Abdominal Aortic Aneurysm Growth Rate Research Articles

Alcohol Intake and Growth Rate of Abdominal Aortic Aneurysms in Men- results of a Prospective Population-based Randomised Screening Trial with up to Five Year Follow-up

Introduction: Abdominal aortic aneurysm (AAA) is a common disease with a pathological dilatation of the aortic wall, and the prevalence is up to 2% people above 50 years. Age, smoking, male sex, family history of AAA, and hypertension are known risk factors for developing AAAs. Recent studies suggested that moderate intake of alcohol was associated with a lower hazard rate of developing AAA. No studies have reported how alcohol affects the growth rate of AAAs. Therefore, the aim of this study was to investigate the association between alcohol intake and growth rate of AAAs. Methods: This study was based on data from VIVA, a population-based randomised screening trial of men aged 65-74 enrolling from October 2008 until July 2011. Study participants were randomly assigned 1:1 to screening or no screening. Lifestyle parameters, medical history and use of medication were self-reported. Ultrasound scans of the infrarenal abdominal aorta were performed by specially trained nurses, the maximal systolic inner-to-inner anterior-posterior diameter was measured. Ultrasound surveillance was annual and continued up to five years. Results: Analysing the association between the aneurysmal growth rate and intake of alcohol, we found in our crude analysis that an increase by one daily unit of alcohol intake increased the growth rate by 3.5% (estimate 1.035, CI 0.99-1.08). After adjusting for potential confounders, we found that an increase by one daily unit of alcohol increased the aneurysmal growth rate by 2.3% (estimate 1.023, Cl 0.98-1.07). Analysing the need for repair as a time-to-event analysis, we found in our crude analysis, that an increase by one unit of alcohol changed the hazard ratio by 1.08 (CI 0.99-1.17). In our adjusted analysis, we found a similar result of one unit of alcohol increasing the hazard ratio by 1.07 (Cl 0.98-1.17). Conclusion: Although no statistically significant associations were exposed, a constant trend for adjusted positive associations between alcohol intake and the natural history of AAA was noticed calling for clarifying larger studies or meta-analyses. Disclosure: Nothing to disclose

Peroxynitrite Footprint in Circulating Neutrophils of Abdominal Aortic Aneurysm Patients is Lower in Statin than in Non-Statin Users

Introduction - Extensive reactive oxygen and nitrogen species (ROS/RNS, also reactive species) production is a mechanism involved in abdominal aortic aneurysm (AAA) development.1 White blood cells (WBC) are a known source of reactive species.2 Its production is possibly decreased by statins, thereby reducing AAA growth rate.3 We investigated reactive species production in circulating WBC of AAA patients and the effect of statins on its production.

Plasma D-dimer as a predictor of intraluminal thrombus burden and progression of abdominal aortic aneurysm

AimIntraluminal thrombus (ILT) is presented in most abdominal aortic aneurysms (AAAs) and is suggested to promote AAA expansion. D-dimer, a breakdown product in the thrombus remodeling, may have prognostic value for AAA. This study investigated the interrelation between plasma D-dimer level, ILT volume, AAA size and progression. Main methodsThis was a retrospective observational study that involved 181 patients with infra-renal AAA. They were divided into small and large AAA groups according to AAA diameter. 24 of them had repeated abdominal computed tomography angiography (CTA) scan and were divided into slow-growing and fast-growing AAA groups according to the median value of AAA growth rate. Baseline and follow-up plasma D-dimer level, maximum diameter of AAA, total infra-renal aortic volume and ILT volume were analyzed. Key findingsPlasma D-dimer level was positively correlated with ILT volume (R = 0.382, P < 0.001) and maximum diameter of AAA (R = 0.442, P < 0.001). Increasing value of plasma D-dimer was positively associated with the accelerated growth rate of AAA (R = 0.720, P < 0.01). ILT volume showed positive correlation with maximum diameter (R = 0.859, P < 0.001) and growth rate of AAA (R = 0.490, P < 0.05). After adjusting the baseline ILT volume, the positive correlations remained to be statistically significant between plasma D-dimer level and AAA size (R = 0.200, P < 0.05), as well as increasing value of plasma D-dimer and growth rate of AAA (R = 0.642, P < 0.05). SignificancePlasma D-dimer level reflected ILT burden in AAAs. Plasma D-dimer level and ILT volume were positively correlated with AAA size. Increasing value of plasma D-dimer and baseline ILT volume could be predictors of AAA progression.

