AAA Growth Research Articles

Change in Smoking Habits After Having Been Screened for Abdominal Aortic Aneurysm

To study smoking habits among men with abdominal aortic aneurysm at screening at 65 years of age, and during follow-up, as a base-line study to evaluate future interventions. Nested case-control study. Between 2006 and 2011, 8150 65-year-old men (compliance 85%) were screened for AAA in Uppsala County, Sweden. Among 292 men with an aortic diameter of at least 25 mm, 77 were active smokers at the time of screening. At follow-up of smoking habits in 2012, 53 men (69%) participated in this study, 28 had an AAA of at least 30 mm and 25 a sub-aneurysmal aorta (SAA) 25-29 mm at baseline. For each case, one control was randomly selected, all active smokers with aortic diameter less than 25 mm at baseline, matched for age and year of screening. Telephone interviews were performed at a median 34 months (range: 4-67) after screening. Men with AAA had hypertension more often than controls (68% vs. 23%, p < .001). Men with AAA and SAA reported more smoking years than controls (p = .017). Cessation rate among patients with AAA did not differ significantly compared with men with an aorta less than 30 mm (29% vs. 15%, p = .159), but they had reduced their consumption of cigarettes/day significantly more than men with SAA and controls (-8.2 vs. -3.0 vs. -4.5, p = .030). Men with AAA recalled having been informed about the importance of smoking cessation at the time of screening more often (p = .031). There was no difference in growth of the AAA between those who continued, and those who quit smoking (2.03 vs. 2.01 mm/year, p = .982), but the study was not powered to study AAA growth. Although counselling in a normal healthcare setting had some effect, the results indicate a need to tailor interventions to further increase smoking cessation rates among men diagnosed with both AAA and SAA.

PW01-006 – The effect of colchicine on physical growth in FMF

Familial Mediterranean fever is the most periodic fever sendrome and characterized by reccurent fever, abdominal pain, chest pain, arthritis/ arthralgia and erizipel like rash and self limited attacks with fever and serozal inflomation also elevated acute phase reactants. As with other chronic inflammatory diseases in patients with AAA growth may be negative effects.

Systematic review and meta-analysis of the growth and rupture rates of small abdominal aortic aneurysms: implications for surveillance intervals and their cost-effectiveness

Small abdominal aortic aneurysms (AAAs; 3.0-5.4 cm in diameter) are usually asymptomatic and managed by regular ultrasound surveillance until they grow to a diameter threshold (commonly 5.5 cm) at which surgical intervention is considered. The choice of appropriate surveillance intervals is governed by the growth and rupture rates of small AAAs, as well as their relative cost-effectiveness. The aim of this series of studies was to inform the evidence base for small AAA surveillance strategies. This was achieved by literature review, collation and analysis of individual patient data, a focus group and health economic modelling. We undertook systematic literature reviews of growth rates and rupture rates of small AAAs. The databases MEDLINE, EMBASE on OvidSP, Cochrane Central Register of Controlled Trials 2009 Issue 4, ClinicalTrials.gov, and controlled-trials.com were searched from inception up until the end of 2009. We also obtained individual data on 15,475 patients from 18 surveillance studies. Systematic reviews of publications identified 15 studies providing small AAA growth rates, and 14 studies with small AAA rupture rates, up to December 2009 (later updated to September 2012). We developed statistical methods to analyse individual surveillance data, including the effects of patient characteristics, to inform the choice of surveillance intervals and provide inputs for health economic modelling. We updated an existing health economic model of AAA screening to address the cost-effectiveness of different surveillance intervals. In the literature reviews, the mean growth rate was 2.3 mm/year and the reported rupture rates varied between 0 and 1.6 ruptures per 100 person-years. Growth rates increased markedly with aneurysm diameter, but insufficient detail was available to guide surveillance intervals. Based on individual surveillance data, for each 0.5-cm increase in AAA diameter, growth rates increased by about 0.5 mm/year and rupture rates doubled. To control the risk of exceeding 5.5 cm to below 10% in men, on average a 7-year surveillance interval is sufficient for a 3.0-cm aneurysm, whereas an 8-month interval is necessary for a 5.0-cm aneurysm. To control the risk of rupture to below 1%, the corresponding estimated surveillance intervals are 9 years and 17 months. Average growth rates were higher in smokers (by 0.35 mm/year) and lower in patients with diabetes (by 0.51 mm/year). Rupture rates were almost fourfold higher in women than men, doubled in current smokers and increased with higher blood pressure. Increasing the surveillance interval from 1 to 2 years for the smallest aneurysms (3.0-4.4 cm) decreased costs and led to a positive net benefit. For the larger aneurysms (4.5-5.4 cm), increasing surveillance intervals from 3 to 6 months led to equivalent cost-effectiveness. There were no clear reasons why the growth rates varied substantially between studies. Uniform diagnostic criteria for rupture were not available. The long-term cost-effectiveness results may be susceptible to the modelling assumptions made. Surveillance intervals of several years are clinically acceptable for men with AAAs in the range 3.0-4.0 cm. Intervals of around 1 year are suitable for 4.0-4.9-cm AAAs, whereas intervals of 6 months would be acceptable for 5.0-5.4-cm AAAs. These intervals are longer than those currently employed in the UK AAA screening programmes. Lengthening surveillance intervals for the smallest aneurysms was also shown to be cost-effective. Future work should focus on optimising surveillance intervals for women, studying whether or not the threshold for surgery should depend on patient characteristics, evaluating the usefulness of surveillance for those with aortic diameters of 2.5-2.9 cm, and developing interventions that may reduce the growth or rupture rates of small AAAs. The National Institute for Health Research Health Technology Assessment programme.

