Influence of diagnostic criteria on the prevalence of abdominal aortic aneurysm

Comparisons of risk factors and outcomes between abdominal aortic aneurysm and peripheral arterial disease: a case-control study

Background

There is a paucity of data on direct comparison of clinical measures in patients with abdominal aortic aneurysm (AAA) and those with peripheral arterial disease (PAD). Here, we examine the risk factors and outcomes between these 2 conditions.

Methods

Group differences were examined by Fisher's exact tests with Bonferroni correction, postoperative complications (including delirium and pneumonia) and LOS by logistic regression, and mortality by Cox regression, adjusted for age, sex, smoking, co-morbidities and medications.

Results

In total, 160 men and 33 women aged 74.5years (SD = 9.4) were referred for preoperative cardiac assessment for AAA (n = 70) and PAD (n = 123). Vascular surgery was performed in 148 patients (70% of AAA; 80.5% of PAD). Myocardial infarct was more prevalent in AAA, and diabetes more in PAD, whilst atrial fibrillation, stroke, congestive heart failure and hypertension did not differ between groups. Compared to patients with PAD, there were higher proportions of patients with AAA prescribed with cardiovascular medications, and developed post-operative complications in hospital: odds ratio = 7.34 (95% CI, 2.26-23.84, P < .001), and stayed in hospital >1week: odds ratio = 2.60 (95% CI, 1.15-5.85, P = .021). Compared to those with AAA, patients with PAD were at greater risk of death in the entire sample: hazard ratio = 3.34 (95% CI, 1.64-6.79), and in those who underwent vascular surgery: hazard ratio = 4.90 (95% CI, 1.88-12.79). Left ventricular function did not relate to outcomes.

Conclusions

Differences between AAA and PAD in risk profile and management which may have a bearing on higher risk of death associated with PAD. More intensive cardiovascular management may help improve their outcomes.

How to improve epidemiological trustworthiness concerning abdominal aortic aneurysms

BackgroundResearch on degenerative abdominal aortic aneurysms (AAA) is hampered by complex pathophysiology, sub-optimal pre-clinical models, and lack of effective medical therapies. In addition, trustworthiness of existing epidemiological data is impaired by elements of ambiguity, inaccuracy, and inconsistency. Our aim is to foster debate concerning the trustworthiness of AAA epidemiological data and to discuss potential solutions.MethodsWe searched the literature from the last five decades for relevant epidemiological data concerning AAA development, rupture, and repair. We then discussed the main issues burdening existing AAA epidemiological figures and proposed suggestions potentially beneficial to AAA diagnosis, prognostication, and management.ResultsRecent data suggest a heterogeneous scenario concerning AAA epidemiology with rates markedly varying by country and study cohorts. Overall, AAA prevalence seems to be decreasing worldwide while mortality is apparently increasing regardless of recent improvements in aortic-repair techniques. Prevalence and mortality are decreasing in high-income countries, whereas low-income countries show an increase in both. However, several pieces of information are missing or outdated, thus systematic renewal is necessary. Current AAA definition and surgical criteria do not consider inter-individual variability of baseline aortic size, further decreasing their reliability.ConclusionsSwitching from flat aortic-size thresholds to relative aortic indices would improve epidemiological trustworthiness regarding AAAs. Aortometry standardization focusing on simplicity, univocity, and accuracy is crucial. A patient-tailored approach integrating clinical data, multi-adjusted indices, and imaging parameters is desirable. Several novel imaging modalities boast promising profiles for investigating the aortic wall. New contrast agents, computational analyses, and artificial intelligence-powered software could provide further improvements.

Difference in risk factor profile for abdominal aortic aneurysm and thoracic aortic aneurysm

OBJECTIVE

Previous studies suggest partly different risk factor profiles of thoracic aortic aneurysms (TAAs) and abdominal aortic aneurysms (AAAs), but prospective data are scarce. The purpose of this prospective population-based case-control study was to investigate differences in risk factor profile between TAAs and AAAs.

