Middle age cardiovascular risk factors and abdominal aortic aneurysm in older age

Female-Specific Considerations in Aortic Health and Disease

The aorta plays a central role in the modulation of blood flow to supply end organs and to optimize the workload of the left ventricle. The constant interaction of the arterial wall with protective and deleterious circulating factors, and the cumulative exposure to ventriculoarterial pulsatile load, with its associated intimal-medial changes, are important players in the complex process of vascular aging. Vascular aging is also modulated by biomolecular processes such as oxidative stress, genomic instability, and cellular senescence. Concomitantly with well-established cardiometabolic and sex-specific risk factors and environmental stressors, arterial stiffness is associated with cardiovascular disease, which remains the leading cause of morbidity and mortality in women worldwide. Sexual dimorphisms in aortic health and disease are increasingly recognized and explain-at least in part-some of the observable sex differences in cardiovascular disease, which will be explored in this review. Specifically, we will discuss how biological sex affects arterial health and vascular aging and the implications this has for development of certain cardiovascular diseases uniquely or predominantly affecting women. We will then expand on sex differences in thoracic and abdominal aortic aneurysms, with special considerations for aortopathies in pregnancy.

Vascular smooth muscle RhoA counteracts abdominal aortic aneurysm formation by modulating MAP4K4 activity

Whether a small GTPase RhoA plays a role in the pathology of abdominal aortic aneurysm (AAA) has not been determined. We show here that RhoA expression is reduced in human AAA lesions, compared with normal areas. Furthermore, incidence of AAA formation is increased in vascular smooth muscle cell (VSMC)-specific RhoA conditional knockout (cKO) mice. The contractility of the aortic rings and VSMCs from RhoA cKO mice is reduced, and expression of genes related to the VSMC contractility is attenuated by loss of RhoA. RhoA depletion activates the mitogen-activated protein (MAP) kinase signaling, including MAP4K4, in the aorta and VSMCs. Inhibition of MAP4K4 activity by DMX-5804 decreases AAA formation. Set, a binding protein to active RhoA, functions as an activator of MAP4K4 by sequestering PP2A, an inhibitor of MAP4K4, in the absence of RhoA. In conclusion, RhoA counteracts AAA formation through inhibition of MAP4K4 in cooperation with Set.

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

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

One-Year Change in Diastolic Blood Pressure and Aortic Disease-Related Mortality in a Japanese General Population Aged 50-75 Years

BACKGROUND

Aortic diseases (ADs), including aortic dissection, aortic aneurysm, and aortic rupture, are fatal diseases with extremely high mortality rates. Hypertension has been reported to be associated with AD development; however, it remains unclear whether a 1-year change in diastolic blood pressure (DBP) is a risk factor for AD-related mortality in the general population.Methods and Results:This study used a nationwide database of 235,076 individuals (aged 50-75 years) who participated in the annual "Specific Health Check and Guidance in Japan" for 2 consecutive years between 2008 and 2010. There were 55 AD-related deaths during the follow-up period of 1,770 days. All subjects were divided into 4 groups based on the baseline DBP and change in DBP at 1 year: persistent high DBP, increasing DBP, decreasing DBP, and normal DBP. Kaplan-Meier analysis demonstrated that the persistent high DBP group had the greatest risk among the 4 groups. Multivariate Cox proportional hazard regression analysis demonstrated that both DBP and 1-year change in DBP were significantly associated with AD-related deaths. The prediction capacity was significantly improved by the addition of 1-year change in DBP to confounding risk factors.

CONCLUSIONS

This study demonstrated for the first time that a 1-year change in DBP was associated with AD-related deaths in the general population. Monitoring changes in DBP are of critical importance in the primary prevention of AD-related deaths in apparently healthy subjects aged 50-75 years.

Best Practice Guidelines: Imaging Surveillance After Endovascular Aneurysm Repair

OBJECTIVE. Abdominal aortic aneurysm is a significant cause of morbidity and mortality in the United States. Endovascular aneurysm repair (EVAR) is the preferred treatment modality. Surveillance imaging after EVAR detects potential complications. The most common complication is endoleak, which can predispose the aorta to rupture. This article provides a comprehensive and evidence-based review regarding surveillance imaging after EVAR to help readers understand current societal guidelines, guide institutional protocols, and provide a framework to facilitate safe, cost-effective, and clinically relevant imaging of patients after EVAR. CONCLUSION. Lifelong surveillance is necessary for patients who have undergone EVAR. Triple-phase CT angiography (CTA) within 30 days after EVAR is necessary to triage patients appropriately and guide future imaging. Patients without endoleak on initial CTA can be monitored with annual duplex ultrasound. Patients with type I or type III endoleaks should be referred for intervention. Patients with type II and type V endoleaks should be referred for intervention only if the sac diameter grows by more than 1 cm. MR angiography should be used primarily as a problem-solving modality or in patients with contraindications to contrast media or radiation. Strong consideration should be given to more frequent surveillance in patients who have undergone EVAR who have aneurysms with a hostile neck anatomy compared with those patients with favorable neck anatomy.

Evaluation of the incidence of aortic aneurysms in patients with and without diabetes in Poland in 2012 based on the database of the National Health Fund

INTRODUCTION

There are reports that diabetes mellitus reduces the risk of aortic aneurysms and many reports that diabetes mellitus reduces the risk of abdominal aortic aneurysms. In earlier years there were also studies that did not demonstrate any effects of diabetes on the rate of aortic aneurysms.

MATERIAL AND METHODS

For the year 2012, between 1 January and 31 December, reports for services regarding treatment for aortic aneurysms were found. At the same time, the reports for services associated with diabetes with the main diagnosis of "diabetes mellitus" were found in National Health Fund databases for 2012 with the special determinants.

RESULTS

In Poland in 2012 the mean incidence of aortic aneurysms in both sexes in the group of subjects with diabetes calculated per 100,000 subjects with diabetes was 167.78 ±49.10, and the mean incidence of aortic aneurysms in both sexes in the group of subjects without diabetes calculated per 100,000 of the general population after subtracting the number of subjects with diabetes was 27.72 ±9.40. The incidence of aortic aneurysms among subjects with diabetes was significantly higher (p < 0.001) than the incidence of aortic aneurysms among subjects without diabetes.

