Small Abdominal Aortic Aneurysms Research Articles

Characteristics and Outcomes of Ruptured Abdominal Aortic Aneurysms Below the Size Threshold for Elective Repair

The current guidelines recommend elective abdominal aortic aneurysm (AAA) repair at 5.5 cm in men and 5.0 cm in women. However, rupture can occur in patients with aneurysm below these size thresholds. This study aims to investigate the proportion of AAA that rupture below elective operative thresholds and compare the outcomes of repair to ruptured aneurysm at larger size in a national database. The American College of Surgeons National Surgical Quality Improvement Program targeted vascular files for open AAA repair and endovascular aneurysm repair (EVAR) were reviewed for all cases of ruptured AAA between 2011 and 2018. Patients were divided into two groups: small AAA for those that presented with ruptured aneurysms below current size guidelines and large AAA for those that met size criteria for elective repair. The proportion of infrarenal AAA between the two groups was determined. The comorbidities and perioperative outcomes of infrarenal AAA repair in both groups were compared. Of the 1612 ruptured AAA repairs, 167 (10.4%) were small AAAs. The proportion of small AAA ruptures did not significantly change during the study period (P = .15) (Figure). Patients in the large AAA group were more likely to have juxtarenal or suprarenal aneurysms compared to patients in the small AAA group (27% vs 16%; P = .001). Comparison of infrarenal AAA only demonstrated that the mean small AAA (n = 141) diameter was 4.41 (range, 2-5.4cm) compared to large AAA (n = 1051) mean diameter of 8.03 cm (range, 5-20 cm) (P < .01) (Table). Patients in the small AAA group had significantly lower body mass index and mean body weight and were more likely to present with hypotension compared to patients with large AAA. Patients in the small AAA group were more likely to have American Society of Anesthesiologists classification of ≤3 and to undergo EVAR. Repair of small ruptured aneurysms was also associated with lower bleeding, mortality, and mean operative time; but had higher readmissions rates. Multivariable regression demonstrated that dependent functional status (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.2-5.3), rupture with hypotension (OR, 3.4; 95% CI, 2.5-4.8), American Society of Anesthesiologists class ≥4 (OR, 2.5; 95% CI, 1.4-4.7), and open repair compared to EVAR (OR, 1.9; 95% CI, 1.3-2.6) were associated with increased mortality but not aneurysm size. Current guidelines for elective repair based solely on AAA sac diameter fail to identify at least 10% of patients that present with rupture. Rupture of infrarenal AAA carries significant mortality regardless of the size of the aneurysm at the time of rupture. Further research into sac morphology and more sensitive imaging modalities may help identify small AAA at high risk of rupture that would benefit from elective repair.TableCharacteristics of infrarenal small and large ruptured abdominal aortic aneurysm (AAA) repairsSmall AAAn = 141Large AAAn = 1051P valueAge, years.38 <503 (2.13)40 (3.81) 51-6429 (20.57)200 (19.03) 65-7942 (29.79)311 (29.59) 80+56 (39.72)371 (35.3) Mean ± standard deviation71.8 ± 11.6570.89 ± 11.84Sex.38 Male105 (74.47)817 (77.74)Functional status.16 Dependent8 (5.67)35 (3.33)BMI <1814 (9.93)95 (9.04).07 18-2447 (33.33)217 (20.65).17 25-3039 (27.66)282 (26.83).84 30-3412 (8.51)188 (17.89).07 35+16 (11.35)134 (12.75).38 Mean26.0527.77.02Mean height67.667.7.65Mean weight177.1191.4<.01Race White102 (72.34)790 (75.17).46 Other39 (27.66)261 (24.83)Comorbidities Diabetes mellitus22 (15.6)144 (13.7).54 Current smoker52 (36.88)401 (38.15).76 COPD26 (18.44)162 (15.41).35 CHF3 (2.13)32 (3.04).54 HTN106 (75.18)692 (65.84).02 Current dialysis3 (2.13)16 (1.52).59Presentation Mean AAA diameter (cm)4.41 ± 0.068.03 ± 0.06<.01 Rupture with hypotension47 (33.33)521 (49.57)<.01Surgical technique EVAR111 (78.72)685 (65.18)<.01 Open30 (21.28)366 (34.82)Principal anesthesia technique General126 (89.36)959 (91.25) Other15 (10.64)92 (8.75)ASA class.46 ≤342 (29.79)189 (17.98) ≥499 (70.21)862 (82.02)<.01Emergency case Yes102 (72.34)888 (84.49)<.01Mean operating time, minutes163.79 ± 8.99182.39 ± 8.99.03Adverse events Wound infection5 (3.55)36 (3.43).94 Pneumonia10 (7.09)100 (9.51).35 Unplanned intubation11 (7.8)93 (8.85).67 Failed vent weaning24 (17.02)224 (21.31).23 Cardiac arrest10 (7.09)103 (9.8).3 Myocardial infarction6 (4.26)90 (8.56).07 Stroke2 (1.42)20 (1.9).68 Bleeding77 (54.61)713 (67.84)<.01 DVT/thrombophlebitis4 (2.84)39 (3.71).6 Sepsis11 (7.8)108 (10.28).35 Renal failure1 (0.71)11 (1.05).7 Ischemic colitis8 (5.67)81 (7.71).38 Repeat repair of aneurysm7 (4.96)61 (5.8).68 Lower extremity ischemia3 (2.13)50 (4.76).15Any morbidity104 (73.76)808 (76.88).41Mortality24 (17.02)260 (24.74).04Readmission within 30 days19 (13.48)60 (5.71).005Reoperation23 (16.31)151 (14.37).53Hospital length of stay, days9.78 (12.20)9.71 (15.22).84ASA, American Society of Anesthesiologists,; BMI, body mass index; CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; DVT, deep vein thrombosis; EVAR, endovascular aneurysm repair; HTN, hypertension. 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Effect of Doxycycline on Aneurysm Growth Among Patients With Small Infrarenal Abdominal Aortic Aneurysms