METHODS

Participants in two prospective population-based studies, the Västerbotten Intervention Project (VIP) and the Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) study, between 1986 and 2010, underwent cardiovascular risk assessments, including blood samples, oral glucose tolerance test, blood pressure readings, and a self-reported health questionnaire. All individuals who were later diagnosed with TAAs or AAAs were identified. Age, sex, and time-matched controls were selected from the same cohorts, aiming at four controls/case. Adjusted odds ratios (aORs) for potential risk factors for later diagnosis of TAAs and AAAs, respectively, were estimated by multivariate conditional logistic regression analyses.

RESULTS

From a total of 96,196 individuals with prospectively collected data in the VIP/MONICA cohort, a total of 236 individuals with AAAs (181 men and 55 women) and 935 matched controls, and 168 individuals with TAAs (115 men and 53 women) and 662 controls were included. The average age at baseline examination was 57.0 ± 5.7 years for AAA cases and controls, and 52.1 ± 8.8 years for TAA cases and controls. Mean time between baseline examination and diagnosis of AAAs/TAAs was 12.1 and 11.7 years, respectively. There was a clear difference in risk factor profile between AAAs and TAAs. Smoking, hypertension, and coronary artery disease were significantly associated with later diagnosis of AAAs, with highest aORs for a history of smoking (aOR, 10.3; 95% confidence interval [CI], 6.3-16.8). For TAAs, hypertension was the only positive risk factor (aOR, 1.7; 95% CI, 1.1-2.7), whereas smoking was not associated. Diabetes was not associated with either AAAs or TAAs; neither was self-reported physical activity.

CONCLUSIONS

In this prospective, population-based, case-control study, risk factor profile differed between AAAs and TAAs. This suggests a partially different etiology for TAAs and AAAs.

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.

Sex and Gender Differences in Aortic Disease

Dilatation of the thoracic or abdominal aorta can progress to dissection or rupture with significant associated morbidity and mortality. Aortic disease remains a treatable contributor to mortality in the US and its burden is likely underestimated. Recent clinical studies have uncovered sex and gender distinctions in the epidemiology, pathophysiology, and outcomes of aortic disease. Despite this, there has been little progress in the application of these findings to clinical practice. Improved understanding of the sex-specific mechanisms of aortic disease may inform personalized indications for elective repair and thus reduce the morbidity of aortic catastrophe. The objective of this review is to summarize known clinical and biological sex differences in both thoracic and abdominal aortic disease and highlight promising areas for future investigation.

Gender-specific Predicted Normal Aortic Size and Its Consequences of the Population-Based Prevalence of Abdominal Aortic Aneurysms

BACKGROUND

To investigate if a relative-size-index of the abdominal aortic diameter influences the prevalence estimates of abdominal aortic dilatations compared to absolute diameters.

METHODS

Cross-sectional study. Participants from the Viborg Vascular Screening Trial, Viborg Women Cohort, and the Viborg Screening Program. Through multivariate linear regression analyses, 2 gender-specific prediction-equations were developed based upon body-surface area and age. The definitions of absolute and relative size of aortic ectasies were 25-29 mm and 1.25-1.49× individual-predicted size (IPS), abdominal aortic aneurysm (AAA) 30 mm and 1.5× IPS, and large repair-recommendable AAA ≥55 mm or ≥ 2.75× IPS, respectively.

RESULTS

Nineteen thousand two hundred and sixty nine males (69.6 years) and 2,426 females (67.1 years) attended the population- and ultrasound-based screening studies for AAA. The mean peak systolic abdominal anterior-posterior inner to inner diameter was 19.1 mm (±5.3 mm) and 16.6 mm (±2.8 mm) (P < 0.001) in males and females, respectively. Body surface area showed the strongest correlation with aortic diameters in both males (r = 0.19, P < 0.001) and females (r = 0.17, P < 0.001). Age correlated significantly with size, but only in males (r = 0.03, P < 0.001). The prevalence in men of absolute size-defined and relative size index-defined screening-detected aortic ectasies, AAAs and repair-recommendable AAAs were: 5.9% and 9.5% (P < 0.001), 3.3% and 4.2% (P < 0.001) and 9.9% and 15.2% (P = 0.004), respectively. Prevalence in females of absolute-size-defined and relative-size-index-defined screening-detected aortic ectasies, AAAs and repair-recommendable AAAs were 1.2% and 5.8% (P < 0.001), 0.5% and 1.3% (P = 0.003) and 0.0% and 23.1% (P = 0.553), respectively.