CONCLUSIONS

Aortic aneurysms were more frequently observed in the group of patients with diabetes than in those without diabetes. Aortic aneurysms were observed three times more frequently in men than in women. In Poland in 2012, 27.20% of patients diagnosed with aortic aneurysms also had diabetes.

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.

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

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

Evaluation of the relationship between plasma lipids and abdominal aortic aneurysm: A Mendelian randomization study

Studies have reported that higher circulating levels of total cholesterol (TC), low-density lipoprotein (LDL) cholesterol and lower of high-density lipoprotein (HDL) cholesterol may be associated with increased risk of abdominal aortic aneurysm (AAA). Whether dyslipidemia causes AAA is still unclear and is potentially testable using a Mendelian randomization (MR) approach. We investigated the associations between blood lipids and AAA using two-sample MR analysis with SNP-lipids association estimates from a published genome-wide association study of blood lipids (n = 188,577) and SNP-AAA association estimates from European Americans (EAs) of the Atherosclerosis Risk in Communities (ARIC) study (n = 8,793). We used inverse variance weighted (IVW) MR as the primary method and MR-Egger regression and weighted median MR estimation as sensitivity analyses. Over a median of 22.7 years of follow-up, 338 of 8,793 ARIC participants experienced incident clinical AAA. Using the IVW method, we observed positive associations of plasma LDL cholesterol and TC with the risk of AAA (odds ratio (OR) = 1.55, P = 0.02 for LDL cholesterol and OR = 1.61, P = 0.01 for TC per 1 standard deviation of lipid increment). Using the MR-Egger regression and weighted median methods, we were able to validate the association of AAA risk with TC, although the associations were less consistent for LDL cholesterol due to wider confidence intervals. Triglycerides and HDL cholesterol were not associated with AAA in any of the MR methods. Assuming instrumental variable assumptions are satisfied, our finding suggests that higher plasma TC and LDL cholesterol are causally associated with the increased risk of AAA in EAs.

Genetic variants associated with type 2 diabetes and adiposity and risk of intracranial and abdominal aortic aneurysms

Epidemiological studies show that type 2 diabetes (T2D) is inversely associated with intracranial aneurysms (IA) and abdominal aortic aneurysms (AAA). Although adiposity has not been considered a risk factor for IA, there have been inconsistent reports relating adiposity to AAA risk. We assessed whether these observations have a genetic, causal basis. To this end, we extracted genotypes of validated single-nucleotide polymorphisms associated with T2D (n=65), body mass index (BMI) (n=97) and waist-hip ratio adjusted for BMI (WHRadjBMI) (n=47) from genotype data collected in 717 IA cases and 1988 controls, and in 818 AAA cases and 3004 controls, all of Dutch descent. For each of these three traits, we computed genetic risk scores (GRS) for each individual in these case-control data sets by summing the number of risk alleles weighted by their published effect size, and tested whether these GRS were associated with risk of aneurysm. We divided the cohorts into GRS quartiles, and compared IA and AAA risk in the highest with the lowest GRS quartile using logistic regression. We found no evidence for association in IA or AAA risk between top and bottom quartiles for the genetic risk scores for T2D, BMI and WHRadjBMI. However, additional Mendelian randomization analyses suggested a trend to potentially causal associations between BMI and WHRadjBMI and risk of AAA. Overall, our results do not support epidemiological observations relating T2D to aneurysm risk, but may indicate a potential role of adiposity in AAA that requires further investigation.

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

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

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

OBJECTIVE

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

APPROACH AND RESULTS

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

CONCLUSIONS

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

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

BACKGROUND AND AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Transthoracic Echocardiography Provides Important Long-Term Prognostic Information in Selected Patients Undergoing Endovascular Abdominal Aortic Repair

BACKGROUND

The value of performing transthoracic echocardiography (TTE) as part of the clinical assessment of patients awaiting endovascular repair of the abdominal aorta is little evaluated. We aimed to estimate the prognostic importance of information derived from TTE on long-term all-cause mortality in a selected group of patients undergoing endovascular aneurysm repair.

METHODS AND RESULTS

This was a retrospective cohort study of 273 consecutive patients selected for endovascular aneurysm repair. All patients included in the analysis underwent TTE before their procedure. Multivariable Cox regression analysis was used to estimate the effect of TTE measures on all-cause mortality. Over a mean follow-up of 3.2±1.5 years, there were 78 deaths with a mean time to death of 1.28±1.16 years. A greater tubular ascending aorta (hazard ratio [HR] 5.6, 95% confidence interval [CI] 2.77-11.33), presence of mitral regurgitation (HR 8.13, 95% CI 4.09-12.16), lower left ventricular ejection fraction (HR 0.96, 95% CI 0.93-0.98), younger age (HR 0.97, 95% CI 0.95-0.99), and presence of diabetes mellitus (HR 1.46, 95% CI 1.24-1.89) were predictors of all-cause mortality.

CONCLUSIONS

Echocardiography provides important long-term prognostic information in patients undergoing endovascular aneurysm repair. These TTE indices were more important at predicting outcome than standard conventional risk factors in this patient group. A greater tubular ascending aorta, presence of mitral regurgitation, reduced left ventricular ejection fraction, younger age, and diabetes mellitus were independently associated with long-term mortality.

No association between glucose at age 30 and aortic diameter at age 65 in men: a population-based study

OBJECTIVES

Impaired glucose metabolism and diabetes mellitus has been linked to a decreased risk for abdominal aortic aneurysm development in men. We evaluated potential relationships between blood glucose levels in 1722 men with mean age 34 years and their aortic diameter measured by ultrasound at age 65 years.

DESIGN

Prospective cohort study.