Abdominal aortic aneurysms affect more than 3% of US older adults. To test whether doxycycline reduces the growth of abdominal aortic aneurysm over 2 years as measured by maximum transverse diameter. Parallel, 2-group, randomized clinical trial that was conducted at 22 US clinical centers between May 2013 and January 2017, and enrolled patients 50 years or older with small (3.5-5.0 cm for men, 3.5-4.5 cm for women) infrarenal aneurysms. The final date of follow-up was July 31, 2018. Patients were randomized to receive twice daily for 2 years doxycycline 100 mg orally (as capsules) (n = 133) or placebo (n = 128). The primary outcome was change in abdominal aortic aneurysm maximum transverse diameter measured from CT images at baseline and follow-up at 2 years. Patients were assigned ranks based on the maximum transverse diameter (measured or imputed) of the aorta and also if they underwent aneurysm repair or died. The ranks were converted to scores having a normal distribution to facilitate the primary analysis ("normal scores"). Of 261 patients randomized, no follow-up CT scans were obtained on 7 (3%), leaving a final analysis set of 129 patients assigned to doxycycline and 125 to placebo (mean [SD] age, 71.0 years [7.4 years], 35 women [14%]). The outcome normal scores used in the primary analysis were based on maximum transverse diameter (measured or imputed) in 113 patients (88%) in the doxycycline group and 112 patients (90%) in the placebo group; aneurysm repair in 13 (10%) and 9 (7%), and death in 3 (2%) and 4 (3%), respectively. The primary outcome, normal scores reflecting change in aortic diameter, did not differ significantly between the 2 groups, mean change in normal scores, 0.0262 vs -0.0258 (1-sided P = .71). Mean (SD) baseline maximum transverse diameter was 4.3 cm (0.4 cm) for doxycycline and 4.3 cm (0.4 cm) for placebo. At the 2-year follow-up, the change in measured maximum transverse diameter was 0.36 cm (95% CI, 0.31 to 0.40 cm) for 96 patients in the doxycycline group vs 0.36 cm (95% CI, 0.30 to 0.41 cm) for 101 patients in the placebo group (difference, 0.0; 95% CI, -0.07 to 0.07 cm; 2-sided P = .93). No patients were withdrawn from the study because of adverse effects. Joint pain occurred in 84 of 129 patients (65%) with doxycycline and 79 of 125 (63%) with placebo. Among patients with small infrarenal abdominal aortic aneurysms, doxycycline compared with placebo did not significantly reduce aneurysm growth at 2 years. These findings do not support the use of doxycycline for reducing the growth of small abdominal aortic aneurysms. ClinicalTrials.gov Identifier: NCT01756833.

The way forward to understand aortic disease.

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Intraluminal Thrombus Predicts Rapid Growth of Abdominal Aortic Aneurysms.

Background Intraluminal thrombus (ILT) within abdominal aortic aneurysms (AAAs) may be a potential marker for subsequent aneurysm growth. Purpose To investigate the role of ILT in AAA progression as assessed with CT and MRI. Materials and Methods This was a retrospective study, with patient data included from January 2004 to December 2018 at a Veteran Affairs medical center. Male patients with AAA who underwent contrast material-enhanced CT at baseline and CT or black-blood MRI at follow-up (minimal follow-up duration of 6 months) were included. The maximal AAA diameter was measured with multiplanar reconstruction, and the annual growth rate of aneurysms was calculated. Uni- and multivariable linear regression analyses were used to determine the relationship between demographic and imaging factors and aneurysm growth. Results A total of 225 patients (mean age, 72 years ± 9 [standard deviation]) were followed for a mean of 3.3 years ± 2.5. A total of 207 patients were followed up with CT, and 18 were followed up with MRI. At baseline, the median size of the AAA was 3.8 cm (interquartile range [IQR], 3.3-4.3 cm); 127 of 225 patients (54.7%) had ILT. When compared with AAAs without ILT, AAAs with ILT had larger baseline diameters (median, 4.1 cm [IQR, 3.6-4.8 cm] vs 3.4 cm [IQR, 3.2-3.9 cm]; P < .001) and faster growth rates (median, 2.0 mm/y [IQR, 1.3-3.2 mm/y] vs 1.0 mm/y [IQR, 0.4-1.8 mm/y]; P < .001). Small AAAs (size range, 3-4 cm) with ILT grew 1.9-fold faster than did those without ILT (median, 1.5 mm/y [IQR, 0.9-2.7 mm/y] vs 0.8 mm/y [IQR, 0.3-1.5 mm/y]; P < .001). Medium AAAs (size range, 4-5 cm) with ILT had 1.2-fold faster growth than did those without ILT (median growth, 2.1 mm/y [IQR, 1.4, 3.7 mm/y] vs 1.8 mm/y [IQR, 0.9, 2.0 mm/y]; P = .06). In multivariable analysis, baseline diameter and ILT were independently positively related to aneurysm growth rate (standardized regression coefficient, 0.43 [P < .001] and 0.15 [P = .02], respectively). Conclusion Both maximal cross-sectional aneurysm diameter and the presence of intraluminal thrombus are independent predictors of abdominal aortic aneurysm growth. © RSNA, 2020 Online supplemental material is available for this article.

