Current issues in the treatment of women with abdominal aortic aneurysm

Sex differences in outcomes among adults undergoing abdominal aortic aneurysm repair

OBJECTIVE

Although the differences in short-term outcomes between male and female patients in abdominal aortic aneurysm (AAA) repair have been well studied, it remains unclear if these sex disparities extend to other long-term adverse outcomes after AAA repair, such as reintervention and late rupture.

METHODS

We performed a retrospective cohort study of 13,007 patients who underwent either endovascular (EVAR) or open AAA repair (OAR) between 2003 and 2015 using data from the Vascular Quality Initiative registries. Eligible patients were linked to fee-for-service Medicare claims to identify late outcomes of rupture and aneurysm-specific reintervention.

RESULTS

The mean age of our cohort was 76 ± 6.7 years, 22% were female, 94% were White, and 77% underwent EVAR. The 10-year rupture incidence was slightly higher for women at 4.8 per 1000 person-years, vs 3.9 for men, but this difference was not statistically significant after risk adjustment (hazard ratio [HR] = 1.13, 95% confidence interval [CI]: 0.74-1.73). Likewise, we found no sex difference in reintervention rates (5.1 vs 4.8 in women per 1000 person-years) even after risk adjustment (HR = 0.95, 95% CI: 0.83-1.09). Regression models suggest effect modification by repair type for reintervention, where women who underwent index EVAR had a higher risk of reintervention than men (HR = 1.08, 95% CI: 0.93-1.26), whereas women who underwent OAR were at a lower risk of reintervention than men (HR = 0.79, 95% CI: 0.58-1.08); however, neither effect reached statistical significance within each subgroup. In addition, we found that the risk of reintervention for women vs men varied by clinical presentation, where women were less likely to undergo reintervention after an elective or symptomatic AAA repair but were more likely to undergo reintervention after a repair for AAA rupture (HR = 1.70, 95% CI: 1.05-2.75).

CONCLUSIONS

Male and female patients who underwent AAA repair had similar rates of reintervention and late aneurysm rupture in the 10 years after their procedure. However, our findings suggest that repair type and clinical presentation may affect the role of sex in clinical outcomes and warrant further exploration in these subgroups.

Elective Endovascular vs Open Repair for Elective Abdominal Aortic Aneurysm in Patients ≥80 years of Age: A Systematic Review and Meta-Analysis

OBJECTIVE

To provide updated, pooled evidence on clinical outcomes among octogenarians (aged ≥80 years) with abdominal aortic aneurysm (AAA) managed by elective endovascular repair, compared to conventional open repair.

METHODS

PubMed, Embase, and Scopus databases were systematically searched. Studies that were either observational or randomized controlled trials were considered for the review. Included studies were conducted in elderly subjects (≥80 years) with AAA, and clinical and mortality outcomes were compared between endovascular and open surgical repair. Those reporting on outcomes of patients with urgent repair were excluded. The primary outcomes of interest were mortality and risk of complications. The pooled effect sizes were reported as odds ratio (OR) for categorical outcomes and weighted mean difference (WMD) for continuous outcomes. STATA software was used for statistical analysis.

RESULTS

The meta-analysis included 15 studies. Compared to those undergoing open repair, patients receiving endovascular repair had significantly reduced risk of immediate post-operative mortality (OR .23, 95% CI: .20, .27), overall complication (OR .30, 95% CI: .20, .44), cardiac (OR .23, 95% CI: .16, .35), renal (OR .29, 95% CI: .18, .46), pulmonary (OR .14, 95% CI: .09, .21) and bleeding related (OR .59, 95% CI: .42, .83) complications. The risk of mortality at latest follow up (at 36 months and 60 months) was similar in the two groups. The total blood loss (ml) (WMD -1126.47, 95% CI: -1497.81, -755.13), operative time (min) (WMD -29.40, 95% CI: -56.19, -2.62), length of intensive care unit stay (days) (WMD -2.27, 95% CI: -3.43, -2.12) and overall hospital stay (days) (WMD -6.64, 95% CI: -7.60, -5.68) was significantly lower in those undergoing endovascular repair.