RESULTS

Mean follow-up between baseline glucose investigation and aortic ultrasound was 32.8 ± 1.8 years. There was no correlation between baseline blood glucose and later aortic diameter (r = 0.035, p = 0.146), whereas a weak correlation between body mass index (BMI) and aortic diameter was observed (r = 0.097 p < 0.001). In a partial correlation between aortic diameter and glucose levels adjusted for BMI, the correlation did not change (r = 0.011, p = 0.66). Neither were there any significant differences in mean aortic diameter between men belonging to different quartiles of baseline blood glucose levels (19.5, 19.1, 19.6 and 19.7 mm, p = 0.18).

CONCLUSION

Fasting blood glucose in 33-year-old men was not associated with their aortic diameter at age 65 years. Potential pathophysiological processes linking disturbed glucose metabolism to a decreased risk for development of abdominal aortic aneurysm in men are therefore probably not relevant until later in life.

The prevalence of abdominal aortic aneurysm is consistently high among patients with coronary artery disease

OBJECTIVE

Emerging evidence suggests high prevalence of abdominal aortic aneurysm (AAA) among patients with coronary disease. Accurate characterization of the association between coronary disease and AAA and of the actual prevalence of AAA among patients with angiography-verified coronary artery disease (CAD) is needed to evaluate the possible benefits of systematic screening for AAA.

METHODS

We searched for studies that reported the association between AAA and CAD or coronary heart disease (CHD; wider phenotype definition) in the general population (randomized controlled trials, prospective population cohorts) and those that reported the prevalence of AAA among patients with angiography-verified CAD through PubMed, Embase, and reference lists for the period between 1980 and 2014. Random-effects models were applied because of the high heterogeneity between included studies.

RESULTS

Among the general population, 23 studies reported the association between CHD and the occurrence of subclinical AAA (positive ultrasound screening; meta-analyzed odds ratio of 2.38 with 95% confidence interval [CI] of 1.78-3.19; P = 4.1 × 10(-9)). According to four prospective studies, CHD is a strong predictor of future AAA events (fatal and nonfatal; meta-analyzed hazard ratio of 3.49 with 95% CI of 2.56-4.76; P = 2.4 × 10(-15)). Altogether, 10 studies reported the prevalence of AAA among patients with angiography-verified CAD or undergoing coronary artery bypass grafting. Among men, meta-analyzed prevalence was 9.5% (95% CI, 7.6%-11.7%). Among men undergoing coronary artery bypass grafting or with three-vessel disease, the prevalence was 11.4% (95% CI, 9.1%-13.9%). Among women, the prevalence was low (0.35%).

CONCLUSIONS

The risk of subclinical AAA and future AAA events is high among patients with coronary disease. Screening for AAA among CAD patients by cardiologists would be easy and inexpensive, with possible benefits to survival and risk evaluation.

Risk profiles for aortic dissection and ruptured or surgically treated aneurysms: a prospective cohort study

BACKGROUND

Community screening to guide preventive interventions for acute aortic disease has been recommended in high-risk individuals. We sought to prospectively assess risk factors in the general population for aortic dissection (AD) and severe aneurysmal disease in the thoracic and abdominal aorta.

METHODS AND RESULTS

We studied the incidence of AD and ruptured or surgically treated aneurysms in the abdominal (AAA) or thoracic aorta (TAA) in 30 412 individuals without diagnosis of aortic disease at baseline from a contemporary, prospective cohort of middle-aged individuals, the Malmö Diet and Cancer study. During up to 20 years of follow-up (median 16 years), the incidence rate per 100 000 patient-years at risk was 15 (95% CI 11.7 to 18.9) for AD, 27 (95% CI 22.5 to 32.1) for AAA, and 9 (95% CI 6.8 to 12.6) for TAA. The acute and in-hospital mortality was 39% for AD, 34% for ruptured AAA, and 41% for ruptured TAA. Hypertension was present in 86% of individuals who subsequently developed AD, was strongly associated with incident AD (hazard ratio [HR] 2.64, 95% CI 1.33 to 5.25), and conferred a population-attributable risk of 54%. Hypertension was also a risk factor for AAA with a smaller effect. Smoking (HR 5.07, 95% CI 3.52 to 7.29) and high apolipoprotein B/A1 ratio (HR 2.48, 95% CI 1.73 to 3.54) were strongly associated with AAA and conferred a population-attributable risk of 47% and 25%, respectively. Smoking was also a risk factor for AD and TAA with smaller effects.

CONCLUSIONS

This large prospective study identified distinct risk factor profiles for different aortic diseases in the general population. Hypertension accounted for more than half of the population risk for AD, and smoking for half of the population risk of AAA.

Smoking, sex, risk factors and abdominal aortic aneurysms: a prospective study of 18 782 persons aged above 65 years in the Southern Community Cohort Study

BACKGROUND

Abdominal aortic aneurysm (AAA) is a leading cause of death in the USA. We evaluated the incidence and predictors of AAA in a prospectively followed cohort.

METHODS

We calculated age-adjusted AAA incidence rates (IR) among 18 782 participants aged ≥65 years in the Southern Community Cohort Study who received Medicare coverage from 1999-2012, and assessed predictors of AAA using multivariable Cox proportional hazards models, overall and stratified by sex, adjusting for demographic, lifestyle, socioeconomic, medical and other factors. HRs and 95% CIs were calculated for AAA in relation to factors ascertained at enrolment.

RESULTS

Over a median follow-up of 4.94 years, 281 cases were identified. Annual IR was 153/100,000, 401, 354 and 174 among blacks, whites, men and women, respectively. AAA risk was lower among women (HR 0.48, 95% CI 0.36 to 0.65) and blacks (HR 0.51, 95% CI 0.37 to 0.69). Smoking was the strongest risk factor (former: HR 1.91, 95% CI 1.27 to 2.87; current: HR 5.55, 95% CI 3.67 to 8.40), and pronounced in women (former: HR 3.4, 95% CI 1.83 to 6.31; current: HR 9.17, 95% CI 4.95 to 17). A history of hypertension (HR 1.44, 95% CI 1.04 to 2.01) and myocardial infarction or coronary artery bypass surgery (HR 1.9, 95% CI 1.37 to 2.63) was negatively associated, whereas a body mass index ≥25 kg/m(2) (HR 0.72; 95% CI 0.53 to 0.98) was protective. College education (HR 0.6, 95% CI 0.37 to 0.97) and black race (HR 0.44, 95% CI 0.28 to 0.67) were protective among men.