Meta-analysis of the growth rates of abdominal aortic aneurysm in the Chinese population

BackgroundSeveral studies on the growth rates of abdominal aortic aneurysm (AAA) in Chinese population have been conducted; however, this issue remains unclear. The aim of this study is to systematically review published data of the AAA growth rates among people in China.MethodsWe conducted a comprehensive search of multiple databases to identify all studies of AAA growth in the Chinese population from inception until June 2017. AAA growth rates were combined to yield the growth rates at specified aneurysm diameter ranges, with using a random-effects model or fixed-effects model according to heterogeneity.ResultsA total of 8257 studies were initially identified and only 4 studies were eventually included. A random-effects analysis showed that the growth rates of AAA in Chinses population is ranging from 0.18 cm/year to 0.75 cm/year. The pooled mean growth rates among individuals with aneurysm measuring 3.0–3.9 cm, 4.0–5.9 cm and ≧ 6.0 cm in diameter were 0.21 cm/year (95% CI: 0.19 cm/year to 0.23 cm/year), 0.38 cm/year (95% CI: 0.33 cm/year to 0.43 cm/year), and 0.71 cm/year (95% CI: 0.64 cm/year to 0.77 cm/year) respectively. Further analysis found that the pooled mean growth rates for individuals with small AAA (diameters measuring 3.0–4.9 cm) was 0.28 cm/year (95% CI: − 0.06 cm/year to 0.61 cm/year)`and for individuals with large AAA (diameters ≥5.0 cm) was 0.75 cm/year (95% CI: 0.20 cm/year to 1.3 cm/year). Finally, meta-regression showed a strong trend of linear relationship between AAA growth rate and aneurysm diameter.ConclusionsThe growth rates of AAA in the Chinese population increase with AAA enlargement and appear to range from 0.18 cm/year in the smallest AAAs to 0.75 cm/year when the diameter exceeds 6 cm. However, based on current studies, it is difficult to estimate the accurate average AAA growth rate in Chinese patients. More large-scale, high-quality studies are required to achieve that. Overall, AAA growth rate increase with increased aneurysm diameter.

Diabetes and Its Effect on Abdominal Aortic Aneurysm Growth Rate in Hispanic Patients

The growth rate of abdominal aortic aneurysms (AAA) can vary depending on age, baseline diameter, blood pressure, race, and history of smoking. Paradoxically, previous studies show evidence of a protective effect of diabetes on the rate of AAA expansion despite its well-established role in the morbidity and mortality of cardiovascular disease. This study aims to investigate the impact diabetes plays on AAA growth within a Hispanic population. Data were collected from patients who were predominantly Mexican-American at a single hospital site. Baseline and follow-up measures for AAA diameter were obtained from serial imaging studies. Demographics, medical history, the presence of type 2 diabetes, and medication use were extracted from hospital records. Linear mixed-effects growth models were used to calculate the overall AAA growth rate and to assess the difference in AAA growth rate between demographics, comorbidities, and medication use. The study comprised 201 patients (70.4% male) with a mean baseline age of 79.1years, of whom 43.2% were diabetic. The average monthly AAA growth rate across all study participants was 0.15mm (SE=0.02mm). Independently, the average AAA expansion rate for the diabetic and nondiabetic groups was 0.07mm (SE=0.04mm) and 0.21mm (SE=0.03mm) per month, respectively. This demonstrates a 65% lower linear AAA expansion rate per month in patients with diabetes. This study confirms a difference of AAA physiology between diabetics and nondiabetics in the Hispanic community. The observed significant difference in AAA growth rate may be a combination of factors associated with race/ethnicity, prevalence of diabetes mellitus, and low compliance with diabetic control exhibited in the Mexican-American population.

Statins Reduce Abdominal Aortic Aneurysm Growth, Rupture, and Perioperative Mortality: A Systemic Review and Meta-Analysis

This study is a retrospective review of Cochrane CENTRAL database, MEDLINE, and Embase through June 15, 2018. Analysis of 22 studies involving 80,428 patients with abdominal aortic aneurysms (AAAs) revealed that statin use is associated with a mean AAA growth rate reduction of 0.82 mm/y (P = .001), lower rupture risk (P < .0001), and lower 30-day mortality after elective AAA repair (P = .005). The crude rupture rate was 34% for statin patients and 47% for control patients. The crude 30-day mortality rate was 1.8% for the statin group and 2.6% for the control group. The largest effect was in patients who underwent open AAA repair as opposed to endovascular aneurysm repair. Statin use may be associated with reduction in AAA growth, rupture, and perioperative mortality after elective AAA repair.