CONCLUSIONS

Despite statistical differences, ultrasound-based absolute diameters to detect AAA seem acceptable in men. In females, poor agreements were noticed concerning all 3 categories of aneurysms, indicating that the current absolute diagnostic cut-points do not reflect female anatomy.

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.

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.

Vitamin D as A Protector of Arterial Health: Potential Role in Peripheral Arterial Disease Formation

Atherosclerotic occlusive diseases and aneurysms that affect large and medium-sized arteries outside the cardiac and cerebral circulation are collectively known as peripheral arterial disease (PAD). With a rise in the rate of aging population worldwide, the number of people diagnosed with PAD is rapidly increasing. The micronutrient vitamin D is an important steroid hormone that acts on many crucial cellular mechanisms. Experimental studies suggest that optimal levels of vitamin D have beneficial effects on the heart and blood vessels; however, high vitamin D concentrations have been implicated in promoting vascular calcification and arterial stiffness. Observations from various clinical studies shows that deficiency of vitamin D has been associated with a greater risk of PAD. Epidemiological studies have often reported an inverse relation between circulating vitamin D status measured in terms of 25-hydroxivitamin D [25(OH)D] levels and increased cardiovascular disease risk; however, randomized controlled trials did not show a consistent positive effect of vitamin D supplementation on cardiovascular disease risk or events. Even though PAD shares all the major risk factors with cardiovascular diseases, the effect of vitamin D deficiency in PAD is not clear. Current evidence suggests a strong role of vitamin D in promoting genomic and epigenomic changes. This review summarises the current literature that supports the notion that vitamin D deficiency may promote PAD formation. A better understanding of underlying pathological mechanisms will open up new therapeutic possibilities which is the main unmet need in PAD management. Furthermore, epigenetic evidence shows that a more holistic approach towards PAD prevention that incorporates a healthy lifestyle, adequate exercise and optimal nutrition may be more effective in protecting the genome and maintaining a healthy vasculature.

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.

Screening women aged 65 years or over for abdominal aortic aneurysm: a modelling study and health economic evaluation

BACKGROUND

Abdominal aortic aneurysm (AAA) screening programmes have been established for men in the UK to reduce deaths from AAA rupture. Whether or not screening should be extended to women is uncertain.

OBJECTIVE

To evaluate the cost-effectiveness of population screening for AAAs in women and compare a range of screening options.

DESIGN

A discrete event simulation (DES) model was developed to provide a clinically realistic model of screening, surveillance, and elective and emergency AAA repair operations. Input parameters specifically for women were employed. The model was run for 10 million women, with parameter uncertainty addressed by probabilistic and deterministic sensitivity analyses.

SETTING

Population screening in the UK.

PARTICIPANTS

Women aged ≥ 65 years, followed up to the age of 95 years.

INTERVENTIONS

Invitation to ultrasound screening, followed by surveillance for small AAAs and elective surgical repair for large AAAs.

MAIN OUTCOME MEASURES

Number of operations undertaken, AAA-related mortality, quality-adjusted life-years (QALYs), NHS costs and cost-effectiveness with annual discounting.

DATA SOURCES

AAA surveillance data, National Vascular Registry, Hospital Episode Statistics, trials of elective and emergency AAA surgery, and the NHS Abdominal Aortic Aneurysm Screening Programme (NAAASP).

REVIEW METHODS

Systematic reviews of AAA prevalence and, for elective operations, suitability for endovascular aneurysm repair, non-intervention rates, operative mortality and literature reviews for other parameters.