CONCLUSIONS

Smoking is a major risk factor for incident AAA, with a strong and similar association between men and women. Further studies are needed to evaluate benefits of ultrasound screening for AAA among women smokers.

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.

Sex differences in the association between smoking and abdominal aortic aneurysm

Background

It is unclear whether recommendations about ultrasound screening programmes for abdominal aortic aneurysm (AAA) among men should be extended to include women who smoke. The aim was to examine sex-specific dose–response associations between AAA risk and smoking status, pack-years smoked and time since smoking cessation.

Methods

Women in the Swedish Mammography Cohort and men in the Cohort of Swedish Men were followed up from 1998 to 2011. AAA was identified through linkage of the cohorts to the Swedish Inpatient Register and the Swedish National Register for Vascular Surgery (Swedvasc), and not through general ultrasound screening. Associations were estimated with Cox proportional hazards models.

Results

The cohorts included 35 550 women and 42 596 men, aged 46–84 years. During follow-up, AAA was identified in 199 women and 958 men. The incidence of AAA per 100 000 person-years was 76 among men who never smoked and 136 among women who currently smoke. Regarding AAA risk, women were more sensitive to current smoking (Pinteraction= 0·002). Compared with never smokers, the hazard ratio (HR) for AAA in current smokers with more than 20 pack-years was 10·97 (95 per cent confidence interval 7·41 to 16·26) among women and 6·55 (5·36 to 7·99) among men. Following smoking cessation, women had a more rapid decline in excess risk (Pinteraction &lt; 0·001). The risk was halved after 11 years (HR 0·51, 0·32 to 0·81) among women and after 23 years (HR 0·50, 0·42 to 0·60) among men.

Conclusion

There were sex differences in the associations between smoking status and AAA risk. These data support further investigation of targeted AAA screening among women who smoke.

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.

Current status of medical treatment for abdominal aortic aneurysm

Although cardiovascular disease is widely recognized as the leading cause of death, a lesser known fact is that aortic aneurysm is the 15th leading cause of death over the age of 65 years in the USA. The golden standard of the treatments are invasive interventions either with open surgical repair (OS) or endovascular aneurysm repair (EVAR). The concept of medical treatment is to prevent abdominal aortic aneurysm (AAA) from rupture and avoid surgical treatment by preventing aneurysm enlargement or even reducing aneurysm size. Matrix metalloproteinases (MMP) are structurally related metalloendopeptidases that can degrade the extracellular matrix and is thought to play important roles in AAA. There are many proposed pharmacological treatments including: β-blockers, angiotensin-converting enzyme inhibitor (ACE inhibitors), angiotensin-receptor blocker (ARB), statins, macrolides and, doxycycline, an inhibitor of the MMP. The latter is a potential promising drug as medical treatment for AAA and the Non-invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA(3)CT) is currently ongoing in the USA. Here, the pathophysiology and potential medical therapy for AAA will be reviewed.

The relative risk of aortic aneurysm in patients with giant cell arteritis compared with the general population of the UK

OBJECTIVES

To evaluate the risk of aortic aneurysm in patients with giant cell arteritis (GCA) compared with age-, gender- and location-matched controls.

METHODS

A UK General Practice Research Database (GPRD) parallel cohort study of 6999 patients with GCA and 41 994 controls, matched on location, age and gender, was carried out. A competing risk model using aortic aneurysm as the primary outcome and non-aortic-aneurysm-related death as the competing risk was used to determine the relative risk (subhazard ratio) between non-GCA and GCA subjects, after adjustment for cardiovascular risk factors.

RESULTS

Comparing the GCA cohort with the non-GCA cohort, the adjusted subhazard ratio (95% CI) for aortic aneurysm was 1.92 (1.52 to 2.41). Significant predictors of aortic aneurysm were being an ex-smoker (2.64 (2.03 to 3.43)) or a current smoker (3.37 (2.61 to 4.37)), previously taking antihypertensive drugs (1.57 (1.23 to 2.01)) and a history of diabetes (0.32 (0.19 to 0.56)) or cardiovascular disease (1.98 (1.50 to 2.63)). In a multivariate model of the GCA cohort, male gender (2.10 (1.38 to 3.19)), ex-smoker (2.20 (1.22 to 3.98)), current smoker (3.79 (2.20 to 6.53)), previous antihypertensive drugs (1.62 (1.00 to 2.61)) and diabetes (0.19 (0.05 to 0.77)) were significant predictors of aortic aneurysm.

CONCLUSIONS

Patients with GCA have a twofold increased risk of aortic aneurysm, and this should be considered within the range of other risk factors including male gender, age and smoking. A separate screening programme is not indicated. The protective effect of diabetes in the development of aortic aneurysms in patients with GCA is also demonstrated.

The strange relationship between diabetes and abdominal aortic aneurysm

In a 1997 report of a large abdominal aortic aneurysm (AAA) screening study, we observed a negative association between diabetes and AAA. Although this was not previously described and negative associations between diseases are rare, the credibility of the finding was supported by consistent results in several previous studies and by the absence of an obvious artifactual explanation. Since that time, a variety of studies of AAA diagnosis, both by screening and prospective clinical follow-up, have confirmed the finding. Other studies have reported slower aneurysm enlargement and fewer repairs for rupture in diabetics. The seeming protective effect of diabetes for AAA contrasts with its causal role in occlusive vascular disease and so provides a strong challenge to the traditional view of AAA as a manifestation of atherosclerosis. Research focused on a protective effect of diabetes has already increased our understanding of the etiology of AAA, and might eventually pave the way for new therapies to slow AAA progression.

