Rupture rates of untreated large abdominal aortic aneurysms in patients unfit for elective repair

Reassessing the operative threshold for abdominal aortic aneurysm repair in the context of COVID-19

OBJECTIVE

The worldwide pandemic involving the novel respiratory syndrome (COVID-19) has forced health care systems to delay elective operations, including abdominal aortic aneurysm (AAA) repair, to conserve resources. This study provides a structured analysis of the decision to delay AAA repair and quantify the potential for harm.

METHODS

A decision tree was constructed modeling immediate repair of AAA relative to an initial nonoperative (delayed repair) approach. Risks of COVID-19 contraction and mortality, aneurysm rupture, and operative mortality were considered. A deterministic sensitivity analysis for a range of patient ages (50 to >80), probability of COVID-19 infection (0.01%-30%), aneurysm size (5.5 to >7 cm), and time horizons (3-9 months) was performed. Probabilistic sensitivity analyses were conducted for three representative ages (60, 70, and 80). Analyses were conducted for endovascular aortic aneurysm repair (EVAR) and open surgical repair (OSR).

RESULTS

Patients with aneurysms 7 cm or greater demonstrated a higher probability of survival when treated with immediate EVAR or OSR, compared with delayed repair, for patients under 80 years of age. When considering EVAR for aneurysms 5.5 to 6.9 cm, immediate repair had a higher probability of survival except in settings with a high probability of COVID-19 infection (10%-30%) and advanced age (70-85+ years). A nonoperative strategy maximized the probability of survival as patient age or operative risk increased. Probabilistic sensitivity analyses demonstrated that patients with large aneurysms (>7 cm) faced a 5.4% to 7.7% absolute increase in the probability of mortality with a delay of repair of 3 months. Young patients (60-70 years) with aneurysms 6 to 6.9 cm demonstrated an elevated risk of mortality (1.5%-1.9%) with a delay of 3 months. Those with aneurysms 5 to 5.9 cm demonstrated an increased survival with immediate repair in young patients (60); however, this was small in magnitude (0.2%-0.8%). The potential for harm increased as the length of surgical delay increased. For elderly patients requiring OSR, in the context of endemic COVID-19, delay of repair improves the probability of survival.

CONCLUSIONS

The decision to delay operative repair of AAA should consider both patient age and local COVID-19 prevalence in addition to aneurysm size. EVAR should be considered when possible due to a reduced risk of harm and lower resource utilization.

Sex Differences in Rupture Risk and Mortality in Untreated Patients With Intact Abdominal Aortic Aneurysms

Background

Studies on intact abdominal aortic aneurysms mainly focus on treated patients, and data on untreated patients are sparse. The objective was to investigate sex differences among untreated patients regarding rupture and mortality rates and to determine predictors for these events. Sex‐specific causes of death were evaluated.

Methods and Results

All patients ≥40 years diagnosed from 2001 to 2015 (n=32 393) with intact abdominal aortic aneurysms were identified in national registries; 60% (n=19 569) were untreated. Comorbid loads, crude rupture, and mortality rates were assessed. Predictors of 5‐year rupture and mortality were analyzed in Cox models (sex, age, comorbidities, income, and marital status). The proportion of men and women with multiple comorbidities was similar. Within 5 years, 798 ruptures occurred (9.7% women versus 6.9% men, P<0.001). Ruptures were independently predicted by female sex (hazard ratio [HR], 1.23; 95% CI, 1.07–1.42; P=0.004), chronic obstructive pulmonary disease (HR, 1.36; 95% CI, 1.15–1.62; P<0.001), age (HR, 11.49; 95% CI, 5.68–23.25 for ≥80 years; P<0.001), and income (HR, 0.63; 95% CI, 0.53–0.75 for highest tertile; P<0.001). After 5 years, 56.5% women and 50.4% men were deceased. Mortality was not independently predicted by female sex. Rupture was the third most common cause of death (11.9% women versus 8.7% men; P<0.001). The median time‐to‐events was 2.8 years.

Conclusions

A considerable proportion of patients with intact abdominal aortic aneurysms in surveillance remain untreated. Despite surveillance algorithms, the healthcare system fails to prevent a high number of ruptures, especially among women. The time‐to‐event data highlight the urgency to develop more individualized surveillance.

Development of three different decision support tools to support shared decision-making in vascular surgery

BACKGROUND

Shared decision-making (SDM) is known to improve quality of care. Particularly in vascular surgery treatment options are often preference-sensitive. Unfortunately, vascular surgeons infrequently apply SDM. Decision support tools (DSTs) have been shown to be helpful in SDM.

OBJECTIVE

This article describes the development process of three different DSTs to help vascular surgeons and patients apply SDM.

PATIENT INVOLVEMENT

Patients' information needs were obtained via focus group meetings. Fifty-two patients and eighteen vascular surgeons not involved in the development process evaluated the comprehensibility and usability of the DST-prototypes.

METHODS

A multidisciplinary steering group commissioned the development of the three DSTs according to international standards.

RESULTS

Digital decision aids and paper-based consultation cards and decision cards were developed for patients with an abdominal aortic aneurysm, carotid artery disease, intermittent claudication or varicose veins. Patients preferred the use of the decision aids followed by consultation cards, whereas vascular surgeons preferred to use decision cards followed by decision aids.

DISCUSSION

Decision aids, consultation cards and decision cards for four vascular diseases are now available to all vascular surgeons and patients in the Netherlands. The DSTs were well received by both surgeons and patients. English versions are also available.

Fully automatic volume segmentation of infrarenal abdominal aortic aneurysm computed tomography images with deep learning approaches versus physician controlled manual segmentation

OBJECTIVE

Imaging software has become critical tools in the diagnosis and decision making for the treatment of abdominal aortic aneurysms (AAA). However, the interobserver reproducibility of the maximum cross-section diameter is poor. This study aimed to present and assess the quality of a new fully automated software (PRAEVAorta) that enables fast and robust detection of the aortic lumen and the infrarenal AAA characteristics including the presence of thrombus.