Evaluation of the distribution and progression of intraluminal thrombus in abdominal aortic aneurysms using high-resolution MRI.

Intraluminal thrombus (ILT) signal intensity on MRI has been studied as a potential marker of abdominal aortic aneurysm (AAA) progression. 1) To characterize the relationship between ILT signal intensity and AAA diameter; 2) to evaluate ILT change over time; and 3) to assess the relationship between ILT features and AAA growth. Prospective. Eighty AAA patients were imaged, and a subset (n = 41) were followed with repeated MRI for 16 ± 9 months. 3D black-blood fast-spin-echo sequence at 3 T. ILT was designated as "bright" if the signal was greater than 1.2 times that of adjacent psoas muscle. AAAs were divided into three groups based on ILT: Type 1: bright ILT; Type 2: isointense ILT; Type 3: no ILT. During follow-up, an active ILT change was defined as new ILT formation or an increase in ILT signal intensity to bright; stable ILT was defined as no change in ILT type or ILT became isointense from bright previously. Shapiro-Wilk test; Mann-Whitney U-test; Fisher's exact test; Kruskal-Wallis test; Spearman's r; intraclass correlation coefficient (ICC), Cohen's kappa. AAAs with Type 1 ILT were larger than those with Types 2 and 3 ILT (5.1 ± 1.1 cm, 4.4 ± 0.9 cm, 4.2 ± 0.8 cm, P = 0.008). The growth rate of AAAs with Type 1 ILT was significantly greater than that of AAAs with Types 2 and 3 ILT (2.6 ± 2.5, 0.6 ± 1.3, 1.5 ± 0.6 mm/year, P = 0.01). During follow-up, AAAs with active ILT changes had a 3-fold increased growth rate compared with AAAs with stable ILT (3.6 ± 3.0 mm/year vs. 1.2 ± 1.5 mm/year, P = 0.008). AAAs with bright ILT are larger in diameter and grow faster. Active ILT change is associated with faster AAA growth. Black-blood MRI can characterize ILT features and monitor their change over time, which may provide new insights into AAA risk assessment. 2 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:994-1001.

Aortic sac enlargement after endovascular aneurysm repair: volume-related changes and the impact of intraluminal thrombus.

PurposeAbdominal aortic aneurysm (AAA) growth after endovascular aneurysm repair (EVAR) is still unpredictable. The issue of optimal frequency of computed tomography angiography for surveillance and its measurement method accuracy remain unclear. We aimed to assess the value of abdominal aneurysm sac volume measurement for detecting expansions and the association of preprocedural intraluminal thrombus (ILT) volume with aneurysm sac growth following EVAR.Material and methodsA total of 107 patients underwent elective EVAR. Inclusion criteria provided a cohort of 39 patients. Changes of postoperative maximum aneurysm sac diameter and AAA volume were calculated. Volumetric AAA changes and demographic data of the cases with clinically irrelevant AAA diameter enlargement were evaluated. Preoperative ILT volumes were collected. ILT and AAA sac volume ratio was calculated. Statistical data analysis was performed using standard methods.ResultsThe mean changes of maximum AAA diameter and volume in percentage after EVAR were –5.08 ± 8.20 mm and –13.39 ± 23.32%, respectively. A moderate positive linear correlation between those changes was found (R 2 = 0.731; p < 0.0001). The mean relative AAA volume increase in cases without clinically relevant diameter enlargement was 11.50 ± 8.27%. The means of ILT and AAA sac ratios were 0.59 ± 0.17 and 0.52 ± 1.8 in growing AAA sac and in stable or shrinking AAA sac groups, respectively (p = 0.308).ConclusionsVolumetric AAA measurement may be useful as an additional method to diameter measurement after EVAR to identify clinically relevant sac growth. Preoperative volume of ILT may not significantly affect the growth rate of AAA after EVAR.