Complex pathologies of angiotensin II-induced abdominal aortic aneurysms

Angiotensin II (AngII) is the primary bioactive peptide of the renin angiotensin system that plays a critical role in many cardiovascular diseases. Subcutaneous infusion of AngII into mice induces the development of abdominal aortic aneurysms (AAAs). Like human AAAs, AngII-induced AAA tissues exhibit progressive changes and considerable heterogeneity. This complex pathology provides an impediment to the quantification of aneurysmal tissue composition by biochemical and immunostaining techniques. Therefore, while the mouse model of AngII-induced AAAs provides a salutary approach to studying the mechanisms of the evolution of AAAs in humans, meaningful interpretation of mechanisms requires consideration of the heterogeneous nature of the diseased tissue.

Reproductive history in women with abdominal aortic aneurysms

BACKGROUND

The prevalence of abdominal aortic aneurysms (AAAs) differs considerably between the sexes, illustrated by the male/female ratio 4-6:1. Women are also reported to have a higher risk of rupture, and a poorer outcome compared with men. The primary aim of this study was to investigate if women with AAA have a different reproductive history compared with other women. The secondary aim was to study if women with a larger AAA differ in their reproductive history from women with a smaller AAA.

METHOD

This case-control study was performed in October 2009 and included 140 consecutively monitored women with AAA and 140 with peripheral arterial disease (PAD) at the Department of Vascular Surgery at Karolinska University Hospital, Stockholm. AAA was defined as AAA diameter >3 cm, and women with AAA were subdivided into groups with AAA diameter ≥5 cm and diameter <5 cm. A validated questionnaire was used to obtain information about participants' reproductive history and general health. The response rate was 70% (n = 196).

RESULTS

Women with AAA were smokers to a greater extent than women with PAD (previous, 52% vs 46%; current, 46% vs 34%, P = .001). Diabetes mellitus was more prevalent in women with PAD (28%) than in women with AAA (15%, P = .034). Angina pectoris occurred more often in women with AAA (26%) than in women with PAD (11%, P = .026). No significant difference was found between PAD and AAA women regarding statin use, treatment for hypertension, prior myocardial infarction, and body mass index (BMI). The 54 women with AAA ≥5 cm and the 44 women with AAA <5 cm were similar in age (76 vs 76 years, P = .908) and BMI (25.7 vs 24.0 kg/m(2), P = .66). No difference was noted in the occurrence of other risk factors between women with AAA ≥5 cm and women with AAA <5 cm. Mean age at menopause was lower in women with AAA ≥5 cm than in women with AAA <5 cm and in women with PAD (47.7 vs 49.9 vs 49.7 years, P = .011). Apart from menopausal age, the groups had a similar reproductive history, including hormone replacement therapy, parity, use of contraceptives, prior gynecological surgery, and breast cancer.

CONCLUSION

These findings suggest that women with larger AAA reach menopausal age earlier, and this could influence an earlier onset of aneurysmatic disease or an increase in aneurysm growth. The true role of endogenous estrogen in aneurysm development and expansion is yet to be investigated.

Endothelial dysfunction of resistance vessels in female apolipoprotein E-deficient mice

BACKGROUND

The effects of hypercholesterolemia on vasomotricity in apolipoprotein E-deficient (ApoE) mice, a murine model of spontaneous atherosclerosis, are still unclear. The studies were mostly performed in conductance vessels from male mice fed a high-fat diet. In the present study, we evaluated the endothelial function of resistance vessels from normal C57BL/6 (C57) and hypercholesterolemic (ApoE) female mice in both normal and ovariectomized conditions.

METHODS

Twenty week-old C57 and ApoE mice underwent ovariectomy or sham surgery and were studied 30 days later. The vascular reactivities to norepinephrine (NE, 10(-9) to 2 x 10(-3) mol/L), acetylcholine (ACh) and sodium nitroprusside (SNP) (10(-10) to 10(-3) mol/L) were evaluated in the isolated mesenteric arteriolar bed through dose-response curves.

RESULTS

ACh-induced relaxation was significantly reduced (P < 0.05) in ApoE compared with C57 animals, as indicated by both the maximal response (37 +/- 4% vs. 72 +/- 1%) and the LogEC50 (-5.67 +/- 0.18 vs. -6.23 +/- 0.09 mol/L). Ovariectomy caused a significant impairment in ACh-induced relaxation in the C57 group (maximal response: 61 +/- 4%) but did not worsen the deficient state of relaxation in ApoE animals (maximal response: 39 +/- 5%). SNP-induced vasorelaxation and NE-induced vasoconstriction were similar in ApoE and C57 female mice.

CONCLUSION

These data show an impairment of endothelial function in the resistance vessels of spontaneously atherosclerotic (ApoE-deficient) female mice compared with normal (C57) female mice. The endothelial dysfunction in hypercholesterolemic animals was so marked that ovariectomy, which impaired endothelial function in C57 mice, did not cause additional vascular damage in ApoE-deficient mice.

Association between serum lipoproteins and abdominal aortic aneurysm

The importance of dyslipidemia in the etiology of abdominal aortic aneurysm (AAA) is poorly defined, in part because previous association analyses have often not considered the use of current lipid-modifying medications. Medications targeted at altering the concentrations of circulating lipids have an established role in occlusive atherosclerosis but are of unknown value in the primary prevention of AAA. We examined the association between fasting serum levels of triglycerides low- and high-density lipoprotein and the presence of an AAA in a cohort of 3,327 men aged 65 to 83 years. The analyses were adjusted for established risk factors of AAA and the prescription of lipid-modifying agents using multiple logistic regression analysis. Of the 3,327 men, 1,043 (31%) were receiving lipid-modifying therapy at the fasting lipid measurement. The lipid-modifying therapy was statins in most cases (n = 1,023). The serum high-density lipoprotein concentrations were lower in patients with AAAs. The serum high-density lipoprotein concentration was independently associated with a reduced risk of having an AAA in men not receiving current lipid-modifying therapy (odds ratio 0.72, 95% confidence interval 0.56 to 0.93 per 0.4-mM increase) and in the total cohort (odds ratio 0.76, 95% confidence interval 0.63 to 0.91 per 0.4-mM increase, adjusted for lipid-modifying therapy). The concentrations of low-density lipoprotein and triglycerides were not associated with the presence of AAAs. In conclusion, high-density lipoprotein appeared to be the most important lipid in predicting the risk of AAA development, with potential value as a therapeutic target. Current cardiovascular strategies aimed at lowering low-density lipoprotein might not have any effect on the prevention of AAAs.