METHODS

To evaluate the segmentation obtained with this new software, we performed a quantitative comparison with the results obtained from a semiautomatic segmentation manually corrected by a senior and a junior surgeon on a dataset of 100 preoperative computed tomography angiographies from patients with infrarenal AAAs (13,465 slices). The Dice similarity coefficient (DSC), Jaccard index, sensitivity, specificity, volumetric similarity (VS), Hausdorff distance, maximum aortic transverse diameter, and the duration of segmentation were calculated between the two methods and, for the semiautomatic software, also between the two observers.

RESULTS

The analyses demonstrated an excellent correlation of the volumes, surfaces, and diameters measured with the fully automatic and manually corrected segmentation methods, with a Pearson's coefficient correlation of greater than 0.90 (P < .0001). Overall, a comparison between the fully automatic and manually corrected segmentation method by the senior surgeon revealed a mean Dice similarity coefficient of 0.95 ± 0.01, a Jaccard index of 0.91 ± 0.02, sensitivity of 0.94 ± 0.02, specificity of 0.97 ± 0.01, VS of 0.98 ± 0.01, and mean Hausdorff distance per slice of 4.61 ± 7.26 mm. The mean VS reached 0.95 ± 0.04 for the lumen and 0.91 ± 0.07 for the thrombus. For the fully automatic method, the segmentation time varied from 27 seconds to 4 minutes per patient vs 5 minutes to 80 minutes for the manually corrected methods (P < .0001).

CONCLUSIONS

By enabling a fast and fully automated detailed analysis of the anatomic characteristics of infrarenal AAAs, this software could have strong applications in daily clinical practice and clinical research.

Development and internal validation of a prognostic model for mortality of patients with abdominal aortic aneurysms treated with endovascular aneurysm repair

Background: Morbidity and mortality associated with elective endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAA) must be balanced against the impending risk of aneurysm rupture and the estimated remaining lifetime. The aim of this study is to develop and validate a prognostic model for mortality of patients with AAA treated with EVAR. Methods: This retrospective observational study included 251 consecutive patients treated with EVAR for asymptomatic AAA between January 2001 and December 2012 at the University Hospital in Bern, Switzerland. Pre-selection of variables was based on a literature review; least absolute shrinkage and selection operator technique was used for the final variable selection. A Firth's bias reduced Cox proportional hazard model was developed and validated using 10,000 bootstrap samples to predict survival after EVAR. Results: The median follow-up time was 5.3 years (range 0.1 to 15.9). At the study closing date 95% of follow-up information was available. The mortality rates were 31.9% at 5 years and 50.5% at the study closing date, respectively. Identified predictors for overall mortality after EVAR were age, hazard ratio (HR) = 2.24 per 10-year increase (95% CI 1.64 to 3.09), the presence of chronic obstructive pulmonary disease (COPD), HR = 2.22 (95% CI 1.48 to 3.31), and lower estimated glomerular filtration rate, HR = 1.24 per 10 ml/min/1.73 m² decrease (95% CI 1.12 to 1.39). The model showed good discrimination ability, Harrell's C = 0.722 (95% CI 0.667 to 0.778) and was very robust in the bootstrap in-sample validation Harrell's C = 0.726 (95% CI 0.662 to 0.788). Conclusion: Higher age, the presence of COPD and impaired kidney function are independent predictors for impaired survival after EVAR. The expected remaining lifetime should be considered in patients with AAA. This prognostic model can help improving patient care; however, external validation is needed prior to clinical implementation.

Contemporary outcomes of endovascular abdominal aortic aneurysm repair in patients deemed unfit for open surgical repair

OBJECTIVE

Endovascular abdominal aortic aneurysm repair (EVAR) has been preferred to open surgical repair (OSR) for the treatment of abdominal aortic aneurysms (AAAs) in high-risk patients. We compared the perioperative and long-term outcomes of EVAR for patients designated as unfit for OSR using a large national dataset.

METHODS

The Vascular Quality Initiative database was queried for patients who had undergone elective EVAR for AAAs >5 cm from 2013 to 2019. The patients were stratified into two cohorts according to their suitability for OSR (fit vs unfit). The primary outcomes included perioperative (in-hospital) major adverse events, perioperative mortality, and mortality at 1 and 5 years. Patient demographics and postoperative outcomes were analyzed to identify the predictors of perioperative and long-term mortality.

RESULTS

Of 16,183 EVARs, 1782 patients had been deemed unfit for OSR. The unfit cohort was more likely to be older and female, with a greater proportion of hypertension, coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease, and larger aneurysm diameters. Postoperatively, the unfit cohort was more likely to have experienced cardiopulmonary complications (6.5% vs 3%; P < .001), with greater perioperative mortality (1.7% vs 0.6%; P < .001) and 1- and 5-year mortality (13% and 29% for the unfit vs 5% and 14% for the fit cohorts, respectively; P < .001). A subgroup analysis of the unfit cohort revealed that those deemed unfit because of a hostile abdomen had significantly lower 1- and 5-year mortality (6% and 20%, respectively) compared with those considered unfit because of cardiopulmonary compromise and frailty (14% and 30%, respectively; P = .451). Reintervention-free survival at 1 and 5 years was significantly greater in the fit cohort (93% and 82%, respectively) compared with that for the unfit cohort (85% and 68%, respectively; P < .001). The designation as unfit for OSR was an independent predictor of both perioperative (odds ratio, 1.59; 95% confidence interval [CI], 1.03-2.46; P = .038) and long-term mortality (hazard ratio [HR], 1.92; 95% CI, 1.69-2.17; P < .001). Advanced age (odds ratio, 2.91; 95% CI, 1.28-6.66; P = .011) was the strongest determinant of perioperative mortality, and end-stage renal disease (HR, 2.51; 95% CI, 1.78-3.55; P < .001) was the strongest predictor of long-term mortality. Statin use (HR, 0.77; 95% CI, 0.69-0.87; P < .001) and angiotensin-converting enzyme inhibitor use (HR, 0.83; 95% CI, 0.75-0.93; P < .001) were protective of long-term mortality.