Invited commentary

Abdominal aortic aneurysm (AAA) accounts for >20 million deaths worldwide.1Golledge J. Norman P.E. Murphy M.P. Dalman R.L. Challenges and opportunities in limiting abdominal aortic aneurysm growth.J Vasc Surg. 2017; 65: 225-233Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar Extrapolating from the National Inpatient Sample data set capturing 20% of inpatients in the United States, approximately 500,000 operations for AAA were performed from 2000 to 2010.2Dua A. Ali F. Traudt E. Desai S.S. Utilization of the National Inpatient Sample for abdominal aortic aneurysm research.Surgery. 2017; 162: 699-706Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar The number of aneurysms fixed by endovascular aneurysm repair increased from 5% to approximately 75% during that period, with concomitant improvements in mortality and morbidity within 2 to 3 years of surgery.2Dua A. Ali F. Traudt E. Desai S.S. Utilization of the National Inpatient Sample for abdominal aortic aneurysm research.Surgery. 2017; 162: 699-706Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar, 3Weinkauf C. George E. Zhou W. Open versus endovascular aneurysm repair trial review.Surgery. 2017; 162: 974-978Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar Similar to the advancements offered by endovascular aneurysm repair, medical treatments that could reduce the growth rate of AAA even modestly would save lives and radically alter clinical practice. Perhaps research in this area truly represents an opportunity to “work ourselves out of a job” toward the benefit of patients' well-being. Thus, we continue to strive for a medical treatment that reduces AAA growth rate in the face of disappointing results associated with promising agents like doxycycline.4Meijer C. Stijnen T. Wasser M.M. Hamming J.F. van Bockel J.H. Lindeman J.H. Pharmaceutical Aneurysm Stabilisation Trial Study GroupDoxycycline for stabilization of abdominal aortic aneurysms: a randomized trial.Ann Intern Med. 2013; 159: 815-823Crossref PubMed Scopus (146) Google Scholar The report by Tsai et al evaluates benefits of fucoidan, an extract from brown seaweed, in reducing experimentally induced AAA in mice. The authors report a premise to study fucoidan in cardiovascular disease because of its anti-inflammatory, anticoagulant, and antihypertensive effects. The investigators demonstrate that in a murine model of AAA induced by infusing angiotensin II through a subcutaneous pump, aortic diameter was reduced by intraperitoneal administration of fucoidan. Treatment also mitigated degradation of aortic elastin, diminished inflammatory cell recruitment, and reduced the activities of matrix metalloproteinases (MMPs) thought to degrade extracellular matrix. In human umbilical vein endothelial cells, fucoidan also reduced MMP activity as well as reactive oxygen species expression. The authors conclude that whereas more research needs to be done, fucoidan may be a promising supplement for patients with small aneurysms. There are a few questions that emerge from the report that are worth investigating. It is not clear from the study what role inflammatory cells play in the protective process. Does the fucoidan limit elastin degradation because of a direct effect on elastin or because of an effect on inflammatory cells? Is it relevant to evaluate MMP activity and reactive oxygen species in human umbilical vein endothelial cells when the model is a murine model of aortic disease? Do angiotensin II infusion models of AAA adequately reflect the human condition that typically takes years to develop and is multifactorial? Finally, how would fucoidan be given to a patient? Could it be an oral supplement, or would it need to be administered parenterally, and if so, how often? The authors have alluded to these limitations and have committed to pursuing some of the answers in future studies. While research into aneurysm growth retardants continues, we can only offer surveillance until the aortic diameter thresholds warrant repair. The opinions or views expressed in this commentary are those of the authors and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. Fucoidan attenuates angiotensin II-induced abdominal aortic aneurysms through the inhibition of c-Jun N-terminal kinase and nuclear factor κB activationJournal of Vascular SurgeryVol. 68Issue 6PreviewRupture of abdominal aortic aneurysm (AAA) is one of the leading causes of sudden death among the elderly. Most incidental AAAs are below the threshold for intervention at the time of detection; however, there is no evidence that commonly used cardiovascular drugs have clinical beneficial effects on AAA progression. Therefore, in addition to current cardiovascular risk-reducing treatments, an adjunctive medical therapy targeting the regulation of extracellular matrix metabolism is still required in the clinical setting. Full-Text PDF Open Archive