CONCLUSIONS

Endovascular repair appears to be better than open repair of AAA in this high-risk, frail population, with respect to short term outcomes. The benefits of reduced risk of short term mortality, complications, and better peri and post-operative outcomes may be considered when making a choice between these two surgical approaches. Randomized controlled trials are needed to provide reliable evidence on the effect of EVAR on long term survival.

Abdominal Aortic Thrombus Segmentation in Postoperative Computed Tomography Angiography Images Using Bi-Directional Convolutional Long Short-Term Memory Architecture

Abdominal aortic aneurysm (AAA) is a fatal clinical condition with high mortality. Computed tomography angiography (CTA) imaging is the preferred minimally invasive modality for the long-term postoperative observation of AAA. Accurate segmentation of the thrombus region of interest (ROI) in a postoperative CTA image volume is essential for quantitative assessment and rapid clinical decision making by clinicians. Few investigators have proposed the adoption of convolutional neural networks (CNN). Although these methods demonstrated the potential of CNN architectures by automating the thrombus ROI segmentation, the segmentation performance can be further improved. The existing methods performed the segmentation process independently per 2D image and were incapable of using adjacent images, which could be useful for the robust segmentation of thrombus ROIs. In this work, we propose a thrombus ROI segmentation method to utilize not only the spatial features of a target image, but also the volumetric coherence available from adjacent images. We newly adopted a recurrent neural network, bi-directional convolutional long short-term memory (Bi-CLSTM) architecture, which can learn coherence between a sequence of data. This coherence learning capability can be useful for challenging situations, for example, when the target image exhibits inherent postoperative artifacts and noises, the inclusion of adjacent images would facilitate learning more robust features for thrombus ROI segmentation. We demonstrate the segmentation capability of our Bi-CLSTM-based method with a comparison of the existing 2D-based thrombus ROI segmentation counterpart as well as other established 2D- and 3D-based alternatives. Our comparison is based on a large-scale clinical dataset of 60 patient studies (i.e., 60 CTA image volumes). The results suggest the superior segmentation performance of our Bi-CLSTM-based method by achieving the highest scores of the evaluation metrics, e.g., our Bi-CLSTM results were 0.0331 higher on total overlap and 0.0331 lower on false negative when compared to 2D U-net++ as the second-best.

A New Method for Quantifying Abdominal Aortic Wall Shear Stress Using Phase Contrast Magnetic Resonance Imaging and the Womersley Solution

Wall shear stress (WSS) is an important mediator of cardiovascular pathologies and there is a need for its reliable evaluation as a potential prognostic indicator. The purpose of this work was to develop a method that quantifies WSS from two-dimensional (2D) phase contrast magnetic resonance (PCMR) imaging derived flow waveforms, apply this method to PCMR data acquired in the abdominal aorta of healthy volunteers, and to compare PCMR-derived WSS values to values predicted from a computational fluid dynamics (CFD) simulation. The method uses PCMR-derived flow versus time waveforms constrained by the Womersley solution for pulsatile flow in a cylindrical tube. The method was evaluated for sensitivity to input parameters, intrastudy repeatability and was compared with results from a patient-specific CFD simulation. 2D-PCMR data were acquired in the aortas of healthy men (n = 12) and women (n = 15) and time-averaged WSS (TAWSS) was compared. Agreement was observed when comparing TAWSS between CFD and the PCMR flow-based method with a correlation coefficient of 0.88 (CFD: 15.0 ± 1.9 versus MRI: 13.5 ± 2.4 dyn/cm2) though comparison of WSS values between the PCMR-based method and CFD predictions indicate that the PCMR method underestimated instantaneous WSS by 3.7 ± 7.6 dyn/cm2. We found no significant difference in TAWSS magnitude between the sexes; 8.19 ± 2.25 versus 8.07 ± 1.71 dyn/cm2, p = 0.16 for men and women, respectively.

The Effect of Smoking Status on Perioperative Morbidity and Mortality after Open and Endovascular Abdominal Aortic Aneurysm Repair

OBJECTIVES

This study quantifies the extent to which active tobacco smoking is deleterious towards outcomes following open and endovascular AAA repair.