The futility of surveillance for old and small aneurysms

ObjectiveWe investigated the yield of ultrasound surveillance for small abdominal aortic aneurysms (AAAs) in patients older than 80 years compared with a younger population for detecting AAA growth reaching the threshold size for repair. Secondary objectives included analysis of the incidence of AAA repair and the cost-benefit of surveillance. MethodsA retrospective cohort study was performed of all patients undergoing AAA surveillance in Ottawa between 2007 and 2015. Patients were dichotomized by enrollment age (<80 years vs ≥80 years) and stratified by enrollment AAA size. Cohorts were cross-referenced with the Ottawa surgical database, leveraging the common health region to ensure complete data capture. The threshold size for repair was sex specific (female, 5.0 cm; male, 5.5 cm). Factors influencing AAA growth rate were assessed with a general linear multiple mixed model. Analyses with Cox proportional hazards models with competing risk for mortality assessed aorta-related events, and cost-benefit was analyzed by referencing Ontario billing codes. ResultsA total of 1231 patients underwent serial ultrasound surveillance, of whom 500 were older than 80 years at some point during the study period. The mean AAA growth rate was 1.63 mm/y (95% confidence interval [CI], 1.54-1.71). Old age and small enrollment aneurysm size were significantly protective against AAA growth. Overall, 357 (29%) patients reached the AAA size threshold for repair, and 272 (22%) underwent AAA repair. Patients older than 80 years were less likely to reach the AAA threshold size for repair compared with their younger counterparts (adjusted hazard ratio, 0.77; 95% CI, 0.61-0.97). Of the 357 patients whose AAA reached the threshold size for repair, octogenarians were substantially less likely to undergo elective AAA repair (adjusted hazard ratio, 0.34; 95% CI, 0.24-0.47). Repair of ruptured AAA was rare (0.8%), and age differences were insignificant. For every octogenarian with an enrollment AAA size between 3.0 and 3.9 cm who ultimately received elective AAA repair, 51 patients were enrolled in surveillance without elective repair. This corresponded to an estimated $33,139 in ultrasound fees. ConclusionsSurveillance of most patients with small AAA is appropriate. However, patients older than 80 years were significantly less likely than their younger counterparts to experience aortic growth reaching the threshold size for repair. Furthermore, in the unlikely event of AAA growth, patients older than 80 years were substantially less likely to undergo repair. These results suggest that in the context of patient-specific health and wishes, surveillance of AAAs <4 cm in octogenarians is costly and unlikely to be beneficial.

Predicting abdominal aortic aneurysm growth using patient-oriented growth models with two-step Bayesian inference

ObjectiveFor small abdominal aortic aneurysms (AAAs), a regular follow-up examination is recommended every 12 months for AAAs of 30–39 mm and every six months for AAAs of 40–55 mm. Follow-up diameters can determine if a patient follows the common growth model of the population. However, the rapid expansion of an AAA, often associated with higher rupture risk, may be overlooked even though it requires surgical intervention. Therefore, the prognosis of abdominal aortic aneurysm growth is clinically important for planning treatment. This study aims to build enhanced Bayesian inference methods to predict maximum aneurysm diameter. Methods106 CT scans from 25 Korean AAA patients were retrospectively obtained. A two-step approach based on Bayesian calibration was used, and an exponential abdominal aortic aneurysm growth model (population-based) was specified according to each individual patient's growth (patient-specific) and morphologic characteristics of the aneurysm sac (enhanced). The distribution estimates were obtained using a Markov Chain Monte Carlo (MCMC) sampler. ResultsThe follow-up diameters were predicted satisfactorily (i.e. the true follow-up diameter was in the 95% prediction interval) for 79% of the scans using the population-based growth model, and 83% of the scans using the patient-specific growth model. Among the evaluated geometric measurements, centerline tortuosity was a significant (p = 0.0002) predictor of growth for AAAs with accelerated and stable expansion rates. Using the enhanced prediction model, 86% of follow-up scans were predicted satisfactorily. The average prediction errors of population-based, patient-specific, and enhanced models were ±2.67, ±2.61 and ± 2.79 mm, respectively. ConclusionA computational framework using patient-oriented growth models provides useful tools for per-patient basis treatment and enables better prediction of AAA growth.

Machine Learning to Predict the Rapid Growth of Small Abdominal Aortic Aneurysm.