CONCLUSIONS

Despite low perioperative mortality, the long-term mortality of those designated by operating surgeons as unfit for OSR was rather high for patients undergoing elective EVAR, likely owing to the competing risk of death from medical frailty. An unfit designation because of a hostile abdomen did not confer any additional risks after EVAR. Judicious estimation of the patient's life expectancy is essential when considering the treatment options for this subset of patients deemed unfit for OSR.

Risk Factors and Mouse Models of Abdominal Aortic Aneurysm Rupture

Abdominal aortic aneurysm (AAA) rupture is an important cause of death in older adults. In clinical practice, the most established predictor of AAA rupture is maximum AAA diameter. Aortic diameter is commonly used to assess AAA severity in mouse models studies. AAA rupture occurs when the stress (force per unit area) on the aneurysm wall exceeds wall strength. Previous research suggests that aortic wall structure and strength, biomechanical forces on the aorta and cellular and proteolytic composition of the AAA wall influence the risk of AAA rupture. Mouse models offer an opportunity to study the association of these factors with AAA rupture in a way not currently possible in patients. Such studies could provide data to support the use of novel surrogate markers of AAA rupture in patients. In this review, the currently available mouse models of AAA and their relevance to the study of AAA rupture are discussed. The review highlights the limitations of mouse models and suggests novel approaches that could be incorporated in future experimental AAA studies to generate clinically relevant results.

Analysis of Endovascular Aneurysm Repair for Small Abdominal Aortic Aneurysms in Males

BACKGROUND

Current guidelines recommend repair of abdominal aortic aneurysms (AAAs) when ≥5.5 cm. This study sought to evaluate the incidence of male patients undergoing endovascular aneurysm repair (EVAR) for AAAs of various diameters (small <4 cm; intermediate 4-5.4 cm; standard ≥5.5 cm). We analyzed predictors of mortality, hypothesizing that smaller AAAs (<5.5 cm) have no differences in associated risk of mortality compared to standard AAAs (≥5.5 cm).

METHODS

The 2011-2017 American College of Surgeons National Surgical Quality Improvement Program Procedure-Targeted Vascular database was queried for male patients undergoing elective EVAR. Patients were stratified by aneurysm diameter. A multivariable logistic regression analysis for clinical outcomes, adjusting for age, clinical characteristics, and comorbidities, was performed.

RESULTS

A total of 8037 male patients underwent EVAR with 3926 (48.9%) performed for AAAs <5.5 cm. There was no difference in mortality, readmission, major complications, myocardial infarction, stroke, or ischemic complications among the 3 groups (P > 0.05). In AAAs <5.5 cm, predictors of mortality included prior abdominal surgery (odds ratio [OR], 5.77; confidence interval [CI], 1.38-24.13; P = 0.016), weight loss (OR, 43.4; CI, 3.78-498.7; P = 0.002), disseminated cancer (OR, 17.9; CI, 1.30-245.97; P = 0.031), and diabetes (OR, 6.09; CI, 1.52-24.36; P = 0.011).

CONCLUSIONS

Nearly 50% of male patients undergoing elective EVAR were treated for AAAs <5.5 cm. There was no difference in associated risk of mortality for smaller AAAs compared to standard AAAs. The strongest predictors of mortality for patients with smaller AAAs were prior abdominal surgery, weight loss, disseminated cancer, and diabetes.

Extended screening guidelines for the diagnosis of abdominal aortic aneurysm

BACKGROUND

The U.S. Preventive Services Task Force (USPSTF) guidelines are the most widely used criteria for screening for abdominal aortic aneurysms (AAA). However, when the USPSTF criteria are applied retrospectively to a group of patients who have undergone treatment for AAA, there are many patients who satisfy none of the AAA screening criteria. The more sensitive Society for Vascular Surgery (SVS) guidelines have expanded the criteria for screening for AAA with the hope of capturing a greater fraction of those individuals who can undergo treatment for their AAA before presenting with AAA rupture. We sought to identify the number of patients who would have been identified as having criteria for screening for AAA by both the USPSTF and SVS criteria, in a cohort of patients who have undergone treatment for AAA.

METHODS

We assessed demographic, comorbidity, and perioperative complication data for all patients undergoing endovascular and open AAA repair in the Vascular Quality Initiative. Patients meeting each of the screening criteria were identified. Clinical factors and demographic variables were collected.

RESULTS

We identified 55,197 patients undergoing AAA repair in the Vascular Quality Initiative, including 44,602 patients who underwent endovascular aneurysm repair (EVAR) and 10,595 patients undergoing open repair. Of these, the USPTF guidelines would have identified fewer than one-third of patients (32% EVAR and 33% open repair). Applying the SVS guidelines increased the number meeting criteria for screening by 6% and 12% for the EVAR and open repair cohorts, respectively. Finally, adoption of the expanded SVS guidelines (including the "weak recommendations") would have identified an additional 34% of EVAR patients and 21% of open AAA repair patients. Use of the expanded criteria would have resulted in 27% of patients undergoing EVAR and 33% of patients undergoing open AAA repair who would not have met any screening criteria. In EVAR patients not meeting the criteria, 52% were younger than 65 years had a history of heavy smoking. Of all those who did not meet screening criteria, ruptured AAA was twice as prevalent as those who met screening criteria (8.5% vs 4.4%; P ≤ .0001).

CONCLUSIONS

Expanding established USPSTF screening guidelines to include the expanded SVS criteria may potentially double the number of patients identified with AAA. Smokers under the age of 65, and elderly patients 70 and older with no smoking history, represent two groups with AAA and potentially twice the risk of presenting with rupture.

Editor's Choice - Assessment of Correlation Between Mean Size of Infrarenal Abdominal Aortic Aneurysm at Time of Intact Repair Against Repair and Rupture Rate in Nine Countries

OBJECTIVE

This study aimed to analyse the mean abdominal aortic aneurysm (AAA) diameter for repair in nine countries, and to determine variation in mean AAA diameter for elective AAA repair and its relationship to rupture AAA repair rates and aneurysm related mortality in corresponding populations.