Endovascular repair of abdominal aortic aneurysms: only a mechanical solution for a biological problem?

Endovascular aneurysm repair has matured significantly over the last 20 years and is becoming increasingly popular as a minimally invasive treatment option for patients with abdominal aortic aneurysms (AAA). Long-term durability of this fascinating treatment, however, is in doubt as continuing aneurysmal degeneration of the aortoiliac graft attachment zones is clearly associated with late adverse sequelae. In recent years, our growing understanding of the physiopathology of AAA formation has facilitated scrutiny of various potential drug treatment concepts. In this article we review the mechanical and biological challenges associated with endovascular treatment of infrarenal AAAs and discuss potential approaches to ongoing aneurysmal degeneration, which hampers long-term outcomes of this minimally invasive therapy.

Decrease in total aneurysm-related deaths in the era of endovascular aneurysm repair

OBJECTIVE

With the expansion of elective abdominal aortic aneurysm (AAA) repair after the introduction of endovascular aneurysm repair (EVAR), there is a concern that even with a lower operative mortality there could be an increasing number of aneurysm-related deaths. To evaluate this, we looked at national trends in AAA repair volume as well as mortality rates after intact and ruptured AAA repair encompassing the introduction of EVAR.

METHODS

Patients with intact or ruptured AAA undergoing open repair or EVAR and all those with a diagnosis of ruptured AAA were identified within the 1993 to 2005 Nationwide Inpatient Sample database using International Classification of Diseases, 9th Revision, diagnosis and procedure codes. The number of repairs, number of rupture diagnoses without repair, number of deaths, and associated mortality rates were measured for each year of the database. Outcomes (mean annual volumes) were compared from the pre-EVAR era (1993 to 1998) with the post-EVAR era (2001 to 2005).

RESULTS

Since its introduction, EVAR increased steadily and accounted for 56% of repairs yet only 27% of the deaths for intact repairs in 2005. The mean annual number of intact repairs increased from 36,122 in the pre-EVAR era to 38,901 in the post-EVAR era, whereas the mean annual number of deaths related to intact AAA repair decreased from 1693 pre-EVAR to 1207 post-EVAR (P < .0001). Mortality for all intact AAA repair decreased from 4.0% to 3.1% (P < .0001) pre-EVAR and post-EVAR, but open repair mortality was unchanged (open repair, 4.7% to 4.5%, P = .31; EVAR, 1.3%). During the same time, the mean annual number of ruptured repairs decreased from 2804 to 1846, and deaths from ruptured AAA repairs decreased from 2804 to 1846 (P < .0001). Mortality for ruptured AAA repair decreased from 44.3% to 39.9% (P < .0001) pre-EVAR and post-EVAR (open repair, 44.3% to 39.9%, P < .001; EVAR, 32.4%). The overall mean annual number of ruptured AAA diagnoses (9979 to 7773, P < .0001) and overall mean annual deaths from a ruptured AAA decreased post-EVAR (5338 to 3901, P < .0001).

CONCLUSION

Since the introduction of EVAR, the annual number of deaths from intact and ruptured AAA has significantly decreased. This coincided with an increase in intact AAA repair after the introduction of EVAR and a decrease in ruptured AAA diagnosis and repair volume.

Prevalence of risk factors, coronary and systemic atherosclerosis in abdominal aortic aneurysm: comparison with high cardiovascular risk population

Background:

Abdominal aortic aneurysm (AAA) is considered a manifestation of atherosclerosis, however there are epidemiologic, biochemical, and structural differences between occlusive atherosclerosis and AAA. The pathogenesis of AAA involves several factors, first of all destruction of collagen and elastin in the aortic wall. Classical risk factors may influence the evolution and development of AAA, though no consistent association has been found. Aims of the study were to evaluate associations between risk factors and to establish the prevalence of carotid, peripheral vascular and coronary atherosclerosis in patients with AAA.

Methods:

We studied 98 patients with AAA (Group 1) awaiting surgery compared with high cardiovascular risk population having two or more risk factors (n = 82 Group 2). We evaluated traditional risk factors and we studied by eco-doppler and echocardiography the presence of carotid peripheral and coronaric atherosclerosis in two groups.

Results:

We found a higher incidence of AAA in males (p < 0.01). The prevalence of infrarenal AAA was significantly higher than suprarenal AAA (81 vs 17 p < 0.001). No differences in total cholesterol (199 ± 20 vs. 197 ± 25 mg/dl), low-density lipoprotein (142 ± 16 vs. 140 ± 18 mg/dl), triglycerides (138 ± 45 vs. 144 ± 56 mg/dl), glycemia (119 ± 15 vs. 122 ± 20 mg/dl), and fibrinogen (388 ± 154 vs. 362 ± 92 mg/dl) were found between groups. We demonstrated significant differences for cigarette smoking (p < 0.002), systolic and diastolic blood pressure (150 ± 15 vs. 143 ± 14 mmHg and 88 ± 6 vs. 85 ± 7 mmHg, p < 0.0001 and p < 0.05, respectively) and high sensititivity C reactive protein (2.8 ± 1.3 vs. 1.3 ± 0.7 mg/dl, p < 0.001). High-density lipoprotein (HDL) cholesterol levels were significant greater in Group 1 than Group 2 (p < 0.003). Subgroups of patients with AAA and luminal thrombus showed higher fibrinogen levels (564 ± 235 vs. 341 ± 83 mg/dl, p < 0.001) and lower HDL than in controls (46.6 ± 6.5 vs. 52.1 ± 7.8 mg/dl, p < 0.01). We did not find any difference in body mass index, or prevalence of coronary and peripheral atherosclerosis between groups. Conversely, we found higher prevalence of carotid atherosclerosis in Group 2 (9% vs. 25%, p < 0.004).