The purpose of this study was to determine whether computed tomography (CT) angiography with machine learning (ML) can be used to predict the rapid growth of abdominal aortic aneurysm (AAA). This retrospective study was approved by our institutional review board. Fifty consecutive patients (45 men, 5 women, 73.5 years) with small AAA (38.5 ± 6.2 mm) had undergone CT angiography. To be included, patients required at least 2 CT scans a minimum of 6 months apart. Abdominal aortic aneurysm growth, estimated by change per year, was compared between patients with baseline infrarenal aortic minor axis. For each axial image, major axis of AAA, minor axis of AAA, major axis of lumen without intraluminal thrombi (ILT), minor axis of lumen without ILT, AAA area, lumen area without ILT, ILT area, maximum ILT area, and maximum ILT thickness were measured. We developed a prediction model using an ML method (to predict expansion >4 mm/y) and calculated the area under the receiver operating characteristic curve of this model via 10-fold cross-validation. The median aneurysm expansion was 3.0 mm/y. Major axis of AAA and AAA area correlated significantly with future AAA expansion (r = 0.472, 0.416 all P < 0.01). Machine learning and major axis of AAA were a strong predictor of significant AAA expansion (>4 mm/y) (area under the receiver operating characteristic curve were 0.86 and 0.78). Machine learning is an effective method for the prediction of expansion risk of AAA. Abdominal aortic aneurysm area and major axis of AAA are the important factors to reflect AAA expansion.

K-134, a phosphodiesterase 3 inhibitor, reduces vascular inflammation and hypoxia, and prevents rupture of experimental abdominal aortic aneurysms

ObjectiveAbdominal aortic aneurysm (AAA) is a chronic inflammatory disease, which frequently results in fatal rupture; however, no pharmacologic treatment exists to inhibit AAA growth and prevent rupture. In this study, we investigated whether K-134, a novel phosphodiesterase 3 inhibitor, could limit the progression and rupture of AAA using multiple experimental models. MethodsA hypoperfusion-induced AAA rat model was developed by inserting of a small catheter and via tight ligation of the infrarenal aorta. Rats were fed with a 0.15% K-134-containing diet (K-134(+) group) or a normal diet (K-134(-) group) from 7 days before the experiment to 28 days after model creation (pretreatment protocol). After the administration period, elastin fragmentation, macrophage infiltration, reactive oxygen species expression, matrix metalloproteinase levels, aneurysmal tissue hypoxia, and adventitial vasa vasorum (VV) stenosis were assessed. In the delayed treatment protocol, rats with AAA >3 mm were randomly divided to K-134(+) or K-134(-) group 7 days after model creation, and the effect of K-134 on suppressing preexisting AAA was examined. Further, elastase-induced rat model and angiotensin II-infused ApoE-/- mouse model were also used to examine the ability of K-134 to prevent rupture. ResultsK-134 prevented AAA rupture and significantly improved survival in the pretreatment protocol (P < .01). In the K-134(+) group, elastin degeneration was prevented; macrophage infiltration and reactive oxygen species production were significantly decreased. At 14 days, the enzymatic activity of matrix metalloproteinase-9 was significantly decreased. Further, K-134 inhibited intimal hyperplasia and VV stenosis. Expressions of hypoxic markers, hypoxia-inducible factor-1α, and pimonidazole, in the aneurysmal wall were also attenuated. In the delayed treatment protocol, K-134 also improved survival of rats with preexisting AAA. Similarly, in the elastase-induced rat model and angiotensin II-infused ApoE-/- mouse model, K-134 inhibited rupture and significantly improved survival (P < .01). ConclusionsK-134 prevented the rupture of AAA and improved survival through suppressing inflammatory reaction. The inhibition of intimal hyperplasia in the adventitial VV may be associated with reduced hypoxia in the aneurysmal tissue. (JVS–Vascular Science 2020;1:219-32.) Clinical RelevanceThis study shows that K-134, a novel phosphodiesterase 3 inhibitor, suppressed abdominal aortic aneurysm (AAA) rupture. Considering that K-134 had already undergone a phase Ⅱ study in the United States for claudication in peripheral artery occlusive disease patients with good tolerance, K-134 may become a promising new therapeutic option for AAAs and could undergo clinical trials for patients with small AAA.

Thrombosis of small abdominal aortic inflammatory aneurysm

Thrombosis of small abdominal aortic inflammatory aneurysm

Abdominal Aortic Aneurysm Rupture Risk Prediction Based on Computer-aided Vascular Wall Stress Assessment Using Finite Element Method – The Future of Decision Making Process