Effect of intraluminal thrombus on growth rate of abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) includes a variety of morphologies with changing properties. Growth rate is one of the most important factors directly linked to the risk of rupture. Intraluminal thrombus (ILT) covering aortic wall is found in the majority of AAAs. Yet, its role in biomechanical processes in AAA remains unclear. From one point of view ILT can serve as protective factor in reducing wall stress of AAA and thus slow down the growth. Modern concept of multilayered ILT proved active inflammatory processes inside, that can significantly affect the quality of the wall and thus lead to a higher growth rate and higher risk of rupture. The goal of this study was to analyze the effect of ILT on growth rate of AAA and support one of these theories. Retrospective study of computed tomography angiography scans of AAA of 26 patients was performed. Forty pairs of consecutive scans have been analyzed. Periods between two scans varied. Maximal infrarenal diameter of AAA and size of ILT were measured. AAAs were split into 4 groups according to their initial diameter. Growth rate was calculated for each AAA and linked to the relative size of ILT. These values were statistically evaluated. Negative correlation between relative size of ILT and growth rate was found (P=0.042062). This significant result proved that thicker thrombus slowed down the growth of AAA and vice versa, smaller relative size of ILT was linked to higher growth rate. This finding shows importance of ILT as one of the key factors influencing biomechanical processes inside an AAA. Results of this study may contribute to future researches of this topic.

Plasma Cystatin B Association With Abdominal Aortic Aneurysms and Need for Later Surgical Repair: A Sub-study of the VIVA Trial

The development of an abdominal aortic aneurysm (AAA) involves extensive extracellular matrix remodelling, leading to aortic wall weakening. This process is mediated by proteases, including cysteinyl cathepsins. Cystatins are their endogenous inhibitors. This study tested whether plasma cystatin B levels in patients with AAA differed from those of healthy controls. Plasma samples from patients with AAA and age matched controls were selected from the Viborg Vascular (VIVA) screening trial for AAA. Enzyme linked immunosorbent assay determined plasma cystatin B. T-test, logistic regression, Pearson's correlation and Cox regression tested whether plasma cystatin B correlates with AAA size and growth rate, or serves as a marker for AAA. Plasma cystatin B levels were significantly higher in patients with AAA than in controls (p<0.001). Logistic regression analysis showed that cystatin B tertile at baseline was associated with the presence of AAA before (odds ratio [OR] 1.656; p<0.001) and after adjustment for peripheral arterial disease (PAD), chronic obstructive pulmonary disease (COPD), and previous ischaemic events (OR 1.526; p<0.001). A t-test showed a significant association between cystatin B and PAD at screening, hospital diagnosis of COPD, previous atherosclerotic events, and use of low dose aspirin. Pearson's correlation test showed positive and significant associations between cystatin B and AAA size (r= 0.15; p<0.001). Cox regression test showed that plasma cystatin B tertile at baseline was associated with later AAA surgical repair before (hazard ratio [HR] 1.387; p<0.001) and after adjustment for PAD, COPD, previous ischaemic event, and maximum infrarenal aortic diameter (HR 1.523; p<0.001). In contrast to prior studies that showed that cystatin C is negatively associated with AAA development, this study demonstrated a positive association between cystatin B and AAA size and associations between cystatin B tertile at baseline and AAA presence and need for later surgical repair. It is possible that these two cystatins inhibit cathepsin activity and participate in AAA with different mechanisms.

Metformin prescription status and abdominal aortic aneurysm disease progression in the U.S. veteran population

BackgroundIdentification of a safe and effective medical therapy for abdominal aortic aneurysm (AAA) disease remains a significant unmet medical need. Recent small cohort studies indicate that metformin, the world's most commonly prescribed oral hypoglycemic agent, may limit AAA enlargement. We sought to validate these preliminary observations in a larger cohort. MethodsAll patients with asymptomatic AAA disease managed in the Veterans Affairs Health Care System between 2003 and 2013 were identified by International Classification of Diseases, Ninth Revision codes. Those with a concomitant diagnosis of diabetes mellitus who also received two or more abdominal imaging studies (computed tomography, magnetic resonance imaging, or ultrasound) documenting the presence and size of an AAA, separated by at least 1 year, were included for review. Maximal AAA diameters were determined from radiologic reports. Further data acquisition was censored after surgical AAA repair, when performed. Comorbidities, active smoking status, and outpatient medication records (within 6 months of AAA diagnosis) were also queried. Yearly AAA enlargement rates, as a function of metformin treatment status, were compared using two statistical models expressed in millimeters per year: a multivariate linear regression (model 1) and a multivariate mixed-effects model with random intercept and random slope (model 2). ResultsA total of 13,834 patients with 58,833 radiographic records were included in the analysis, with radiology imaging follow-up of 4.2 ± 2.6 years (mean ± standard deviation). The average age of the patients at AAA diagnosis was 69.8 ± 7.8 years, and 39.7% had a metformin prescription within ±6 months of AAA. The mean growth rate for AAAs in the entire cohort was 1.4 ± 2.0 mm/y by model 1 analysis and 1.3 ± 1.6 mm/y by model 2 analysis. The unadjusted mean rate of AAA growth was 1.2 ± 1.9 mm/y for patients prescribed metformin compared with 1.5 ± 2.2 mm/y for those without (P < .001), a 20% decrease. This effect remained significant when adjusted for variables relevant on AAA progression: metformin prescription was associated with a reduction in yearly AAA growth rate of −0.23 mm (95% confidence interval, −0.35 to −0.16; P < .001) by model 1 analysis and 0.20 mm/y (95% confidence interval, −0.26 to −0.14; P < .001) by model 2 analysis. A subset analysis of 7462 patients with baseline AAA size of 35 to 49 mm showed a similar inhibitory effect (1.4 ± 2.0 mm/y to 1.7 ± 2.2 mm/y; P < .001). Patients' factors associated with an increased yearly AAA growth rate were baseline AAA size, metastatic solid tumors, active smoking, chronic obstructive pulmonary disease, and chronic renal disease. Factors associated with decreased yearly AAA growth rates included prescriptions for angiotensin II type 1 receptor blockers or sulfonylureas and the presence of diabetes-related complications. ConclusionsIn a nationwide analysis of diabetic Veterans Affairs patients, prescription for metformin was associated with decreased AAA enlargement. These findings provide further support for the conduct of prospective clinical trials to test the ability of metformin to limit progression of early AAA disease.

