the AAA patients and to examine its correlation with various factors which may potentially participate in the endothelial injury. Materials and Methods. Forty-one patients with AAA were involved and divided into subgroups based on different criteria. Concentration of sTM was measured using enzyme-linked-immunosorbent assay (ELISA). The results were compared with those obtained in 30 healthy age- and sex-matched volunteers. Results. The higher concentration of sTM was observed in AAA patients compared with those in controls volunteers [2.37 (1.97–2.82) ng/mL versus 3.93 (2.43–9.20) ng/mL, P < 0.001]. An elevated sTM associated significantly with increased triglycerides (TAG) [P = 0.022], cholesterol [P = 0.029], hsCRP [P = 0.031], and advanced glycation end products (AGEs) [P = 0.033]. Conclusions. The elevation of serum sTM level suggests that endothelial damage occurs in AAA pathogenesis. The correlations observed indicate that lipids abnormalities, inflammation, and oxidative stress may be involved in this destructive process.

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.

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 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.

Effect of lipid-modifying therapy on long-term mortality after abdominal aortic aneurysm repair: a systemic review and meta-analysis

BACKGROUND

Several observational studies have demonstrated that lipid-modifying therapy may improve long-term survival in abdominal aortic aneurysm (AAA) patients after repair. We carried out a systematic review and meta-analysis of studies evaluating the effect of lipid-modifying therapy on long-term mortality.

PATIENTS AND METHODS

We conducted a systematic search of multiple databases up to April 2014. Studies that evaluated exposure to lipid-modifying therapy, reported mortality data and hazard ratio (HR) or provided survival curve for their estimation were included in the meta-analysis. Pooled HR estimates with 95% confidence intervals (CIs) were calculated using the random-effects model.

RESULTS

Eight studies (seven cohorts, one post hoc study of a randomization controlled trial) reporting 2,605 patients on lipid-modifying therapy were included. Meta-analysis showed a significant 39% reduction in long-term mortality with lipid-modifying therapy (HR 0.61; 95% CI 0.51-0.73). After exclusion of one study which was contributing to considerable heterogeneity, a significant 33% reduction in mortality risk was a more conservative, consistent estimate (HR 0.67; 95% CI 0.59-0.77).

CONCLUSION

Meta-analysis of studies supports a protective role of lipid-modifying therapy on mortality risk after AAA repair. Aggressive lipid intervention should be recommended to those who receiving AAA repair.

Population risk factor estimates for abdominal aortic aneurysm from electronic medical records: a case control study

BACKGROUND

Using abdominal aortic aneurysm (AAA) as a model, this case-control study used electronic medical record (EMR) data to assess known risk factors and identify new associations.

METHODS

The study population consisted of cases with AAA (n =888) and controls (n =10,523) from the Geisinger Health System EMR in Central and Northeastern Pennsylvania. We extracted all clinical and diagnostic data for these patients from January 2004 to December 2009 from the EMR. From this sample set, bootstrap replication procedures were used to randomly generate 2,500 iterations of data sets, each with 500 cases and 2000 controls. Estimates of risk factor effect sizes were obtained by stepwise logistic regression followed by bootstrap aggregation. Variables were ranked using the number of inclusions in iterations and P values.

RESULTS

The benign neoplasm diagnosis was negatively associated with AAA, a novel finding. Similarly, type 2 diabetes, diastolic blood pressure, weight and myelogenous neoplasms were negatively associated with AAA. Peripheral artery disease, smoking, age, coronary stenosis, systolic blood pressure, age, height, male sex, pulmonary disease and hypertension were associated with an increased risk for AAA.

CONCLUSIONS

This study utilized EMR data, retrospectively, for risk factor assessment of a complex disease. Known risk factors for AAA were replicated in magnitude and direction. A novel negative association of benign neoplasms was identified. EMRs allow researchers to rapidly and inexpensively use clinical data to expand cohort size and derive better risk estimates for AAA as well as other complex diseases.

Hypertension overrides the protective effect of female hormones on the development of aortic aneurysm secondary to Alk5 deficiency via ERK activation

The prevalence of aortic aneurysm is five times higher in men than women among the general population. Similar sexual dimorphism also exists in syndromic aortic aneurysms triggered by TGF-β signaling disorders. To understand the responsible mechanisms, we developed an animal model where inducible deletion of the type I TGF-β receptor, Alk5, specifically in smooth muscle cells (Alk5iko) causes spontaneous aortic aneurysm formation. This model recapitulated an extreme scenario of the dimorphism in aortic aneurysm development between genders. In a comparative experiment, all Alk5iko males (n=42) developed aortic aneurysms and 26% of them died prematurely from aortic rupture. In contrast, the Alk5iko females (n=14) presented only a subclinical phenotype characteristic of scarcely scattered elastin breaks. Removal of male hormones via orchiectomy (n=7) resulted in only minimal influence on aortic pathology. However, reduction of female hormones via ovariectomy (n=15) increased the phenotypic penetrance from zero to 53%. Finally, an elevation of systolic blood pressure by 30 points unmasked the subclinical phenotype of Alk5iko females (n=17) to 59%. This exaggerated phenotypic penetrance was coupled with an early intensification of ERK signaling, a molecular signature that correlated to 100% phenotypic penetrance in normotensive Alk5iko males. In conclusion, aortic aneurysm induced by Alk5iko exhibits dimorphic incidence between genders with females less susceptible to aortic disease. This sexual dimorphism is partially the result from the protective effects of female hormones. Hypertension, a known risk factor for aortic aneurysm, is able to break the female sex protective effects through mechanisms associated with enhanced ERK activity.