Conclusion:

Our AAA patients had fewer and different risk factors respect to patients with atherosclerosis. Only elevated blood pressure, C reactive protein, and smoking showed a significant association with AAA. Atherosclerosis in other arterial districts did not differ respect to subjects with high cardiovascular risk. Our results confirm the hypothesis that AAA and atherosclerosis are two different pathological entities with different risk profiles.

Advantages and pitfalls of abdominal aortic aneurysm screening in high-risk patients

Screening for abdominal aortic aneurysm (AAA) has been suggested for older men. Our aim was to determine the effect of participant selection on prevalence and treatment suitability. Men aged 65 to 75 years attending cardiology clinics composed the high-risk group; the control group was from the community. AAA screening was performed, with follow-up or surgery arranged. Four hundred eight of 651 (62.7%) high-risk men and 109 of 908 (45.0%; p< .0001) men attended from the community. In the high-risk patients, 40 AAAs were diagnosed, with a mean diameter of 41.4 mm (+/-10.4 mm). In the control group, 22 new AAAs were found, with an average size of 40.9 mm (+/-10.4 mm). Higher polypharmacy existed in the high-risk group (4.6+/-2.2 vs 2.3+/-2.0; p< .0001). More aneurysm patients were on dual-antiplatelet therapy (32.5% vs 15.4%; p= .048) compared with the overall high-risk group. In this group, three underwent surgery; one was anatomically unsuitable for endovascular repair and medically unfit for open repair. Two in the control group had surgery. A higher prevalence of AAA is encountered in high-risk men. Most aneurysms are small; however, a significant proportion of the aneurysms detected were of a size that would warrant repair. The decision to perform surgical repair is likely to be influenced by the comorbid medical conditions, which placed the patients in the high-risk category.

Abdominal aortic aneurysm events in the women's health initiative: cohort study

OBJECTIVE

To assess the association between potential risk factors and subsequent clinically important abdominal aortic aneurysm events (repairs and ruptures) in women.

DESIGN

Large prospective observational cohort study with mean follow-up of 7.8 years.

SETTING

40 clinical centres across the United States.

PARTICIPANTS

161 808 postmenopausal women aged 50-79 enrolled in the women's health initiative.

MAIN OUTCOME MEASURES

Association of self reported or measured baseline variables with confirmed abdominal aortic aneurysm events assessed with multiple logistic regression.

RESULTS

Events occurred in 184 women and were strongly associated with age and smoking. Ever smoking, current smoking, and amount smoked all contributed independent risk. Diabetes showed a negative association (odds ratio 0.29, 95% confidence interval 0.13, 0.68), as did postmenopausal hormone therapy. Positive associations were also seen for height, hypertension, cholesterol lowering treatment, and coronary and peripheral artery disease.

CONCLUSIONS

Our findings confirm the strong positive associations of clinically important abdominal aortic aneurysm with age and smoking in women and the negative association with diabetes previously reported in men.

Are periods of low atmospheric pressure associated with an increased risk of abdominal aortic aneurysm rupture?

INTRODUCTION

Seasonal variation in rates of abdominal aortic aneurysm (AAA) rupture has previously been described. However, only two studies, to date, have suggested that periods of low atmospheric pressure may account for this observation and both returned apparently contradictory findings. The objective of this study was to demonstrate whether periods of low atmospheric pressure are indeed associated with an increased likelihood of AAA rupture presentation.

PATIENTS AND METHODS

A total of 182 cases of ruptured AAA were identified retrospectively from two centres over a 6-year period from January 2000 to December 2005. Local meteorological data for the corresponding period was obtained from the UK Meteorological Office which was recorded daily at a local weather station. Statistical analysis using Student's t-test, ANOVA (Kruskal-Wallis), linear regression and multiple logistic regression was conducted to identify significant relationships from the data.

RESULTS

Days of rupture presentation were associated with a significantly lower daily mean atmospheric pressure when compared with days when no rupture occurred (P = 0.025). Multiple logistic regression demonstrated a significant association between low daily atmospheric pressure and rupture incidence (P = 0.033) which appeared to be independent of temperature. A significant seasonal trough in atmospheric pressure was observed in October and November (Kruskal-Wallis, P < 0.001); however, there was no corresponding autumnal peak in rupture incidence (P = 0.232).

CONCLUSIONS

The findings of this study appear to confirm the assertion that low atmospheric pressure is associated with an increased risk of AAA rupture on a day-to-day basis; however, no evidence was identified to support a change in policy regarding prioritising elective surgery based on seasonal risk.

Should Abdominal Aortic Aneurysm Be Managed Differently in Women?

Although abdominal aortic aneurysm (AAA) is 4 to 6 times more common in men than in women, more than a third of all AAA deaths occur in women. In several reports from the UK Small Aneurysm Trial group, the rupture rate for women was 3–4 times that seen in men. A joint council of several vascular societies responded to these observations with the recommendation that AAA should be repaired earlier in women, at 4.5 cm to 5.0 cm rather than the 5.5 cm established in randomized trials for men. However, this recommendation does not appear to reflect a full consideration of the evidence. For example, population-based studies have reported mortality following AAA repair to be 40–60% higher in women than in men. Also, in the UK Small Aneurysm Trial itself, there was no trend toward a benefit from early repair in women. The totality of evidence available at present provides no good reason to alter for women the 5.5 cm threshold for elective repair established for men by the small AAA trials.