Is Oxidative Stress Important in AAA Pathogenesis?

Active investigations continue to identify markers other than size that would predict a risk of AAA rupture. Circulating biomarkers could also indicate optimal intervals between the surveillance intervals. Finally, the identification of biomarkers also may identify potential pathogenic pathways, and thus may open possibilities for pharmacological inhibition of growth. In the search of novel biomarkers of AAA progression, serum and wall material proteins were analyzed by a differential proteomic approach. Same layers of AAA wall from ruptured (rAAA) and non-ruptured AAA were incubated, and the proteins released were analyzed by 2-dimensional difference in-gel electrophoresis. Proteins from serum were analyzed and correlated with AAA annual expansion rate. Several differentially expressed proteins involved in main AAA pathological mechanisms (proteolysis, oxidative stress, and thrombosis) were identified by mass spectrometry. Among the proteins identified, peroxiredoxin-2 (PRX-2) was more permanent, which was further validated by Western blot and immunohistochemistry. We demonstrated increased PRX-2 serum levels in rAAA patient wall material compared with AAA subjects and also positive correlation in serum among PRX-2 and AAA diameter and annual expansion rate. Finally, a prospective study revealed a positive correlation between PRX-2 serum levels and AAA expansion rate. Several proteins associated with AAA pathogenesis have been identified by a proteomic approach Protein profiles identified in the serum would appear to be a convenient monitoring tool that has the ability to be both sensitive and specific for AAAs. PRX-2 serum levels are increased in rAAA patients and correlate with AAA size and growth rate, suggesting the potential use of PRX-2 as a biomarker for AAA evolution.

Surveillance Intervals for Small Abdominal Aortic Aneurysms

Small abdominal aortic aneurysms (AAAs [3.0 cm-5.4 cm in diameter]) are monitored by ultrasound surveillance. The intervals between surveillance scans should be chosen to detect an expanding aneurysm prior to rupture. To limit risk of aneurysm rupture or excessive growth by optimizing ultrasound surveillance intervals. Individual patient data from studies of small AAA growth and rupture were assessed. Studies were identified for inclusion through a systematic literature search through December 2010. Study authors were contacted, which yielded 18 data sets providing repeated ultrasound measurements of AAA diameter over time in 15,471 patients. AAA diameters were analyzed using a random-effects model that allowed for between-patient variability in size and growth rate. Rupture rates were analyzed by proportional hazards regression using the modeled AAA diameter as a time-varying covariate. Predictions of the risks of exceeding 5.5-cm diameter and of rupture within given time intervals were estimated and pooled across studies by random effects meta-analysis. AAA growth and rupture rates varied considerably across studies. For each 0.5-cm increase in AAA diameter, growth rates increased on average by 0.59 mm per year (95% CI, 0.51-0.66) and rupture rates increased by a factor of 1.91 (95% CI, 1.61-2.25). For example, to control the AAA growth risk in men of exceeding 5.5 cm to below 10%, on average, a 7.4-year surveillance interval (95% CI, 6.7-8.1) is sufficient for a 3.0-cm AAA, while an 8-month interval (95% CI, 7-10) is necessary for a 5.0-cm AAA. To control the risk of rupture in men to below 1%, the corresponding estimated surveillance intervals are 8.5 years (95% CI, 7.0-10.5) and 17 months (95% CI, 14-22). In contrast to the commonly adopted surveillance intervals in current AAA screening programs, surveillance intervals of several years may be clinically acceptable for the majority of patients with small AAA.