METHODS

Data on intact (iAAA) and ruptured infrarenal AAA (rAAA) repair for the years 2010-2012 were collected from Denmark, England, Finland, Germany, Hungary, New Zealand, Norway, Sweden, and the USA. The rate of iAAA repair and rAAA per 100 000 inhabitants above 59 years old, mean AAA diameter for iAAA repair and rAAA repair, and the national rates of rAAA were assessed. National cause of death statistics were used to estimate aneurysm related mortality. Direct standardisation methods were applied to the national mortality data. Logistic regression and analysis of variance model adjustments were made for age groups, sex, and year.

RESULTS

There was a variation in the mean diameter of iAAA repair (n = 34 566; range Germany = 57 mm, Denmark = 68 mm). The standardised iAAA repair rate per 100000 inhabitants varied from 10.4 (Hungary) to 66.5 (Norway), p<.01, and the standardised rAAA repair rate per 100 000 from 5.8 (USA) to 16.9 (England), p<.01. Overall, there was no significant correlation between mean diameter of iAAA repair and standardised iAAA rate (r² = 0.04, p = .3). There was no significant correlation between rAAA repair rate (n = 12 628) with mean diameter of iAAA repair (r² = 0.2, p = .1).

CONCLUSION

Despite recommendations from learned society guidelines, data indicate variations in mean diameter for AAA repair. There was no significant correlation between mean diameter of AAA repair and rates of iAAA repair and rAAA repair. These analyses are subject to differences in disease prevalence, uncertainties in rupture rates, validations of vascular registries, causes of death and registrations.

Aspartate transaminase to platelet ratio index and Model for End-Stage Liver Disease scores are associated with morbidity and mortality after endovascular aneurysm repair among patients with liver dysfunction

BACKGROUND

Liver cirrhosis dramatically increases morbidity and mortality after open surgical procedures and is often a contraindication to open repair of abdominal aortic aneurysms. However, limited data have evaluated the effect of liver disease on outcomes after endovascular repair of aortic aneurysms.

METHODS

The National Surgical Quality Improvement Program was used to evaluate all nonemergent endovascular aneurysm repairs (EVARs) from 2005 to 2016. The aspartate transaminase to platelet ratio index is a sensitive, noninvasive screening tool used to screen for liver disease and was calculated for all patients. A value >0.5 was used to identify those with significant liver fibrosis. Demographics, comorbidities, and 30-day outcomes were then compared between patients with and patients without fibrosis. Additional analysis was then completed to assess the effect of increasing Model for End-Stage Liver Disease (MELD) score on 30-day outcomes. Multivariable regression was used to account for differences in baseline factors.

RESULTS

EVAR was performed on 18,484 patients including 2286 with liver fibrosis and 16,198 without. Patients with liver fibrosis had an increased 30-day mortality (1.5% vs 2.4%; P < .01) and significantly higher rates of major morbidities including return to the operating room, pulmonary complications, transfusion, and discharge other than home. After multivariable analysis, patients with liver fibrosis had a significant increase in 30-day mortality (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.1-2.1), return to the operating room (OR, 1.5; 95% CI, 1.2-1.8), pulmonary complications (OR, 1.6; 95% CI, 1.2-2.0), transfusion (OR, 1.7; 95% CI, 1.5-2.0), and discharge other than home (OR, 1.5; 95% CI, 1.3-1.8). In further analysis, mortality also increased in a stepwise fashion with increasing MELD score (MELD <10, 1.3%; MELD 10-15, 2.3%; MELD >15, 4.7%; P < .01), as did major complications (MELD <10, 7%; MELD 10-15, 11%; MELD >15, 15%; P < .01). These increases persisted in adjusted analysis.

CONCLUSIONS

Liver fibrosis significantly increases mortality and major morbidity after EVAR. The aspartate transaminase to platelet ratio index and MELD score should be used for preoperative risk stratification. Moreover, current 30-day morbidity and mortality rates among patients with MELD scores >10 exceed 5%, which is higher than the annual rupture risk for aneurysms <6 cm. Therefore, an increased size threshold of >6 cm may be warranted before EVAR in patients with liver fibrosis.

Plasma Desmosine and Abdominal Aortic Aneurysm Disease

Background

It is recognized that factors beyond aortic size are important in predicting outcome in abdominal aortic aneurysm (AAA) disease. AAA is characterized by the breakdown of elastin within the aortic tunica media, leading to aortic dilatation and rupture. The aim of this study was to investigate the association of plasma desmosine (pDES), an elastin‐specific degradation product, with disease severity and clinical outcome in patients with AAA.

Methods and Results

We measured pDES and serum biomarker concentrations in 507 patients with AAAs (94% men; mean age, 72.4±6.1 years; mean AAA diameter, 48±8 mm) and 162 control subjects (100% men; mean age, 71.5±4.4 years) from 2 observational cohort studies. In the longitudinal cohort study (n=239), we explored the incremental prognostic value of pDES on AAA events. pDES was higher in patients with AAA compared with control subjects (mean±SD: 0.46±0.22 versus 0.33±0.16 ng/mL; P<0.001) and had the strongest correlation with AAA diameter (r=0.39; P<0.0001) of any serum biomarker. After adjustment for baseline AAA diameter, pDES was associated with an AAA event (hazard ratio, 2.03 per SD increase [95% CI, 1.02–4.02]; P=0.044). In addition to AAA diameter, pDES provided incremental improvement in risk stratification (continuous net reclassification improvement, 34.4% [95% CI, −10.8% to 57.5%; P=0.09]; integrated discrimination improvement, 0.04 [95% CI, 0.00–0.15; P=0.050]).

Conclusions

pDES concentrations predict disease severity and clinical outcomes in patients with AAA.

Clinical Trial Registration

http://www.isrctn.com. Unique identifier: ISRCTN76413758.