The Relationship Between Serum Interleukin-1α and Asymptomatic Infrarenal Abdominal Aortic Aneurysm Size, Morphology, and Growth Rates

In a pilot study, a relationship between abdominal aortic aneurysm (AAA) diameter and serum interleukin (IL)-1α levels was reported, and that endothelial cell (EC) activation invitro in response to serum from patients with AAA was blocked by anti-IL-1α antibodies. The aim of the present study was to further investigate the relationship between serum IL-1α and asymptomatic infrarenal AAA size, morphology, and growth rates. Serum IL-1α was measured using enzyme linked immunosorbent assay in 101 patients with asymptomatic, infrarenal AAA and related to aneurysm size, morphology, and growth rates. IL-1α was measured in 101 patients. There was no statistically significant difference in mean age between men and women. IL-1α was detectable in 62.4% of patients; median IL-1α titre was 3.26pg/mL. There was no statistically significant relationship between IL-1α and maximum AAA antero-posterior diameter as measured by ultrasound (p=.649), AAA morphology (aortic length [p=.394], sac [p=.369], and thrombus volume [p=.629]) as measured on computed tomography, absolute increase in AAA diameter (p=.214), or AAA growth rate (p=.230). IL-1α is detectable in the majority of patients with infrarenal AAA, but the cause and clinical significance of this novel observation remains unknown.

Meta-Analysis of the Association Between Peripheral Artery Disease and Growth of Abdominal Aortic Aneurysms

Background: The role of atherosclerosis in the pathogenesis of abdominal aortic aneurysm (AAA) is controversial. Atherosclerosis-associated peripheral artery disease (PAD) has been reported to be a risk factor for AAA in population screening studies; its relationship with AAA growth is controversial. Methods: A systematic search of MEDLINE, Scopus, CINAHL and the Cochrane Central Register of Controlled Trials was conducted in April 2016 and repeated in January 2017. Databases were screened for studies reporting AAA growth rates in patients with, and without PAD. The included studies underwent quality assessment and, where possible, were included in the meta-analysis. A subgroup analysis was performed, including only studies that adjusted for confounding factors. Results: Seventeen studies, including a total of 4873 patients, met the review entry criteria. Data from 15 studies were included in the meta-analysis. There was marked heterogeneity in study design, methodology and statistical analyses used. In the main analysis, PAD was associated with reduced AAA growth (mean difference – 0·13, 95 per cent c.i. –0·27 to –0·00; P = 0·04). However, statistical significance was not maintained in sensitivity analysis. In a subanalysis that included only data adjusted for other risk factors, no significant association between PAD and AAA growth was found (mean difference –0·11, –0·23 to 0·00; P = 0·05). Conclusion: This systematic review suggests that currently reported studies demonstrate no robust and consistent association between PAD and reduced AAA growth.

Common First-Pass CT Angiography Findings Associated With Rapid Growth Rate in Abdominal Aorta Aneurysms Between 3 and 5 cm in Largest Diameter.