RESULTS

The prevalence of AAAs (aortic diameter of ≥ 3.0 cm) was estimated as 0.43% in women aged 65 years and 1.15% at age 75 years. The corresponding attendance rates following invitation to screening were estimated as 73% and 62%, respectively. The base-case model adopted the same age at screening (65 years), definition of an AAA (diameter of ≥ 3.0 cm), surveillance intervals (1 year for AAAs with diameter of 3.0-4.4 cm, 3 months for AAAs with diameter of 4.5-5.4 cm) and AAA diameter for consideration of surgery (5.5 cm) as in NAAASP for men. Per woman invited to screening, the estimated gain in QALYs was 0.00110, and the incremental cost was £33.99. This gave an incremental cost-effectiveness ratio (ICER) of £31,000 per QALY gained. The corresponding incremental net monetary benefit at a threshold of £20,000 per QALY gained was -£12.03 (95% uncertainty interval -£27.88 to £22.12). Almost no sensitivity analyses brought the ICER below £20,000 per QALY gained; an exception was doubling the AAA prevalence to 0.86%, which resulted in an ICER of £13,000. Alternative screening options (increasing the screening age to 70 years, lowering the threshold for considering surgery to diameters of 5.0 cm or 4.5 cm, lowering the diameter defining an AAA in women to 2.5 cm and lengthening the surveillance intervals for the smallest AAAs) did not bring the ICER below £20,000 per QALY gained when considered either singly or in combination.

LIMITATIONS

The model for women was not directly validated against empirical data. Some parameters were poorly estimated, potentially lacking relevance or unavailable for women.

CONCLUSION

The accepted criteria for a population-based AAA screening programme in women are not currently met.

FUTURE WORK

A large-scale study is needed of the exact aortic size distribution for women screened at relevant ages. The DES model can be adapted to evaluate screening options in men.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015020444 and CRD42016043227.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Correcting for Body Surface Area Identifies the True Prevalence of Abdominal Aortic Aneurysm in Screened Women

OBJECTIVE

Recently, the prevalence of abdominal aortic aneurysm (AAA) using screening strategies based on elevated cardiovascular disease (CVD) risk was reported. AAA was defined as a diameter ≥30 mm, with prevalence of 6.1% and 1.8% in men and women respectively, consistent with the widely reported AAA predominant prevalence in males. Given the obvious differences in body size between sexes this study aimed to re-evaluate the expanded CVD risk based AAA screening dataset to determine the effect of body size on sex specific AAA prevalence.

METHODS

Absolute (26 and 30 mm) and relative (aortic size index [ASI] equals the maximum infrarenal aorta diameter (cm) divided by body surface area (m²), ASI ≥ 1.5) thresholds were used to assess targeted AAA screening groups (n = 4115) and compared with a self reported healthy elderly control group (n = 800).

RESULTS

Male AAA prevalence was the same using either the 30 mm or ASI ≥1.5 aneurysm definitions (5.7%). In females, AAA prevalence was significantly different between the 30 mm (2.4%) and ASI ≥ 1.5 (4.5%) or the 26 mm (4.4%) thresholds.

CONCLUSION

The results suggest the purported male predominance in AAA prevalence is primarily an artefact of body size differences. When aortic size is adjusted for body surface area there is only a modest sex difference in AAA prevalence. This observation has potential implications in the context of the ongoing discussion regarding AAA screening in women.

Analysis of the Correlation Between Central Obesity and Abdominal Aortic Diseases

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

An association of spleen volume and aortic diameter in patients and in mice with abdominal aortic aneurysm

Background

To investigate the potential mechanism of splenic enlargement in Ang II/APOE model and the associations between the spleen volume and the indices of abdominal aortic aneurysm (AAA) in human.

Methods

To investigate the changes of spleen volume on AAA formation, apolipoprotein E knockout (Apo E^−/−) mice were treated with Ang II (1000 ng/kg/min) up to 28 days to generate AAA. We used Magnetic Resonance Imaging (MRI), liquid measurement, H&E and immunohistochemistry to analyze the morphological or pathological changes of spleen. To investigate the changes of spleen volume in human, a retrospective case-control study involving 30 male AAA patients and 25 male controls were performed. Spleen volume was measured on computed tomography images. Univariate analysis and multivariable sequential logistic regression analyses were used to analyze the association between spleen volume and maximal diameter (Dmax).