Introduction - Abdominal aortic aneurysm (AAA) is one of the most important conditions in vascular surgery1. Since in majority of cases AAA is asymptomatic often the first sign of AAA is its rupture with very high mortality, even when patient is urgently treated2. According the European guidelines3 when an asymptomatic AAA is identified the next course is directed only by its maximal diameter – if it is more than 5.5 cm an intervention is indicated. Despite the guidelines the literature says that 10-24 % of ruptured AAAs is less than 5.5 cm in diameter (small AAA)4. Clinical goal of this work was to determine a number of small ruptured AAAs and identification of possible risk factors leading to rupture small AAAs. Main goal of the project was to create an auxiliary diagnostic tool for AAA rupture risk assessment using 3D computer-aided modeling of AAA with vascular wall stress analysis using finite element method5 (FEM). Methods - The portion of small ruptured AAA was assessed in our center between years 2009-2016 together with possible risk factor for small AAA rupture. In the experimental part we describe the FEM and its use in vascular wall stress assessment of AAA. 3D computer model of AAA is created from CT angiographic images and wall stress is assessed using FEM and afterwards rupture risk is derived. Data gathered from mechanical tests of AAA wall specimens6 are used for making original mathematical more precise. This process was repeated with more than one hundred samples to get a model with the highest efficiency. Efficiency of the method was evaluated in blinded test confirming its ability to identify AAA with high risk of rupture (the set of CT images of both asymptomatic AAAs and ruptured AAAs from the time before the rupture was used). Results - Out of 90 patients with AAA rupture there were 15 with small AAA (16.7 %). Risk factors for AAA rupture were tested in our patient population and compared with literature. Female gender was not confirmed as a risk factor for small AAA rupture (contrary to literature)7, role of chronic obstructive pulmonary disease remains controversial and there was a significant correlation between number of ruptured AAA and the season of the year. Main outcome of the project is a functional diagnostic tool capable of AAA vascular stress analysis from CT findings and determination of rupture risk of particular AAA (Picture 1). Three criteria were compared according the efficiency and usefulness for clinical praxis (Peak Wall Rupture Risk, Probabilistic Rupture Risk Index and maximal diameter). Proving the Probabilistic Rupture Risk Index to be the best criterion according to efficiency and applicability. The discriminative powers of the predictors were 0.878, 0.859 and 0.789 respectively for PRRI, PWRR and the maximum diameter8. Conclusion - Portion of small ruptured AAA is clinically significant due to a high mortality of this condition. Current guidelines estimate the rupture risk based only on AAA diameter, but this criterion is not suitable for all AAA cases. Particular risk factors are describe in literature with controversial impact on AAA rupture risk, the same conclusion can be found in our patient population. New methods of vascular wall stress assessment using the 3D computer-aided modeling and FEM analysis have a strong potential to improve AAA rupture risk assessment and thus improve diagnostic and decision making process in clinical praxis. Supported by Ministry of Health of the Czech Republic grant no. 17-29701A. All rights reserved.

Intra-Luminal Thrombus Volume in Small Abdominal Aortic Aneurysms Assessed with Contrast Enhanced Three-Dimensional Ultrasound

Introduction - The intra-luminal thrombus (ILT) in abdominal aortic aneurysms (AAA) is suggested to weaken the aortic wall and contribute to aneurysm growth and eventually rupture (1–4). Thus, investigation of ILT has the potential to improve rupture risk prediction which today is predominantly based on diameter alone. Until recently, the ILT volume could only be determined by means of three-dimensional computed tomography angiography (3D-CTA) and ultrasound has not had a place in this context, although attractive due to its noninvasive nature. The primary aim of this study was to assess ILT volume using a novel ultrasound technology which combines three-dimensional ultrasound with contrast enhanced ultrasound (3D-CEUS) and compare these measures with 3D-CTA, using the latter as reference method. The second aim was to determine the reproducibility and repeatability of 3D-CEUS in ILT volume measurements. Methods - Between 1 January 2015 and 31 October 2016 (22 months), 143 patients with small asymptomatic AAA (US-diameter: 30-55 mm) were consecutively recruited. All patients underwent 3D-CEUS (Figure 1) and 3D-CTA the same day, in a mutually blinded setup. In total 15 patients were excluded due to CTA protocol deviation (n=2), inferior CEUS image quality (n=8) and AAA diameter > 55mm on US (n=5). Therefore, 128 patients (F/M; 22/106) with a mean AAA diameter of 45.1mm (SD ±6.2) were eligible for further analysis. Reproducibility assessment was performed on 30 patients who had an extra 3D-CEUS performed by a second physician. The ILT volume and maximum ILT thickness perpendicular to the AAA centerline was quantified off-line on a semi-automated quantification software (AAA-prototype v.2.0, Philips Research, Suresnes, France). Results - In 25 out of 128 patients, no ILT was found on 3D-CEUS, and confirmed on 3D-CTA analysis in all but one case. The mean ILT volume difference between 3D-CEUS and 3D-CT was 2.2ml (p=0.0001) equivalent to a 6% difference. The range of variability (ROV) was ±10.5ml. Likewise, the mean ILT thickness difference was 0.7mm (p= 0.002), with a ROV of ±4.5mm. The inter-observer variation of both ILT volume and ILT thickness measurement with 3D-CEUS was low, with reproducibility coefficients of 8.9ml and 3.0mm. A similar corresponding intra-observer variation of 7.5ml and 3.4mm, respectively, was found. Conclusion - Three-dimensional contrast enhanced ultrasound has demonstrated both good agreement and reproducibility in the assessment of ILT volume. It is expected that the method in the future can be implemented as a clinical tool in line with other advanced CEUS investigations. We foresee that ILT assessment with this novel ultrasound technique could be a valuable supplement in predicting rupture risk without radiation and nephrotoxic contrast agents.