A large proportion of patients with small ruptured abdominal aortic aneurysms are women and have chronic obstructive pulmonary disease

Objective

In a population-based cohort of ruptured abdominal aortic aneurysms (rAAAs), our aim was to investigate clinical, morphological and biomechanical features in patients with small rAAAs.

Methods

All patients admitted to an emergency department in Stockholm and Gotland, a region with a population of 2.1 million, between 2009–2013 with a CT-verified rupture (n = 192) were included, and morphological measurements were performed. Patients with small rAAAs, maximal diameter (Dmax) ≤ 60 mm were selected (n = 27), and matched 2:1 by Dmax, sex and age to intact AAA (iAAAs). For these patients, morphology including volume and finite element analysis-derived biomechanics were assessed.

Results

The mean Dmax for all rAAAs was 80.8 mm (SD = 18.9 mm), women had smaller Dmax at rupture (73.4 ± 18.4 mm vs 83.1 ± 18.5 mm, p = 0.003), and smaller neck and iliac diameters compared to men. Aortic size index (ASI) was similar between men and women (4.1 ± 3.1 cm/m² vs 3.8 ± 1.0 cm/m²). Fourteen percent of all patients ruptured at Dmax ≤ 60 mm, and a higher proportion of women compared to men ruptured at Dmax ≤ 60 mm: 27% (12/45) vs. 10% (15/147), p = 0.005. Also, a higher proportion of patients with a chronic obstructive pulmonary disease ruptured at Dmax ≤ 60 mm (34.6% vs 14.6%, p = 0.026). Supra-renal aortic size index (14.0, IQR 13.3–15.3 vs 12.8, IQR = 11.4–14.0) and peak wall rupture index (PWRI, 0.35 ± 0.08 vs 0.43 ± 0.11, p = 0.016) were higher for small rAAAs compared to matched iAAAs. Aortic size index, peak wall stress and aneurysm volume did not differ.

Conclusion

More than one tenth of ruptures occur at smaller diameters, women continuously suffer an even higher risk of presenting with smaller diameters, and this must be considered in surveillance programs. The increased supra-renal aortic size index and PWRI are potential markers for rupture risk, and patients under surveillance with these markers may benefit from increased attention, and potentially from timely repair.

Variation in center-level frailty burden and the impact of frailty on long-term survival in patients undergoing elective repair for abdominal aortic aneurysms

OBJECTIVE

Frailty is increasingly recognized as a key determinant in predicting postoperative outcomes. Centers that see more frail patients may not be captured in risk adjustment, potentially accounting for poorer outcomes in hospital comparisons. We aimed to (1) determine the effect of frailty on long-term mortality in patients undergoing elective abdominal aortic aneurysm (AAA) repair and (2) evaluate the variability in frailty burden among centers in the Vascular Quality Initiative (VQI) database.

METHODS

Patients undergoing elective open and endovascular AAA repair (2003-2017) were identified, and those with complete data on component variables of the VQI-derived Risk Analysis Index (VQI-RAI) and centers with ≥10 AAA repairs were included. VQI-RAI characteristics are sex, age, body mass index, renal failure, congestive heart failure, dyspnea, preoperative ambulation, and functional status. Frailty was defined as VQI-RAI ≥35 based on prior work in surgical patients using other quality improvement databases. This corresponds to the top 12% of patients at risk in the VQI. Center-level VQI-RAI differences were assessed by analysis of variance test. Relationships between frailty and survival were compared by Kaplan-Meier analysis and the log-rank test for open and endovascular procedures. Multivariable hierarchical Cox proportional hazards regression models were calculated with random intercepts for center, controlling for frailty, race, insurance, AAA diameter, procedure type, AAA case mix, and year.

RESULTS

A total of 15,803 patients from 185 centers were included. Mean VQI-RAI scores were 27.6 (standard deviation, 5.9; range, 4-56) and varied significantly across centers (F = 2.41, P < .001). The percentage of frail patients per center ranged from 0% to 40.0%. In multivariable analysis, frailty was independently associated with long-term mortality (hazard ratio, 2.88; 95% confidence interval, 2.6-3.2) after accounting for covariates and center-level variance. Open AAA repair was not associated with long-term mortality after adjusting for frailty (hazard ratio, 0.98; 95% confidence interval, 0.86-1.13). There was a statistically significant difference in the percentage of frail patients compared with nonfrail patients who were discharged to a rehabilitation facility or nursing home after both open (40.5% vs 17.8%; P < .0001) and endovascular repair (17.7% vs 4.6%; P < .0001).

CONCLUSIONS

There is considerable variability of preoperative frailty among VQI centers performing elective AAA repair. Adjusting for center-level variation, frailty but not procedure type had a significant association with long-term mortality; however, frailty and procedure type were both associated with nonhome discharge. Routine measurement of frailty preoperatively by centers to identify high-risk patients may help mitigate procedural and long-term outcomes and improve shared decision-making regarding AAA repair.

Validation of a preoperative prediction model for mortality within 1 year after endovascular aortic aneurysm repair of intact aneurysms

OBJECTIVE

Most would agree that at least 1-year survival is necessary after intact abdominal aortic aneurysm (AAA) repair to appropriately justify the cost and risk of the procedure. No validated clinical decision instruments exist to predict survival after endovascular aneurysm repair (EVAR) beyond the perioperative period. The purpose of this analysis was to create a preoperative prediction model for 1-year mortality after EVAR for intact AAA in the Society for Vascular Surgery Vascular Quality Initiative.

METHODS

All intact EVARs in the Society for Vascular Surgery Vascular Quality Initiative from 2011 to 2015 were randomly divided into training (n = 17,836) and validation (n = 2500) data sets, and 31 preoperative candidate predictors were identified. A logistic regression model for 1-year mortality was created, and bootstrapped stepwise variable elimination was used to reduce this model to a best subset of predictors. Penalized maximum likelihood estimation was used to correct for potential overfitting. The final model was internally validated by bootstrapping the area under the curve (AUC) and the calibration slope and intercept, and its performance when applied to the training and validation data sets was compared.