Results

In Ang II/APOE model, we found splenic enlargement in mice with AAA compared with the sham group. Histopathological investigations revealed hypertrophies of splenic follicles and increased populations of CD3⁺ T cells. In clinic cohort study, univariate analysis revealed higher values in large AAA (Dmax > 5.5 cm,n = 15) compared with the small (Dmax < 5.5 cm,n = 15) for spleen volume (230.6 ± 64.5 cm³ vs. 170.0 ± 32.8 cm³; P = 0.0030). Regression analysis revealed a statistically significant positive linear correlation of spleen volume and Dmax of AAA (r = 0.3611;P = 0.0423).

Conclusions

Mimicking the splenic pathology observed in murine AAA model, there is a strong positive correlation between spleen volume and the Dmax in male AAA patients. As Dmax is a valuable predictor of AAA rupture, the spleen enlargement may be another indicator.

Screening of siblings to patients with abdominal aortic aneurysms in Sweden

OBJECTIVE

The prevalence of Abdominal Aortic Aneurysm (AAA) is higher for First Degree Relatives to AAA-patients compared to the general population, regardless of sex. The prevalence of AAA is also higher in the North of Sweden compared to the Mid and South. A regional strong hereditary trait has been suggested as an explanation to this. The aim of this study was to investigate if siblings to AAA-patients in the North have a higher prevalence of AAA compared to siblings in the Mid-region.

DESIGN

Cohort study.

MATERIALS AND METHODS

All patients treated for AAA in a northern region (Norrbotten county, North) were screened for siblings. Consenting siblings, age 40-80, were examined (n = 379) with ultrasound. The results were compared to the previously published results of 150 ultrasound-screened siblings in the Mid-region (Stockholm county).

RESULTS

The male/female ratio in the sibling cohort was 48% vs 52%. The prevalence of AAA in siblings in the North was 37/379 (brothers 14%, sisters 6%). This was not different from the prevalence among the Mid-region siblings 16/150 (brothers 17%, sisters 6% (p = 0.75). The distribution of risk factors was similar in the two regions.

CONCLUSION

The results reinforce the importance of a more systematic approach towards selective screening of all siblings to AAA patients. Ultrasound should be performed in all eligible siblings, since the distribution of AAA is similar over regions. A correlation between the familial distribution and the reported high prevalence of AAA in general population in the North could not be shown.

Associations of ApoAI and ApoB-containing lipoproteins with AngII-induced abdominal aortic aneurysms in mice

OBJECTIVE

Dyslipidemia is implicated in abdominal aortic aneurysms (AAAs) in humans and angiotensin (Ang) II-infused mice. This study determined effects of major lipoprotein classes on AngII-induced AAAs using multiple mouse strains with dietary and pharmacological manipulations.

APPROACH AND RESULTS

Western diet had minor effects on plasma cholesterol concentrations and the low incidence of AngII-induced AAAs in C57BL/6J mice. Low incidence of AAAs in this strain was not attributed to protection from high-density lipoprotein, because apolipoprotein (apo) AI deficiency did not increase AngII-induced AAAs. ApoAI deletion also failed to alter AAA occurrence in hypercholesterolemic mice. Low-density lipoprotein receptor-/- mice fed normal diet had low incidence of AngII-induced AAAs. Western diet feeding of this strain provoked pronounced hypercholesterolemia because of increased apoB-containing lipoproteins with attendant increases of atherosclerosis in both sexes, but AAAs only in male mice. ApoE-deficient mice fed normal diet were modestly hypercholesterolemic, whereas this strain fed Western diet was severely hypercholesterolemic because of increased apoB-containing lipoprotein concentrations. The latter augmented atherosclerosis, but did not change the high incidence of AAAs in this strain. To determine whether reductions in apoB-containing lipoproteins influenced AngII-induced AAAs, ezetimibe was administered at a dose that partially reduced plasma cholesterol concentrations to ApoE-deficient mice fed Western diet. This decreased atherosclerosis, but not AAAs. This ezetimibe dose in ApoE-deficient mice fed normal diet significantly decreased plasma apoB-containing lipoprotein concentrations and reduced AngII-induced AAAs.

CONCLUSIONS

ApoB-containing lipoproteins contribute to augmentation of AngII-induced AAA in male mice. However, unlike atherosclerosis, AAA occurrence was not correlated with increases in plasma apoB-containing lipoprotein concentrations.