Patients’ Experience of Living with a Small Abdominal Aortic Aneurysm and its Effect on Health Related Quality of Life While Being Under Surveillance: A Systematic Review and Synthesis

Introduction - Screening programs for finding a small abdominal aortic aneurysm (AAA) is a mean to prevent a sudden death in an undetected disease which can be prevented by surgery. Searching for a disease in asymptomatic people is however debated. There are ethical concerns of the potential risk that knowledge about the condition might do more harm than good and a discussion of ‘overdiagnosis’ has been the main argument against AAA screening. The aim of this study was to review the current knowledge on psychological impact, effect on health related quality of life and patients’ experience of living with an AAA, while being under surveillance. Methods - A systematic literature review of quantitative and qualitative studies including a narrative synthesis (similar to meta-analysis when merging data from randomized controlled trials), was performed according to PRISMA statement. PubMed, Embase, CRDs DARE, NHS EED, HTA and Cochrane Library were searched with the terms abdominal aortic aneurysm and screening in Mesh term combinations and covered time period 01 Jan 1990 to Dec 2017. The included studies were quality assessed according to the GRADE system. Separate syntheses were performed for the two sets of studies and were then converged into one overall synthesis. Results - A total of 17 studies were included; eleven with quantitative method using a case-control design and six with qualitative method using interview design. The quantitative studies included a total of 1720 patients with AAA and study size varied between 22 and 599 included. The qualitative studies included a total of 6o patients with AAA and study size varied between 3 and 15 included. No study had a follow-up period over 1 year. Overall quality was assessed as low for the quantitative studies and moderate for the qualitative studies. The overall synthesis is summarized as follows: 1) Patients with an AAA rate their General Health and dimensions related to physical functions as lower more often than people with normal aorta. 2) No difference in anxiety or depression for patients with AAA versus controls. 3) Patients felt safe being under surveillance and had trust in health-professionals. 4) Having an AAA set thoughts and feelings in motion regarding health, ageing, mortality and life-style. 5) Patients lack of knowledge about the AAA disease, its progression, physical training, life-style changes and future planning can cause insecurity and worries. Conclusion - The result shows no support that screening for AAA has an important negative psychological effect or a negative influence on HRQOL. Most studies had low-moderate quality, and high-quality studies controlling for co-morbidity as well as disease specific questionnaires are needed. Patients need for continuous information, education and care should be a priority clinical practice and should be further elucidated in future research.

Novel Markers of Rupture in Small Abdominal Aortic Aneurysms: Supra-renal Aortic Size Index and Peak Wall Rupture Index

Novel Markers of Rupture in Small Abdominal Aortic Aneurysms: Supra-renal Aortic Size Index and Peak Wall Rupture Index

Outcomes in a Prospective Cohort of Octogenarian and Nonagenarian Patients Diagnosed With a Small (&lt; 55 Mm) Abdominal Aortic Aneurysm: Rupture, Growth to a Large (&gt;=55 Mm) Size and Mortality Rates

Introduction: Due to longer population life expectancy and consistent improvement in diagnostic techniques, there has been a steady increase in the diagnosis of abdominal aortic aneurysms (AAA) in the older population in the last few decades. This tendency is expected to continue and the management of these patients is challenging. We aim to study the natural history of small (< 55 mm) AAA in octogenarian and nonagenarian patients in our health care area to assess the need for follow-up and/or invasive treatment. Methods: We performed a retrospective analysis of a prospective registry of all AAA diagnosed in our health area since 1988, selecting the patients of 80 or more years of age at the time of diagnosis of a small AAA in 1988-2018. We registered clinical and anatomical characteristics of the patients. We divided the patients in 3 groups: 30-39 mm AAA, 40-49 mm and 50-54 mm. The outcome variables were: aortoiliac rupture, AAA growth up to or beyond a surgical size (>=55 mm), and death. We performed a descriptive statistical analysis and compared the three groups, using life tables, Kaplan-Meier curves, uni and multivariate Cox regression. Results: We included 310 patients, 256 (82.6%) men, with mean age of 84.5 years (SD 3.5, range 80-96.3) at the time of diagnosis. The mean follow-up time was 41.6 months (SD 32.8, range 0-140.2). Seventeen (5.5%) AAA ruptured during follow-up; four of these patients were operated on and only one survived. Sixty (19.4%) AAA reached a surgical size; seven were electively repaired, with 0% early mortality. The survival rates for the complete cohort were 80%, 69% y 36% at 1, 2 and 5 years respectively. The rupture rates were 1%, 3% and 7% and the AAA which reached a surgical size were 2%, 5% and 19% for the same time periods. Men and women showed similar rupture rates, expansion rates to a surgical size and late mortality (p>0.05). The patients with 30-39 mm AAA had significantly smaller incidence of rupture (0.127; 95%CI 0.034-0.477; p=0.002) and late mortality rates (0.631; 95%CI 0.420-0.947; p=0.026), and decreased likelihood of reaching a surgical size (0.075; 95%CI 0.035-0.161; p< 0.0001). There were no significant differences between 40-49 mm and 50-54 mm AAA for the rupture and mortality rates (p>0.1), but 40-49 mm AAA were marginally less likely to reach a surgical size (0.581; 95%CI 0.322-1.047; p=0.071). Conclusion: The risk of late rupture of small AAA diagnosed in octogenarian and nonagenarian patients is very small, especially when the AAA is < 40 mm in diameter. In contrast, global mortality is high. Conservative management seems sensible, with strict selection of the patients who would benefit from follow-up and eventual repair. Disclosure: Nothing to disclose