The purpose of this study was to describe CT angiography (CTA) findings of lumen contrast heterogeneity and intraluminal thrombus volume and to evaluate their relationship with rapid aneurysm growth in patients with abdominal aortic aneurysms (AAA) between 3 and 5 cm. This institutional review board-approved and HIPAA-compliant single-center retrospective study included CTA studies obtained between January 2004 and December 2014 in 140 patients with AAA (101 men, 39 women; mean age ± SD, 70 ± 9 years old; age range, 22-87 years old). Standardized measurements for aneurysm intraluminal thrombus volume and a relatively new metric termed "lumen contrast heterogeneity" were obtained from the CTA images. AAA growth rate data were acquired from all subsequent cross-sectional studies. The association between the imaging findings and rapid aneurysm growth (> 0.4 cm/y) was evaluated using multivariate logistic regression. Patient comorbidities and medications were added to the regression model to assess for further associations with rapid growth rate. Using a baseline logistic regression model, lumen contrast heterogeneity (odds ratio [OR], 1.16; 95% CI, 1.05-1.32), intraluminal thrombus volume (OR, 2.15; 95% CI, 1.26-3.86), and maximum AAA diameter (OR, 1.69; 95% CI, 1.03-2.84) were independently associated with increased likelihood of rapid aneurysm growth. None of the patient comorbidities or medications were significantly associated with the outcome when added to the baseline model. Both intraluminal thrombus and lumen contrast heterogeneity are seen on AAA CTA studies and can be quantified; both of these metrics are independently associated with rapid growth rate and should be recognized by radiologists evaluating patients with AAA during surveillance.

Lessons learned about prevalence and growth rates of abdominal aortic aneurysms from a 25-year ultrasound population screening programme.

This study aimed to assess how the prevalence and growth rates of small and medium abdominal aortic aneurysms (AAAs) (3·0-5·4 cm) have changed over time in men aged 65 years, and to evaluate long-term outcomes in men whose aortic diameter is 2·6-2·9 cm (subaneurysmal), and below the standard threshold for most surveillance programmes. The Gloucestershire Aneurysm Screening Programme (GASP) started in 1990. Men aged 65 years with an aortic diameter of 2·6-5·4 cm, measured by ultrasonography using the inner to inner wall method, were included in surveillance. Aortic diameter growth rates were estimated separately for men who initially had a subaneurysmal aorta, and those who had a small or medium AAA, using mixed-effects models. Since 1990, 81 150 men had ultrasound screening for AAA (uptake 80·7 percent), of whom 2795 had an aortic diameter of 2·6-5·4 cm. The prevalence of screen-detected AAA of 3·0 cm or larger decreased from 5·0 percent in 1991 to 1·3 percent in 2015. There was no evidence of a change in AAA growth rates during this time. Of men who initially had a subaneurysmal aorta, 57·6 (95 percent c.i. 54·4 to 60·7) percent were estimated to develop an AAA of 3·0 cm or larger within 5 years of the initial scan, and 28·0 (24·2 to 31·8) percent to develop a large AAA (at least 5·5 cm) within 15 years. The prevalence of screen-detected small and medium AAAs has decreased over the past 25 years, but growth rates have remained similar. Men with a subaneurysmal aorta at age 65 years have a substantial risk of developing a large AAA by the age of 80 years.

Temporal Changes in Intraluminal Thrombus Volume Within Abdominal Aortic Aneurysms: Implications for Planning Endovascular Aneurysm Sealing

Purpose: To explore whether or not there are temporal changes in the abdominal aortic aneurysm (AAA) and intraluminal thrombus (ILT) volumes between planning and implantation of the endovascular aneurysm sealing (EVAS) device and how these changes influence lumen volume. Methods: A retrospective review was conducted of 51 AAA patients (mean age 76±7.1 years; 36 men) in whom 2 serial preoperative computed tomography angiograms (CTAs) had been performed within 1 to 18 months before fenestrated endovascular repair. The 2 preoperative CTAs were analyzed to identify changes in total sac, ILT, and lumen volumes. Results: Over a median 7.0 months (interquartile range 4, 10), 46 (90%) of 51 AAAs increased in volume between the 2 CTAs. ILT volume increased in 44 aneurysms. In contrast, lumen volume increased in 31 and decreased in 20 AAAs. There was a strong correlation between changes in AAA volume and ILT volume (rs=0.859, p<0.001), which remained significant after adjustment for initial volumes (rs=0.815; p<0.001). There was no correlation between the time interval separating the 2 CTAs and changes in AAA volume (rs=0.115; p=0.421), changes in ILT volume (rs=0.084; p=0.599), or changes in lumen volume (rs=0.060; p=0.676). The AAA growth rate (defined as the change in AAA size/days between CTAs) showed a weak correlation with ILT volume (rs=0.272, p=0.054), which disappeared after adjustment for initial AAA size (rs=−0.002, p=0.991). Between the 2 CTAs, 12 aneurysms crossed the new <1.4 Nellix maximum aorta/lumen diameter ratio. Conclusion: As AAAs grow, the increase in aortic volume is largely occupied by additional ILT formation, with minimal change in lumen volume. These changes may alter the suitability of the aneurysm for the Nellix device and could have implications for EVAS planning and device deployment.