RESULTS

After elective and nonelective (symptomatic, intact) EVAR, 1-year mortality was 5.5% (n = 900/16,411) and 11.4% (n = 162/1425), respectively. The mean probability of 1-year mortality was 6.0% (n = 1062) in the training set and 5.7% (n = 143) in the validation cohort (P = .12). Significant preoperative predictors of 1-year mortality included chronic obstructive pulmonary disease, age, preoperative renal insufficiency (creatinine concentration ≥1.8 mg/dL or on hemodialysis), ejection fraction <50%, transfer status, body mass index <24 kg/m², preoperative beta-blocker exposure, larger AAA diameter, and lower admission hemoglobin level. Preoperative statin use was found to be protective. The bias-corrected AUC was 0.759 (Hosmer-Lemeshow goodness-of-fit P value of 0.36; calibration intercept, -0.003; slope, 0.999). When applied to the validation data set, the model had AUC of 0.724 (95% confidence interval, 0.676-0.768; calibration intercept, 0.0009; slope, 0.970), which was in excellent agreement with the original data set bias-corrected AUC. Notably, ∼27.5% (n = 4902) had four or more risk factors with a predicted 1-year post-EVAR mortality risk of 10% to 22% despite that 33.2% of these patients had AAA diameters below recommended treatment guideline minimum thresholds.

CONCLUSIONS

This validated preoperative prediction model for 1-year mortality identifies patients less likely to benefit from EVAR. Appropriateness of intact AAA EVAR care delivery can be improved by use of this clinical decision aid to determine which high-risk patients have lower probability of mortality within the first postoperative year relative to their predicted annualized rupture risk.

Screening based on risk factors for abdominal aortic aneurysm in the cardiology clinic

BACKGROUND

The risk factors for abdominal aortic aneurysm (AAA) are present in many of the patients that attend our cardiology service. The aim of this study was the evaluation of the prospects of examining the abdominal aorta during our consultations and the relationship of AAA with risk factors and ischemic cardiopathy.

METHODS

A descriptive transversal observational study was designed including 274 male patients aged ≥60 years, attended consecutively in the cardiology service, in which we studied the abdominal aorta and adjusted a logistic regression model to determine the risk factors associated with AAA.

RESULTS

We were able to visualize and measure the abdominal aorta in 95.4% of cases in a fast and reliable way. The prevalence of AAA was 8.76%. 75% of patients with AAA presented ischemic heart disease. Patients with AAA were characterized by the presence of ischemic cardiopathy (Odds Ratio (OR): 4.27, 95% Confidence Interval (CI): 1.37-13.31, p = 0.012), dyslipidemia (OR: 4.99, 95% CI: 1, 07-23.31; p = 0.041), arterial hypertension (OR: 4.14, 95% CI: 1.07-15.98, p = 0.039), and a longer history of smoking (OR: 1.03; 95% CI: 1002-1.054; p = 0.037).

CONCLUSIONS

The evaluation of the abdominal aorta during cardiology consultations is feasible with the standard resources. Patients treated in the cardiology service present a high prevalence of AAA. We have adjusted and validated a clinical prediction model based on risk factors that allows the identification, in the cardiology consult, of patients with the highest risk of suffering from AAA.

Pharmacologic Management of Aneurysms

Current management of aortic aneurysms relies exclusively on prophylactic operative repair of larger aneurysms. Great potential exists for successful medical therapy that halts or reduces aneurysm progression and hence alleviates or postpones the need for surgical repair. Preclinical studies in the context of abdominal aortic aneurysm identified hundreds of candidate strategies for stabilization, and data from preoperative clinical intervention studies show that interventions in the pathways of the activated inflammatory and proteolytic cascades in enlarging abdominal aortic aneurysm are feasible. Similarly, the concept of pharmaceutical aorta stabilization in Marfan syndrome is supported by a wealth of promising studies in the murine models of Marfan syndrome-related aortapathy. Although some clinical studies report successful medical stabilization of growing aortic aneurysms and aortic root stabilization in Marfan syndrome, these claims are not consistently confirmed in larger and controlled studies. Consequently, no medical therapy can be recommended for the stabilization of aortic aneurysms. The discrepancy between preclinical successes and clinical trial failures implies shortcomings in the available models of aneurysm disease and perhaps incomplete understanding of the pathological processes involved in later stages of aortic aneurysm progression. Preclinical models more reflective of human pathophysiology, identification of biomarkers to predict severity of disease progression, and improved design of clinical trials may more rapidly advance the opportunities in this important field.

Pentagalloyl Glucose and Its Functional Role in Vascular Health: Biomechanics and Drug-Delivery Characteristics

Pentagalloyl glucose (PGG) is an elastin-stabilizing polyphenolic compound that has significant biomedical benefits, such as being a free radical sink, an anti-inflammatory agent, anti-diabetic agent, enzymatic resistant properties, etc. This review article focuses on the important benefits of PGG on vascular health, including its role in tissue mechanics, the different modes of pharmacological administration (e.g., oral, intravenous and endovascular route, intraperitoneal route, subcutaneous route, and nanoparticle based delivery and microbubble-based delivery), and its potential therapeutic role in vascular diseases such as abdominal aortic aneurysms (AAA). In particular, the use of PGG for AAA suppression and prevention has been demonstrated to be effective only in the calcium chloride rat AAA model. Therefore, in this critical review we address the challenges that lie ahead for the clinical translation of PGG as an AAA growth suppressor.

A study of outcomes in conservatively managed patients with large abdominal aortic aneurysms deemed unfit for surgical repair

BACKGROUND

The current advancement and increasing use of diagnostic imaging has led to increased detection of abdominal aortic aneurysms (AAA). Many of these patients are unfit for elective AAA surgery.

AIM

To investigate the outcome of conservative management of unfit patients with large AAA (>5.5 cm) who are turned down for elective surgical intervention.

PATIENTS AND METHODS

Between January 2006 and April 2017, 457 patients presented with AAA >5.5 cm. Seventy-six patients (M: F 54:22) were deemed unfit for elective repair. Mean age was 79.8 years (range 64-96). Mean AAA size was 60.22 mm (55-83).