Abdominal Aortic Aneurysms in the Ageing: Outcomes of Aneurysm Surveillance in 85 Year Olds

Introduction - By 2036 it is estimated that the number of people over the age of 85 years will double from present levels.1 This will have a profound impact on the management of complex vascular pathologies, such as abdominal aortic aneurysms (AAA). Despite this, the evidence relating to AAA surveillance was performed on patients aged less than 80 years and subsequently there is a paucity of evidence relating to the continued surveillance of this cohort.2 We aim to assess the outcomes of patients of 85 year olds who are under surveillance for small AAAs (3.0-5.5cm). Methods - A single-centre, retrospective analysis of all patients, aged 85 or over, undergoing active surveillance of small AAAs between January 2007-January 2018. Patients were stratified into four groups according to AAA diameter (<4.0, 4.0-4.5, 4.6-5.0, >5.0cm) at the age of 85 years (index scan), or older if first scan after this age. A comparison between the groups was performed to identify the rates of patients reaching threshold (>5.5cm), subsequent management and mortality (ruptured AAA and other cause mortality). Follow-up was continued from index scan to death or 01/01/2018 (whichever sooner). Results - 101 patients were identified (male=88) with a mean AAA diameter of 4.5cm (SD=0.92) at index scan. Mean follow-up was 1078 days (SD=739). 28 patients (27.7%) reached threshold size for repair, of which 8 (28.6%) underwent elective surgical repair. Of patients undergoing repair, 6(75%) had an AAA of >5cm at index scan. In patients with an AAA of <4.0cm at index, only 1 (3.4%) reached threshold and none underwent repair. Standard endovascular aneurysm repair was the modality of choice (62.5%). No patients underwent emergency repair. Comparison of outcomes between groups is shown in table 1. Overall mortality in the cohort was 26 (25.7%). Acute lower respiratory tract infection (42.3%) and cerebral vascular accident (23.1%) were the leading causes of death. Only 2 deaths occurred from ruptured AAAs (7.7%), both having an AAA of >5cm at index. No 30-day post-operative mortality was recorded.Table 1Comparison of patients reaching threshold and undergoing repairAneurysm diameter at aged 85 (cm)TotalTotal reaching threshold (% total)Surgical repair (% threshold)Mortality - ruptured aneurysm (% total)<4.0291 (3.4)0 (0.0)0 (0.0)4.0-4.5264 (15.4)1 (25.0)0 (0.0)4.6-5.0171 (5.9)1 (100)0 (0.0)>5.02922 (75.9)6 (27.3)2 (6.9) Open table in a new tab Conclusion - At the age of 85 years, it is very unlikely that patients with AAAs of <4cm will reach a threshold size for repair and discontinuation of surveillance can be considered. In our experience, the risk of death for a rupture in patients with AAAs 3.0-5.5cm at the age of 85 years remains relatively low and occurred only in patients with AAAs >5cm at index scan.

Magnetic Resonance Imaging Volumetric Assessment of Small Abdominal Aortic Aneurysm for Growth Monitoring – Implications for Power Calculation in Longitudinal Interventional Studies

Magnetic Resonance Imaging Volumetric Assessment of Small Abdominal Aortic Aneurysm for Growth Monitoring – Implications for Power Calculation in Longitudinal Interventional Studies

Assessment of International Outcomes of Intact Abdominal Aortic Aneurysm Repair over Nine Years