The development of abdominal aortic aneurysms in mice is enhanced by benzo(a)pyrene

Cigarette smoking has been strongly associated with abdominal aortic aneurysm (AAA), but the components of tobacco smoke involved in AAA have not been identified. Benzo(a)pyrene (BaP) is an important constituent in cigarette smoke capable of induction of alterations strikingly similar to the pathological changes seen during AAA development. We therefore hypothesized that BaP exposure contributes to the development of AAA. In this study, C57/B6J mice were treated with vehicle, angiotensin II (AngII) (0.72 mg/kg/day), BaP (10 mg/kg/week), or the combination of AngII and BaP, for 5 weeks, and then examined for incidence of AAA and pathological changes of the aortic wall. Results showed that incidence of AAA formation in C57/B6J mice treated with BaP and AngII was significantly higher than that in AngII-treated mice (7 of 12 compared to 2 of 12). Further, five mice in the group treated with AngII/BaP and one in the group treated with AngII exhibited AAA rupture and hematoma. BaP caused macrophage infiltration, disarray of elastic lamella, and loss of vascular smooth muscle cells (VSMCs). We conclude that BaP aggravates AAA formation and rupture in C57/B6J mice by promoting macrophage infiltration, degeneration of elastic lamella, and loss of VSMCs in the aortic wall.

Novel insight into the pathobiology of abdominal aortic aneurysm and potential future treatment concepts

The patient with abdominal aortic aneurysm (AAA) commonly is a nondiabetic, white man with a history of smoking. Moreover, AAA represents a leading cause of death in elderly men in Western countries. The purpose of this manuscript is to review current evidence as to the pathobiology of AAA as well as potential future drug targets to prevent progression of AAA.

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

BACKGROUND

Identification of risk factors for and early diagnosis of clinically significant abdominal aortic aneurysm (AAA) before rupture is vital to optimize outcomes in these patients. Our aim was to examine traditional and three novel potential risk factors (abdominal obesity, white blood cell count, and kidney function) for abdominal aortic aneurysm (AAA, comprising discharge diagnosis or surgical repair) in a large multiethnic population.

METHODS

Cohort study (N =104,813) conducted at an integrated health care delivery system in northern California.

RESULTS

After a median of 13 years, 605 AAA events (490 in men and 115 in women; 91 [15%] fatal) were observed. In multivariable analysis, factors significantly associated with risk of clinically detected AAA included male gender, older age, black race (inversely), low educational attainment, cigarette smoking (with dose-response relation), height, treated and untreated hypertension, high total serum cholesterol, elevated white blood cell count, known coronary artery disease, history of intermittent claudication, and reduced kidney function. A significant Asian race by gender interaction was found such that Asian race had a (borderline significant) protective association with AAA in men but not in women.

CONCLUSIONS

Our findings confirm that major atherosclerotic risk factors, except for diabetes and obesity, are also prospectively related to AAA and suggest that elevated white blood cell count and reduced kidney function may improve risk stratification for clinically relevant AAA.

Reduced aortic wall stress in diabetes mellitus

OBJECTIVE

Most risk factors are similar for abdominal aortic aneurysm (AAA) and atherosclerosis, e.g. smoking, male gender, age, high blood pressure, hyperlipidemia. Diabetes mellitus however, is a risk factor for atherosclerosis, but diabetic patients seldom develop AAA. The reason for this discrepancy is unknown. Increased aortic wall stress seems to be an etiologic factor in the formation, growth and rupture of AAA in man. The aim of our study was to study the wall stress in the abdominal aorta in diabetic patients compared with healthy controls.

METHODS

39 patients with diabetes mellitus and 46 age - and sex matched healthy subjects were examined with B-mode ultrasound to determine the lumen diameter (LD) and intima-media thickness (IMT) in the abdominal aorta (AA) and the common carotid artery (CCA). Diastolic blood pressure (DBP) was measured non-invasively in the brachial artery. LaPlace law was used to calculate circumferential wall stress.

RESULTS

Age, DBP, and LD in the abdominal aorta were not significantly different in the diabetic patients compared to controls. IMT in the AA was larger in the diabetic patients, 0.89+/-0.17 vs 0.73+/-0.11 mm (p<.001). Accordingly aortic wall stress was reduced in the diabetics, 7.8+/-1.7 x 10(5) vs 9.7+/-1.9 x 10(5)dynes/cm(2) (p<.001).

CONCLUSIONS

Wall stress in the abdominal aorta is reduced in diabetes mellitus. This is mainly due to a thicker aortic wall compared to healthy controls. The reduced aortic wall stress coincides with the fact that epidemiological studies have shown a decreased risk of aneurysm development in diabetic patients.

Concomitant Detection of Systemic Atherosclerotic Disease while Screening for Abdominal Aortic Aneurysm

INTRODUCTION

Although population screening for abdominal aortic aneurysm (AAA) has/had a significant impact on disease-specific mortality, coexisting systemic atherosclerosis represents the major impediment to improved longevity. We examined the feasibility and yield of full cardiovascular assessment concomitant with screening for AAA detection.

METHODS

A total of 1032 asymptomatic men over the age of 50 years (328 were >60 years) underwent a detailed cardiac health questionnaire, sphygmomanometry, body mass index calculation, fasting lipid profiling, ultrasonographic (US) examination of their infrarenal aorta and carotid arteries, and treadmill exercise stress testing. Framingham and SCORE project estimations of the 10-year risk of ischemic heart disease (IHD) and fatal cardiovascular disease (CVD) of any cause were calculated for the men with an AAA and in those>60 years but with neither AAA nor known cardiac disease.

RESULTS

Overall, we detected an AAA>3 cm in 30 men (2.9%). Unaddressed obesity, smoking, hypertension, impaired glucose metabolism, and hypercholesterolemia were commonly identified in individuals both with and without an AAA, being notably frequent in those>60 years without an AAA. The 10-year risk of IHD and CHD in those>60 years was similar regardless of whether an AAA was present. Doppler screening for significant carotid stenosis had detection rates similar to those for aortic US scanning, being most useful in those>65 years of age. Exercise stress testing, however, was of only limited value when used nonselectively.

CONCLUSIONS

Modifiable atherosclerotic disease and cardiovascular risk can be readily detected in individuals presenting for AAA screening and are present to a significant degree at an earlier age. Consideration of selected, additional investigations is required to maximize the value of generalized screening programs.