[Review of pre- and post-treatment multidetector computed tomography findings in abdominal aortic aneurysms]

The increase in the frequency of abdominal aortic aneurysms (AAA) and the widely accepted use of endovascular aneurysm repair (EVAR) as a first-line treatment or as an alternative to conventional surgery make it necessary for radiologists to have thorough knowledge of the pre- and post-treatment findings. The high image quality provided by multidetector computed tomography (MDCT) enables CT angiography to play a fundamental role in the study of AAA and in planning treatment. The objective of this article is to review the cases of AAA in which CT angiography was the main imaging technique, so that radiologists will be able to detect the signs related to this disease, to diagnose it, to plan treatment, and to detect complications in the postoperative period.

Current prevalence of abdominal aortic aneurysm in 70-year-old women

BACKGROUND

Screening elderly men for abdominal aortic aneurysm (AAA) to reduce mortality from rupture is evidence-based. For women epidemiological data on AAA are scarce, and the evidence for screening is insufficient. The aim of this population-based study was to determine the current prevalence of AAA and risk factors among 70-year-old women.

METHODS

All 70-year-old women identified through the National Population Registry in the two neighbouring counties of Uppsala and Dalarna were invited to a free ultrasound examination of the abdominal aorta. An AAA was defined as a maximum infrarenal aortic diameter of at least 30 mm.

RESULTS

Of 6925 women invited, 5140 (74·2 per cent) accepted the invitation to be screened. Among these, 19 AAAs were detected (0·4 (95 per cent confidence interval (c.i.) 0·2 to 0·5) per cent). In the invited cohort 12 women (0·2 (0·1 to 0·3) per cent) had undergone previous AAA repair (11) or had a known AAA under surveillance (1). Thus, the total prevalence was estimated at 0·5 (0·4 to 0·7) per cent. Smoking was strongly associated with AAA; 18 (95 per cent) of 19 women with a screen-detected AAA had a history of smoking compared with 44·2 per cent of those with a normal aorta (odds ratio 20·29, 95 per cent c.i. 2·70 to 152·65). The prevalence of AAA was 0·03 (0 to 0·1) per cent among never smokers, 0·4 (0·2 to 0·8) per cent among former smokers and 2·1 (1·0 to 3·7) per cent among current smokers.

CONCLUSION

Screening 70-year-old women who do not smoke is likely to be futile, thus ruling out population screening of women for AAA.

The association between serological markers for Chlamydophila pneumoniae and the development of abdominal aortic aneurysm

BACKGROUND

To investigate the association between serological markers for Chlamydophila pneumoniae (Cpn) and the development of abdominal aortic aneurysm (AAA) in a population-based case-control study.

METHODS

A screening for AAA among 65-75-year-old men and women was performed in a population with high prevalence of disease. Most of the subjects had undergone previous testing at the age of 60, including blood sampling. A total of 42 patients with AAA were compared with 100 age- and gender-matched controls with normal aortas. Cpn immunoglobulin A (IgA) and immunoglobulin G (IgG) antibodies present in plasma samples obtained at the time of screening (current) and in the past 5-15 (mean, 12) years (historical) were analyzed. Cpn antibody titers (<1/64, 1/64, 1/264, and 1/1024) were analyzed using the microimmunofluorescence technique.

RESULTS

No differences in current Cpn immunoglobulin A and IgG antibodies titers (p = 0.111 and 0.659), historical titers (p = 0.449 and 0.228), or titer change (delta) (p = 0.794 and 0.172) were observed between patients with AAA and controls. In all, 82% of the patients with AAA had a current Cpn IgG titer of 1/1024 as compared with the 70% of the control group. All 11 patients who had an aortic diameter of >40 mm reported having high current Cpn IgG titers. The fact that such a large proportion of the healthy population demonstrated an immune response against Cpn made it difficult to demonstrate possible effects of Cpn infection on AAA formation in a case-control study.

CONCLUSION

No significant associations were found between AAA detected by screening and Cpn antibody titer levels at the time of screening or during past screening at the age of 60.