RR4. Sideways Movement of the Endograft Within the Aneurysm Sac Is Associated With Late Adverse Events

Previous studies have shown the importance of proximal and distal endograft fixation. There is little information on the middle, unsupported section of the endograft. We have quantified sideways movement of the endograft within the AAA sac and correlated it to late adverse events. Patients who underwent EVAR between January 1997 and December 2007 were analyzed. Patients with a digital available preoperative CT-angiography (CTA), postoperative CTA and at least one follow-up CTA thereafter were included. Changes in endograft position within the AAA sac were measured. Patients with sideways movement ≥5mm were placed in the movement group (MG) and were compared with patients with no movement (<5mm, NM group). To analyze the association of sideways endograft movement and EVAR related complication the following outcome measures were noted: AAA rupture, AAA-related death, conversion, secondary procedures, AAA growth (≥5mm), proximal migration (≥10mm), and new onset type 1/3 endoleaks. 144 patients (mean age 76 year) were included. Follow-up was 43 ± 27 months. Fifty patients (35%) had sideways endograft movement. AAA diameter (MG 60 ± 9 vs NM 57 ± 9mm, p < 0.05), and proximal and iliac endograft fixation lengths were significantly different between the groups (MG 18 ± 8 vs NM 25 ± 11mm, p < 0.05 and MG 35 ± 15 vs NM 42 ± 16mm, p < 0.05). There was no significant difference between the groups in terms of AAA rupture and AAA-related death (one fatal AAA rupture, NM group). Patients in the MG group had a significantly higher conversion rate (14 vs 0%, p < 0.001) and had more secondary procedures (44 vs 6%, p < 0.001). Patients in the MG had significantly more AAA growth (42 vs 10%, p < 0.001), more proximal migration (66 vs 5%, p < 0.001) and more often type 1/3 endoleaks (36 vs 3%, p < 0.001). Sideways movement of the device within the AAA sac is associated with late adverse events. Conversely, lack of movement is correlated with long-term success.

Optimizing compliance, efficiency, and safety during surveillance of small abdominal aortic aneurysms

Outcome data documenting safety for observation of small abdominal aortic aneurysms (AAA 4.0 to 5.4 cm) are lacking outside of large clinical trials but requires near perfect patient compliance. This study describes a clinical pathway for AAA surveillance using a prospective database utilizing a nurse practitioner oversight to provide efficient use of clinic visits while maintaining a high level of patent participation. Over a 7-year period (June 1999 through June 2006), 334 patients were enrolled in an AAA surveillance pathway at our academic veterans hospital. To minimize patient travel, clinic visitation was reserved for an initial examination with patient education and for discussion of intervention options in patients demonstrating AAA growth (>5.4 cm or expansion >1 cm/yr) during follow-up. Biannual ultrasound or CT imaging was scheduled and results discussed (after physician review) via telephone or "same day" direct patient contact. An electronic database was used to update patient information and plan follow-up. Compliance with the AAA surveillance pathway was achieved in 98.5% of patients, with only three patients (0.9%) lost to follow-up and two others (0.6%) choosing early repair at civilian institutions. At a mean interval of 29 months (+/-20 mo), surgical repair was performed in 225 (67%) patients by open (n = 143) or endovascular (n = 82) techniques for AAA growth to >5.4 cm (n = 219) or expansion by >1cm/yr (n = 6). One hundred six patients currently remain in surveillance. A single AAA rupture resulting in death occurred during surveillance (0.3%) and perioperative mortality (<60 days) was 0.9% in patients needing intervention for AAA growth. Cumulative aneurysm-related mortality was 0.9% for patients compliant with the AAA surveillance pathway. Use of a prospectively-maintained surveillance database managed by a non-physician provider with a reliance on telephone contact resulted in a high degree of patient compliance, reduced unnecessary patient travel, and provided practical clinic use. Limited additional resources were needed to implement our pathway and a similar approach may prove useful for large volume hospital, clinic, or practice systems.