RESULTS

Forty-nine of the 76 patients (64%) had died by April 2017. Fifteen (19.7%) patients died directly because of their aneurysm rupture. A further 34 (44.7%) patients died from non-aneurysm-related causes.

CONCLUSION

Patients with large AAA deemed unfit for elective surgery have an overall poor prognosis and die mainly from other causes than AAA. Surgical intervention when rupture occurs results in poor survival.

Manufacturing Abdominal Aorta Hydrogel Tissue-Mimicking Phantoms for Ultrasound Elastography Validation

Ultrasound (US) elastography, or elasticity imaging, is an adjunct imaging technique that utilizes sequential US images of soft tissues to measure the tissue motion and infer or quantify the underlying biomechanical characteristics. For abdominal aortic aneurysms (AAA), biomechanical properties such as changes in the tissue's elastic modulus and estimates of the tissue stress may be essential for assessing the need for the surgical intervention. Abdominal aortic aneurysms US elastography could be a useful tool to monitor AAA progression and identify changes in biomechanical properties characteristic of high-risk patients. A preliminary goal in the development of an AAA US elastography technique is the validation of the method using a physically relevant model with known material properties. Here we present a process for the production of AAA tissue-mimicking phantoms with physically relevant geometries and spatially modulated material properties. These tissue phantoms aim to mimic the US properties, material modulus, and geometry of the abdominal aortic aneurysms. Tissue phantoms are made using a polyvinyl alcohol cryogel (PVA-c) and molded using 3D printed parts created using computer aided design (CAD) software. The modulus of the phantoms is controlled by altering the concentration of PVA-c and by changing the number of freeze-thaw cycles used to polymerize the cryogel. The AAA phantoms are connected to a hemodynamic pump, designed to deform the phantoms with the physiologic cyclic pressure and flows. Ultra sound image sequences of the deforming phantoms allowed for the spatial calculation of the pressure normalized strain and the identification of mechanical properties of the vessel wall. Representative results of the pressure normalized strain are presented.

Ultrasound screening for abdominal aortic aneurysm: current practice, challenges and controversies

The UK screening programme began in 2009, and has now been expanded around the UK. Long-term follow-up of the original cohorts continues to demonstrate significant benefits for abdominal aortic aneurysm (AAA)-related and all-cause mortality , and results from the first 5 years of the formal screening programme have demonstrated similar success. Ultrasound scanning is an effective and safe screening tool for the detection of AAA, although a variety of measurement protocols are employed internationally. Key challenges for the future of the programme relate to declining incidence of screen detected aneurysms.  Recent publications have demonstrated a UK incidence of only 1.34%, compared to 4.9-7.2% of men invited for screening in the original trials. Work into increasing engagement amongst the target group, and expanding screening to siblings and women is underway to address this issue. This review describes the evidence behind the screening programme, its justification in addressing AAA as a significant health problem and discusses some of the potential developments in the future.

Detecting Regional Stiffness Changes in Aortic Aneurysmal Geometries Using Pressure-Normalized Strain

Transabdominal ultrasound elasticity imaging could improve the assessment of rupture risk for abdominal aortic aneurysms by providing information on the mechanical properties and stress or strain states of vessel walls. We implemented a non-rigid image registration method to visualize the pressure-normalized strain within vascular tissues and adapted it to measure total strain over an entire cardiac cycle. We validated the algorithm's performance with both simulated ultrasound images with known principal strains and anatomically accurate heterogeneous polyvinyl alcohol cryogel vessel phantoms. Patient images of abdominal aortic aneurysm were also used to illustrate the clinical feasibility of our imaging algorithm and the potential value of pressure-normalized strain as a clinical metric. Our results indicated that pressure-normalized strain could be used to identify spatial variations in vessel tissue stiffness. The results of this investigation were sufficiently encouraging to warrant a clinical study measuring abdominal aortic pressure-normalized strain in a patient population with aneurysmal disease.

A primer on infrarenal abdominal aortic aneurysms

Ruptured abdominal aortic aneurysms have an alarmingly high mortality rate that often exceeds 50%, even when patients survive long enough to be transported to hospitals. Historical data have shown that ruptures are especially likely to occur with aneurysms measuring ≥6 cm in diameter, but there are so many exceptions to this that several randomized clinical trials have been done in an attempt to determine whether smaller aneurysms should be repaired electively as soon as they are discovered. More recently, further trials have been conducted in order to compare the relative benefits and disadvantages of modern endovascular aneurysm repair to those of traditional open surgery. This review summarizes current evidence from randomized trials and large population-based datasets regarding two questions that are uppermost in the mind of virtually every patient who is found to have an abdominal aortic aneurysm. Should it be fixed? What are the risks?

Experiences of the screening process and the diagnosis abdominal aortic aneurysm among 65-year-old men from invitation to a 1-year surveillance

The prevalence of abdominal aortic aneurysm (AAA) is reported to be 2.2%-8% among men >65 years. During recent years, screening programs have been developed to detect AAA, prevent ruptures, and thereby saving lives. Therefore, most men with the diagnosis are monitored conservatively with regular reviews. The objective of the study was to describe how men diagnosed with abdominal aortic aneurysm <55 mm discovered by screening experience the process and diagnosis from invitation to 1 year after screening. A total of eleven 65-year-old men were included in three focus groups performed in a University Hospital in Sweden. These were qualitatively analyzed using manifest and latent content analysis. The experience of the screening process and having an abdominal aortic aneurysm in a long-term perspective revealed three categories: "trusting the health care system," emphasizing the need for continual follow-ups to ensure feelings of security; "the importance size," meaning that the measure was abstract and hard to understand; and "coping with the knowledge of abdominal aortic aneurysm," denoting how everyday life was based mostly on beliefs, since a majority lacked understanding about the meaning of the condition. The men want regular surveillance and surrendered to the health care system, but simultaneously experienced a lack of support thereof. Knowing the size of the aorta was important. The men expressed insecurity about how lifestyle might influence the abdominal aortic aneurysm and what they could do to improve their health condition. This highlights the importance of communicating knowledge about the abdominal aortic aneurysm to promote men's feelings of security and giving space to discuss the size of the aneurysm and lifestyle changes.