Aneurysms--from traumatology to screening

This paper deals with aneurysmal disease, primarily when localized in the abdominal aorta. It is based on the Olof Rudbeck lecture 2009. Aneurysm is a localized widening of an artery, and its definition has become an important issue today when the disease is in focus for screening programmes. Aetiology and pathogenesis are still poorly understood, but a genetic component determining the strength of the aortic wall is important, and there is a strong male dominance. Historically, several attempts have been made to treat the disease, but reconstructive treatment has been possible only since 1951, in an increasing number of cases performed endovascularly. By early detection through screening, and thereby the possibility to treat before rupture, it has now become possible to decrease the total mortality from the disease in the population.

How to Define an Abdominal Aortic Aneurysm — Influence on Epidemiology and Clinical Practice

Abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta. There is, however, no general agreement on how to define an AAA. The lack of a uniform definition may have consequences on epidemiology and clinical practice. Several proposed definitions of an AAA exist, all based on the diameter of the abdominal aorta. Age, gender, and body size are all associated with the aortic diameter, and may therefore also be of importance when evaluating the aortic diameter. The precision of the measurement and the awareness of imaging shortcomings are also important. In order to demonstrate a true widening of the aorta the relation to adjacent aortic segments must be assessed. To demonstrate an expansion of a potential aneurysm, a follow-up period with repeated assessments is required. Thus, a fixed diameter does not serve as a proper definition of an aneurysm, but rather as a cut-off level for further assessment and/or follow-up.

Abdominal aortic aneurysm--to screen or not to screen

With the ten WHO criteria for a screening program to be started, screening for abdominal aortic aneurysm is analyzed. Most of the criteria are fulfilled concerning the 65-year old male population, whereas concerning females we need more knowledge. Still the aneurysmal diameter is the most important factor to select patients for treatment meaning that many aneurysms are treated where rupture should never have occurred. Research projects giving more information on pathophysiological processes behind expansion and rupture should have priority.

Elevated tissue plasminogen activator in patients with screening-detected abdominal aortic aneurysm

OBJECTIVE

A population-based case-control study with historical and current data was conducted in a population with a high prevalence of disease to explore the hypothesis that the fibrinolytic system may be involved in the early pathogenesis of abdominal aortic aneurysm (AAA).

METHODS

Forty-two patients found to have AAA at population-based screening were compared with 100 controls matched for age and sex. Mass concentration of tissue plasminogen activator (tPA mass) and tissue plasminogen activator/plasminogen activator inhibitor-1 complex (tPA/PAI-1 complex mass) were analyzed in blood samples obtained at the screening (current), and in blood samples obtained from a study conducted 12 years previously on the same population (historical).

RESULTS

Current tPA mass levels were significantly higher in AAA patients compared with controls (13.6 vs 11.4 microg/L, P=.016). A similar trend was observed in historical tPA mass levels (9.8 vs 8.2 microg/L, P=.062). Current and historical mass concentrations of tPA/PAI complex in AAA patients were similar to those in controls. Current tPA mass levels retained the associations with AAA in a logistic regression model after adjustment for history of atherosclerosis (odds ratio [OR], 1.1 per microg/L, P=.039) and current smoking (OR 1.1 per microg/L, P=.039). When family history of AAA was added in a logistic regression model, the OR for current tPA mass was 1.1 per microg/L (P=.056) and 1.1 per microg/L (P=.070) when treated hypertension was added.

CONCLUSION

The finding of elevated tPA mass, in contrast to tPA/PAI-1 complex, in plasma among patients with screening-detected AAA supports the hypothesis that the fibrinolytic system may be important in the early pathogenesis of AAA.

Diagnosis of an aneurysm masquerading as a pancreatic-cyst lesion at EUS

BACKGROUND

EUS-guided FNA is commonly performed for evaluating pancreatic-cyst lesions. However, not all such lesions are true cystic neoplasms of the pancreas.

OBJECTIVE

Determine the frequency at which aneurysms mimicking cysts are encountered during EUS evaluation of the pancreas.

STUDY DESIGN

Observational study.

SETTING

Tertiary referral center.