Introduction - Case mix and outcomes of complex surgical procedures vary over time and between regions.1 With noted increasing surgical activity and screening programmes for abdominal aortic aneurysm (AAA) detection and management, the monitoring of surgical outcome measures is increasingly important.2–4 The objective of this study is to describe trends in contemporary AAA practice in an international context, and assess the change in perioperative mortality after repair. Methods - Data on primary AAA repair from vascular surgery registries in 11 countries for the years 2005-2009 and 2010-2013 were analyzed. Data were analyzed overall, per country, per treatment (EVAR vs. open surgery), for high- and low-volume centres, and also between the two time periods (2005-2009 and 2010-2013). The primary outcome was perioperative mortality, defined as either in-hospital death or death within 30 days. Multivariable-adjusted logistic regression analyses were carried out to adjust for variations in case mix. Results - There were 83 253 patients included. Over the two periods, the proportion of patients ≥80 years old increased (18.5% vs. 23.1%; p<0.0001), as well as endovascular repair (EVAR) (44.3% vs. 60.6; p<0.0001). AAAs less than 5.5 cm in the latter period was 25.8%. The mean annual volume of open repairs per center decreased from 12.9 to 10.6 between the two periods, p<0.0001, while it increased for EVAR from 10.0 to 17.1, p<0.0001. Overall, perioperative mortality fell from 3.0% to 2.4% (p<0.0001). Mortality for EVAR decreased from 1.5% to 1.1% (p<0.0001), while the outcome worsened for open repair (3.9% vs. 4.4%, p=0.008). The perioperative risk was greater for octogenarians (Overall, 3.6% vs. 2.1%, p<0.0001; Open, 9.5% vs. 3.6%, p<0.0001; EVAR, 1.8% vs. 0.7%, p<0.0001), and women (Overall, 3.8% vs. 2.2%, p<0.0001; Open, 6.0% vs. 4.0%, p<0.0001; EVAR, 1.9% vs. 0.9%, p<0.0001). Perioperative mortality after repair of AAAs<5.5 cm was 4.4% with open repair and 1.0% with EVAR, p<0.0001. Conclusion - In this large international cohort, total perioperative mortality continues to fall for the treatment of intact AAAs. EVAR procedures now exceed the number of open procedures. Mortality after EVAR has decreased, while mortality for open operations has increased. The perioperative mortality for small AAA treatment, particularly open surgical repair, is still considerable and should be weighed against the risk of rupture. References1Beck AW, Sedrakyan A, Mao J, Venermo M, Faizer R, Debus S, et al. Variations in Abdominal Aortic Aneurysm Care: A Report from the International Consortium of Vascular Registries. Circulation 2016;134(24):1948–58.2Schwarze ML, Shen Y, Hemmerich J, Dale W. Age-related trends in utilization and outcome of open and endovascular repair for abdominal aortic aneurysm in the United States, 2001-2006. J Vasc Surg 2009;50(4):722-9.e2.3Chun KC, Teng KY, Van Spyk EN, Carson JG, Lee ES. Outcomes of an abdominal aortic aneurysm screening program. J Vasc Surg 2013;57(2):376–81.4Mani K, Lees T, Beiles B, Jensen LP, Venermo M, Simo G, et al. Treatment of abdominal aortic aneurysm in nine countries 2005-2009: A vascunet report. Eur J Vasc Endovasc Surg 2011;42(5):598–607.

The Expression Profile of MicroRNAs in Small and Large Abdominal Aortic Aneurysms.

Background Abdominal aortic aneurysms (AAA) are relatively frequent in elderly population, and their ruptures are related with high mortality rate. There are no actually used laboratory markers predicting the AAA development, course, and rupture. MicroRNAs are small noncoding molecules involved in posttranscriptional gene expression regulation, influencing processes on cell and tissue levels, and are actually in focus due to their potential to become diagnostic or prognostic markers in various diseases. Methods Tissue samples of AAA patients and healthy controls were collected, from which miRNA was isolated. Microarray including the complete panel of 2549 miRNAs was used to find expression miRNA profiles that were analysed in three subgroups: small (N = 10) and large (N = 6) aneurysms and healthy controls (N = 5). Fold changes between expression in aneurysms and normal tissue were calculated including corresponding p values, adjusted to multiple comparisons. Results Six miRNAs were found to be significantly dysregulated in small aneurysms (miR-7158-5p, miR-658, miR-517-5p, miR-122-5p, miR-326, and miR-3180) and 162 in large aneurysms, in comparison with the healthy control. Ten miRNAs in large aneurysms with more than two-fold significant change in expression were identified: miR-23a-3p, miR-24-3p, miR-27a-3p, miR-27b-3p, miR-30d-5p, miR-193a-3p, miR-203a-3p, miR-365a-3p, miR-4291, and miR-3663-3p and all, but the last one was downregulated in aneurysmal walls. Conclusion We confirmed some previously identified miRNAs (miR-23/27/24 family, miR-193a, and miR-30) as associated with AAA pathogenesis. We have found other, yet in AAA unidentified miRNAs (miR-203a, miR-3663, miR-365a, and miR-4291) for further analyses, to investigate more closely their possible role in pathogenesis of aneurysms. If their role in AAA development is proved significant in future, they can become potential markers or treatment targets.

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.

Comprehensive Cardiac Rehabilitation as a Therapeutic Strategy for Abdominal Aortic Aneurysm.

Abdominal aortic aneurysms (AAA) are referred to as “time bombs”. The only way to prevent AAA rupture is elective repair beforehand using surgical replacement or an endovascular procedure. Non-surgical strategies to prevent AAA expansion are under intense investigation. At each AAA stage, that is, occurrence, expansion, and rupture, the mechanisms and risk factors are different, as discussed in this review. Based on the mechanism and risk factors for AAA expansion, the most effective strategy against AAA expansion need to be identified, but so far none has. Exercise is known to be essential for preventing atherosclerosis related to the coexistence of AAA and CAD, but some doctors are hesitant to prescribe exercise programs to AAA patients given that BP elevation during exercise can cause AAA expansion or rupture. In our retrospective study and prospective study on the safety and effectiveness of exercise for AAA patients, the protective role of mild-moderate exercise against expansion of small AAA was clearly shown. The stability of AAA on exercise might be related to reduced inflammatory activity in the aortic wall, stabilized elevation in BP during exercise, increased aortic blood flow, upregulation of transforming growth factor-β1, moderated BMI and/or fat, or improved endothelial function. Until a revolutionary drug emerges that can regress AAA, cardiac rehabilitation remains the best strategy for preventing AAA expansion and rupture.