Surveillance of small aortic aneurysms does not alter anatomic suitability for endovascular repair

Small abdominal aortic aneurysms (AAAs; 4-5.4 cm) are more likely to be suitable for endovascular aneurysm repair (EVAR) than large aortic aneurysms (>5.5 cm). The purpose of this study was to determine whether small AAA growth is associated with the development of morphologic characteristics that decrease eligibility for EVAR. We studied 54 patients who underwent 2 or more computed tomography scans with 3-dimensional reconstruction during surveillance of small AAAs. Morphologic aortic aneurysm features and changes were measured according to Society for Vascular Surgery reporting standards. Suitability for EVAR was determined by neck anatomy (diameter, length, and angulations), iliac artery morphology, and total aortic aneurysm angulation and tortuosity. The median age of the study cohort was 73 years (interquartile range [IQR], 65-77 years). The median follow-up period was 24 months (IQR, 15-36 months). The median small AAA diameter increased from 44.5 mm (IQR, 41-48 mm) to 48.9 mm (IQR, 45.7-52.0 mm). The median aortic neck diameter increased from 23.0 to 24.0 mm (P = .002), whereas median neck length decreased from 26.5 to 20.0 mm (P = .001). Aortic aneurysm median tortuosity index increased from 1.09 to 1.11 (P = .05). No significant changes in iliac artery morphology occurred. Overall, the anatomic suitability for endovascular repair did not significantly change during the study period (74% vs 69%; McNemar test; P = .25). Changes in aortic morphology are frequently associated with small AAA growth at mid-term follow-up, but such changes are minor and do not affect overall anatomic suitability for EVAR. These data reveal that continued surveillance of small AAAs does not threaten the window of opportunity for EVAR.

Hyperhomocysteinaemia is Associated with the Rate of Abdominal Aortic Aneurysm Expansion

Previous literature has suggested an association between AAA and the presence of elevated plasma homocysteine levels (HCY). Homocysteine can stimulate elastolysis in the arterial media via activation of elastase and matrix metalloproteinases. No evidence in the literature exists correlating aneurysm expansion and HCY. The study objective is to identify whether the rate of AAA expansion is related to HCY. 108 patients undergoing surveillance for AAA were identified at our vascular surgical unit. AAA size and growth rate were assessed by serial ultrasonographic measurements. Fasting total HCY levels were measured using fluorescence polarisation immunoassays. Demographic details and atherosclerotic risk factors were noted all AAA patients. A multivariate analysis was performed for growth rate vs. HCY, hypertension and hypercholesterolaemia. The correlation between AAA growth rate, AAA size and HCY levels were calculated. 60% of patients with AAA had some degree of hyperhomocysteinaemia (> 15 micromol/l). Multivariate analysis showed HCY to be the only significant factor affecting AAA growth rate. A positive correlation was demonstrated between HCY levels and AAA growth rate using a linear regression model (R=0.28, p=0.003). Median growth rate among patients with hyperHCY was double that of patients with normal HCY (0.5 mm/month vs. 0.25 mm/month, p=0.003). A growth rate of > 10 mm/year was seen in 25% of hyper HCY patients and in only 2% of patients with normal HCY. In addition patients with hyper HCY and larger AAAs (> 4 cm) had a growth rate twice as fast as patients with hyper HCY and AAAs < 4 cm. A correlation between HCY and growth rate exists, although this is weak due to the multifactorial aetiology of AAAs. HyperHCY patients have faster expansion rates than patients with normal HCY, with significant numbers demonstrating rapid expansion (> 10 mm/year) and therefore an increased risk of rupture.