Application of Metabolic Profiling to Abdominal Aortic Aneurysm Research

Abdominal aortic aneurysm (AAA) is a complex disease posing diagnostic and therapeutic challenges. Metabonomics may aid in the diagnosis of AAA, determination of individualized risk, discovery of therapeutic targets, and improve understanding of pathogenesis. A systematic review of the diversity and outcomes of existing AAA metabonomic research has been performed. Original research studies applying metabonomics to human aneurysmal disease are included. Seven relevant articles were identified: four studies were based on plasma/serum metabolite profiling, and three studies examined aneurysmal tissue. Aminomalonic acid, guanidinosuccinic acid, and glycerol emerge as potential plasma biomarkers of large aneurysm. Lipid profiling improves predictive models of aneurysm presence. Patterns of metabolite variation associated with AAA relate to carbohydrate and lipid metabolism. Perioperative perturbations in metabolites suggest differential systemic inflammatory responses to surgery, generating hypotheses for adjunctive perioperative therapy. Significant limitations include small study sizes, lack of correction for multiple testing false discovery rates, and single time-point sampling. Metabolic profiling carries the potential to identify biomarkers of AAA and elucidate pathways underlying aneurysmal disease. Statistically and methodologically robust studies are required for validation, addressing the hiatus in understanding mechanisms of aneurysm growth and developing effective treatment strategies.

Extended use of endovascular aneurysm sealing for ruptured abdominal aortic aneurysms

Endovascular repair of abdominal aortic aneurysms (EVAR) is now an established treatment modality for suitable patients presenting with aneurysm rupture. EVAR for ruptured aneurysms reduces transfusion, mechanical ventilation, intensive care. and hospital stay when compared with open surgery. In the emergency setting, however, EVAR is limited by low applicability due to adverse clinical or anatomical characteristics and increased need for reintervention. In addition, ongoing bleeding from aortic side branches post-EVAR can cause hemodynamic instability, larger hematomas, and abdominal compartment syndrome. Endovascular aneurysm sealing, based on polymer filling of the aneurysm, has the potential to overcome some of the limitations of EVAR for ruptured aneurysms and to improve outcomes. Recent literature suggests that endovascular aneurysm sealing can be performed with early mortality similar to that of EVAR for ruptured aortic aneurysms, but experience is limited to a few centers and a small number of patients. The addition of chimney grafts can increase the applicability of endovascular aneurysm sealing in order to treat short-neck and juxtarenal aneurysms as an alternative to fenestrated endografts. Further evaluation of the technique, with larger longitudinal studies, is necessary before advocating wider implementation of endovascular aneurysm sealing in the emergency setting.

The Concept of Risk Assessment and Being Unfit for Surgery

The concept of risk assessment and the identification of surgical unfitness for vascular intervention is a particularly controversial issue today as the minimally invasive surgical population has increased not only in volume but also in complexity (comorbidity profile) and age, requiring an improved pre-operative selection and definition of high risk. A practical step by step (three steps, two points for each) approach for surgical risk assessment is suggested in this review. As a general rule, the identification of a "high risk" patient for vascular surgery follows a step by step process where the risk is clearly defined, quantified (when too "high"?), and thereby stratified based on the procedure, the patient, and the hospital, with the aid of predictive risk scores. However, there is no standardized, updated, and objective definition for surgical unfitness today. The major gap in the current literature on the definition of high risk in vascular patients explains the lack of sound validated predictive systems and limited generalizability of risk scores in vascular surgery. In addition, the concept of fitness is an evolving tool and many traditional high risk criteria and definitions are no longer valid. Given the preventive purpose of most vascular procedures performed in elderly asymptomatic patients, the decision to pursue or withhold surgery requires realistic estimates not only regarding individual peri-operative mortality, but also life expectancy, healthcare priorities, and the patient's primary goals, such as prolongation of life versus maintenance of independence or symptom relief. The overall "frailty" and geriatric risk burden, such as cognitive, functional, social, and nutritional status, are variables that should be also included in the analyses for stratification of surgical risk in elderly vascular patients.

Cost-effectiveness of Screening for Abdominal Aortic Aneurysm in Combination with Medical Intervention in Patients with Small Aneurysms

OBJECTIVES

Screening for abdominal aortic aneurysm (AAA) among 65 year old men has been proven cost-effective, but nowadays is conducted partly under new conditions. The prevalence of AAA has decreased, and endovascular aneurysm repair (EVAR) has become the predominant surgical method for AAA repair in many centers. At the Malmö Vascular Center pharmacological secondary prevention with statins, antiplatelet therapy, and blood pressure reduction is initiated and given to all patients with AAA. This study evaluates the cost-effectiveness of AAA screening under the above mentioned conditions.

METHODS

This was a Markov cohort simulation. A total of 4,300 65 year old men were invited to annual AAA screening; the attendance rate was 78.3% and AAA prevalence was 1.8%. A Markov model with 11 health states was used to evaluate cost-effectiveness of AAA screening. Background data on rupture risks, costs, and effectiveness of surgical interventions were obtained from the participating unit, the national Swedvasc Registry, and from the scientific literature.

RESULTS

The additional costs of the screening strategy compared with no screening were €169 per person and year. The incremental health gain per subject in the screened cohort was 0.011 additional quality adjusted life years (QALYs), corresponding to an incremental cost-effectiveness ratio (ICER) of €15710 per QALY. Assuming a 10% reduction of all cause mortality, the incremental cost of screening was €175 per person and year. The gain per subject in the screened cohort was 0.013 additional QALYs, corresponding to an ICER of €13922 per QALY CONCLUSIONS: AAA screening remains cost-effective according to both the Swedish recommendations and the UK National Institute for Health and Care Excellence recommendations in the new era of lower AAA prevalence, EVAR as the predominant surgical method, and secondary prevention for all AAA patients.