PATIENTS

Consecutive patients found to have pancreatic cyst lesions at EUS.

INTERVENTIONS

Patients with a cyst lesion in the pancreas that was suspicious for an aneurysm at EUS underwent abdominal CT imaging for a definitive diagnosis.

MAIN OUTCOME MEASURES

To determine the frequency at which aneurysms are encountered during EUS while evaluating pancreatic-cyst lesions and to describe the EUS characteristics of an underlying aneurysm.

RESULTS

Four of 413 lesions (0.97%, 95% confidence interval 0.26%-2.5%) that appeared as pancreatic cysts at EUS were diagnosed to be aneurysms: 2 were splenic artery aneurysms, 1 was an aneurysm of the gastroduodenal artery, and another was an infrarenal aortic aneurysm. The aneurysms had a characteristic donut-like appearance at EUS: a thick outer wall with a central anechoic area.

LIMITATIONS

Observational study; small sample size.

CONCLUSIONS

Aneurysms can masquerade as pancreatic-cystic lesions. Awareness of this entity is important because an inadvertent FNA during EUS may potentially lead to serious complications.

Cost-effectiveness of screening women for abdominal aortic aneurysm

BACKGROUND

Women are usually not considered for abdominal aortic aneurysm (AAA) screening because of their lower prevalence of disease. This position may, however, be questioned given the higher risk of rupture and the longer life expectancy among women. The purpose of this study was to assess the cost-effectiveness of screening 65-year-old women for AAA.

METHODS

A systematic review of the literature was conducted to obtain data of importance to evaluate the effectiveness of screening women for AAA. Data were entered into a Markov simulation cohort model.

RESULTS

The review suggested some main assumptions for women with AAA. Prevalence is 1.1%. In 6.8%, the AAA is of a size that merits surgery, and the patients are fit for a procedure. For patients with an AAA, the yearly risk for elective surgery and the rupture incidence was 3.1% and 2.4%, respectively, in the invited group and 1.1% and 5.7% in the noninvited group. The operative mortality for elective surgery was 3.5%, and the total mortality for ruptured AAA was 86.3%. The long-term mortality for AAA patients was 3.6 times higher than for an age-matched healthy population. Screening reduced the AAA rupture incidence by 33% and the AAA-related death rate by 35%. The cost per life year gained was estimated at $5911.

CONCLUSION

The incremental cost-effectiveness ratio was similar to that found for screening men, which reflects the fact that the lower AAA prevalence in women is balanced by a higher rupture rate. Screening women for AAA may be cost-effective, and future evaluations on screening for AAA should include women.

Detection of Abdominal Aortic Aneurysm in Patients with Peripheral Artery Disease

OBJECTIVE

To describe the prevalence of abdominal aortic aneurysms (AAA) in patients with peripheral artery disease (PAD).

DESIGN

Observational, descriptive, transverse study.

PATIENTS AND METHODS

We performed an abdominal ultrasound in 1190 consecutive patients with lower limb chronic ischemia (1/99-12/04). We registered cardiovascular risk factors and clinical data for analysis.

RESULTS

The ultrasound was inconclusive in 24 (2%) patients; 1166 patients completed the study. They were mostly male (93.7%), with an age mean of 67+/-9.9 years (37.7-93.4). The main cardiovascular risk factors were: smoking (80.9%), hypertension (41.7%) and hypercholesterolemia (31.4%). The prevalence of AAA was 13% (n = 151). Only 1.5% (n = 17) of the patients had a large AAA (>5 cm). The AAA was clearly more prevalent in men (n = 148; 13.6%) than in women (n = 3; 4.1%) (RR 3.47; 95% CI 1.11-10.89; p = 0.02). The prevalence significantly increased with age, with a maximum of 17.1% in over 75-year-old men (p = 0.006). Patients with tibial disease had a significantly higher prevalence of AAA than aortoiliac or femoro-popliteal disease (p = 0.02).

CONCLUSIONS

The prevalence of AAA in patients with PAD is much higher than that reported in the general population. We recommend that an abdominal ultrasound be routinely included in the study of these patients. Over 75-year-old men are at particularly high-risk.