Statins are Associated with a Reduced Infrarenal Abdominal Aortic Aneurysm Growth

Objective To evaluate the effect of statins on aneurysm growth in a group of consecutive patients under surveillance for infrarenal aortic aneurysms (AAA). Materials and methods All patients (59 statin users, 91 non-users) under surveillance between January 2002 and August 2005 with a follow-up for aneurysm growth of at least 12 months and a minimum of three diameter evaluations were retrospectively included in the analysis. Multiple regression analysis, weighted with the number of observations, was performed to test the influence of statins on AAA growth rate. Results During a median period of 3.1 (1.1–13.1) years the overall mean aneurysm growth rate was 2.95±2.8 mm/year. Statin users had a 1.16 mm/year lower AAA growth rate compared to non-users (95% CI 0.33–1.99 mm/year). Increased age was associated with a slower growth (−0.09 mm/year per year, p=0.003). Female gender (+1.82 mm/year, p=0.008) and aneurysm diameter (+0.06 mm/year per mm, p=0.049) were associated with increased AAA growth. The use of non-steroidal anti-inflammatory drugs, chronic lung disease, or other cardiovascular risk factors were not independently associated with AAA growth. Conclusions Statins appear to be associated with attenuation of AAA growth, irrespective of other known factors influencing aneurysm growth.

Clinical failures of endovascular abdominal aortic aneurysm repair: incidence, causes, and management.

Despite well-documented good early results and benefits of endoluminal stent graft repair of abdominal aortic aneurysm (J Vasc Surg 2002;35:1137-44.)(AAA), the long-term outcome of this method of treatment remains uncertain. In particular, concern exists that late effectiveness and durability are inferior to that of open repair. To determine the incidence and causes of clinical failures of endovascular AAA repair, a 7-year experience with 362 primary AAA endografts was reviewed. Clinical failures were defined as deaths within 30 days of the procedure, conversions (early and late) to open AAA repair, AAA rupture after endoluminal treatment, or AAA sac growth of more than 5 mm in maximal diameter despite endograft repair. Endoleak status per se was not considered unless it resulted in an adverse event. If clinical problems arose but could be corrected with catheter-based therapies or limited surgical procedures, thereby maintaining the integrity of successful stent graft treatment of the AAA, such cases were considered as primary assisted success and not classified as clinical failures. The average follow-up period was 1.5 years. Six deaths (1.6%) occurred after the procedure, all in elderly patients or patients at high risk. Five patients (1.4%) needed early conversion (immediate, 2 days) to open repair for access problems or technical difficulties with deployment, resulting in an implantation success rate of 98.6%. Eight patients (2.2%) underwent late conversion for a variety of problems, including AAA expansion (n = 4), endograft thrombosis (n = 1), secondary graft infection (n = 2), and rupture at 3 years (n = 1). Rupture occurred in an additional two patients for a total incidence rate of 0.8%. AAA sac growth of greater than 5 mm was observed in 20 patients (5.6%), four of whom have undergone successful catheter-based treatments to date. Overall, 39 patients (10.7%) needed catheter-based (n = 45) or limited surgical (n = 4) reinterventions for a variety of late problems that were successful in 92%. In our 7-year experience, one or more clinical failures of endovascular AAA repair were observed in 31 patients (8.3%). Reinterventions were necessitated in a total of 10.7% of patients but were usually successful in maintaining AAA exclusion and limiting AAA growth. These results emphasize that endovascular repair provides good results and many benefits for most properly selected patients but is not as durable as standard open repair.

Relationship between abdominal aortic aneurysm wall compliance and clinical outcome: a preliminary analysis

Aortic compliance, as measured by the pressure-strain elastic modulus (Ep) and stiffness (B), may allow a more precise estimate of abdominal aortic aneurysm rupture risk than size alone. To determine the relationships between AAA compliance, size, growth, and clinical outcome. One-hundred and twelve patients with initially non-operated AAA (86 men, 26 women, mean age 73 years), recruited from five centres, underwent baseline compliance measurements and were then followed for a median of 7 (range 2-18) months; 85 patients underwent repeated measurements (median 3, range 2-5) 3-6-monthly over a median of 12 (range 3-18 months). Seven patients have ruptured and 16 have undergone repair of non-ruptured AAA. AAA that ruptured had significantly lower Ep and B (more compliant). In AAA that ruptured or required repair there was an inverse relationship between diameter and Ep and B. In those undergoing repeated measurements AAA expansion was only associated with a significant increase in Ep and B in non-operated patients. Baseline AAA compliance was significantly related to rupture and the future requirement for operative repair. Failure of compliance to increase with size may be a marker for rapid growth, developmental symptoms and rupture.