Meta-analysis of the association between peripheral artery disease and growth of abdominal aortic aneurysms.

The role of atherosclerosis in the pathogenesis of abdominal aortic aneurysm (AAA) is controversial. Atherosclerosis-associated peripheral artery disease (PAD) has been reported to be a risk factor for AAA in population screening studies; its relationship with AAA growth is controversial. A systematic search of MEDLINE, Scopus, CINAHL and the Cochrane Central Register of Controlled Trials was conducted in April 2016 and repeated in January 2017. Databases were screened for studies reporting AAA growth rates in patients with, and without PAD. The included studies underwent quality assessment and, where possible, were included in the meta-analysis. A subgroup analysis was performed, including only studies that adjusted for confounding factors. Seventeen studies, including a total of 4873 patients, met the review entry criteria. Data from 15 studies were included in the meta-analysis. There was marked heterogeneity in study design, methodology and statistical analyses used. In the main analysis, PAD was associated with reduced AAA growth (mean difference-0·13, 95 per cent c.i. -0·27 to -0·00; P = 0·04). However, statistical significance was not maintained in sensitivity analysis. In a subanalysis that included only data adjusted for other risk factors, no significant association between PAD and AAA growth was found (mean difference -0·11, -0·23 to 0·00; P = 0·05). This systematic review suggests that currently reported studies demonstrate no robust and consistent association between PAD and reduced AAA growth.

International opinion on priorities in research for small abdominal aortic aneurysms and the potential path for research to impact clinical management

Landmark trials of surgery for small abdominal aortic aneurysms (AAA), which included patients with AAA sizes between 40-55mm, did not demonstrate medium term survival benefits of early surgery in these patients[1]. However, these trials also showed the variation in AAA growth rates between individuals, and that the majority of patients with small AAAs would eventually progress to the threshold of 55mm within 5 years. There is no existing literature to highlight priorities for research in the subject of AAA. To address this, we conducted an online survey to vascular surgery colleagues internationally to obtain a global opinion on the priorities for research for AAA.

Magnetic resonance imaging of the intraluminal thrombus in abdominal aortic aneurysms: a quantitative and qualitative evaluation and correlation with growth rate.

The role of the intraluminal thrombus (ILT) in abdominal aortic aneurysm (AAA) growth remains incompletely understood. MRI is superior to other methods in depicting the morphology of the ILT. This study brings preliminary, but novel information on the presence and morphological characteristics of the ILT and AAA growth rates in a screening cohort. Cohort study with 46 patients from the Viborg Vascular Trial. All underwent one non-contrast-enhanced magnetic resonance imaging (MRI) at the end of follow-up. ILT presence was noted and, if present, it was allocated to one of four morphological categories based on visual appearance and signal intensity on T2 weighted images. The mean growth rate was 1.95 mm/year ±0.87 (SD). The observation time was 5.59±0.63 (SD) years. ILT was present in AAA size groups as follows: 30-34.9 mm 20.00%, 35-39.9 mm 88.89%, 40-44.9 mm 81.25%, 45-49.9 mm 100% and 50-54.9 mm 100%. Out of 46, 8 had no ILT at the time of MRI. The presence of any sort of ILT yielded a significantly increased unadjusted and an adjusted growth rate of 1.09 mm/year (95% CI: 0.48; 1.70) and 1.24 mm/year (95% CI: 0.64; 1.83), respectively. All four thrombus types were retrospectively associated with an increased recorded growth rate compared with "no thrombus". Presence of a thin circumferential thrombus was retrospectively associated with the highest increase in growth rate, viz. 2.09 mm/year (95% CI: 1.23; 2.95). We observed faster growth rate in those AAA that had developed an ILT. Even faster growth was observed amongst those AAA containing a thin ILT located along the inner circumference.