METHODS

Open and endovascular abdominal aortic aneurysm (AAA) repairs between January 2003 and June 2020 in the Vascular Quality Initiative (VQI) were queried. Rupture, symptomatic status, and lack of 90 day follow up were exclusions. Patients were then placed into one of six groups : open AAA with active smoking (n=3788); open AAA with prior smoking (n=4614); open AAA never smokers (817); endovascular AAA active smokers (n=14173); endovascular AAA former smokers (n=25,831); and, endovascular AAA never smokers (n=6064). Comparison of baseline characteristics, co-morbidities, and adverse outcomes across each of the 6 cohorts was performed with open AAA in active smokers serving as the reference. Sub-analysis investigating open AAA repair in active smokers relative to open AAA in patients confirmed in VQI to have quit smoking between 30 and 90 days before surgery was performed. Smoking cessation for a minimum of 30 days before surgery was required to fall into the former smoker category.

RESULTS

In comparing open AAA in active smokers to open AAA in former and never smokers, the active smokers experienced significantly higher rates of pneumonia (P<.001). Combined additive morbidity and mortality was highest (54%) in active smokers (P<.001 relative to all cohorts other than open AAA former smokers P=.21). Smoking status did not impact morbidity or mortality incidence across individuals undergoing EVAR. Binary logistic regression for all AAA patients (open and endovascular combined) revealed those with any history of smoking to be more likely to experience 90 day mortality (adjusted OR 2.5 (2.2-2.9), P<.001) relative to never-smokers. Active smokers were similarly more likely to experience 90 day mortality than prior/never smokers combined (OR 1.23 (1.07-1.38), P<.001). Mortality within 90 days was significantly more likely (P<.001) with aging, female gender, larger aneurysms, preoperative history of congestive heart failure, chronic obstructive pulmonary disease, chronic renal insufficiency, peripheral artery disease, body mass index under 20 and over 35 mg/kg². Diabetes and coronary artery disease were also associated with 90 day mortality (P= .045 and .049 respectively). Quitting smoking between 30 and 90 days before open repair reduced combined additive morbidity and mortality relative to active smokers (OR 1.34, P =.038).

CONCLUSIONS

Smoking cessation 30 days before open AAA repair reduces perioperative morbidity and mortality. Smoking status does not impact morbidity and mortality in patients undergoing endovascular AAA repair. When combining all patients (open and endovascular), higher rates of 90 day mortality are associated with any history of smoking, aging, female gender and advanced pre-existing co-morbidities on multivariable analysis.

Automatic Detection and Segmentation of Thrombi in Abdominal Aortic Aneurysms Using a Mask Region-Based Convolutional Neural Network with Optimized Loss Functions

The detection and segmentation of thrombi are essential for monitoring the disease progression of abdominal aortic aneurysms (AAAs) and for patient care and management. As they have inherent capabilities to learn complex features, deep convolutional neural networks (CNNs) have been recently introduced to improve thrombus detection and segmentation. However, investigations into the use of CNN methods is in the early stages and most of the existing methods are heavily concerned with the segmentation of thrombi, which only works after they have been detected. In this work, we propose a fully automated method for the whole process of the detection and segmentation of thrombi, which is based on a well-established mask region-based convolutional neural network (Mask R-CNN) framework that we improve with optimized loss functions. The combined use of complete intersection over union (CIoU) and smooth L1 loss was designed for accurate thrombus detection and then thrombus segmentation was improved with a modified focal loss. We evaluated our method against 60 clinically approved patient studies (i.e., computed tomography angiography (CTA) image volume data) by conducting 4-fold cross-validation. The results of comparisons to multiple other state-of-the-art methods suggested the superior performance of our method, which achieved the highest F1 score for thrombus detection (0.9197) and outperformed most metrics for thrombus segmentation.

Sex Differences in Outcomes Following Ruptured Abdominal Aortic Aneurysm Repair

IMPORTANCE

Sex differences in aortic surgery outcomes are commonly reported. However, data on ruptured abdominal aortic aneurysm (rAAA) repair outcomes in women vs men are limited.

OBJECTIVE

To assess differences in perioperative and long-term mortality following rAAA repair in women vs men.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter, retrospective cohort study was conducted using the Vascular Quality Initiative database, which prospectively captures information on patients who undergo vascular surgery across 796 academic and community hospitals in North America. All patients who underwent endovascular or open rAAA repair between January 1, 2003, and December 31, 2019, were included. Outcomes were assessed up to January 1, 2020.

EXPOSURES

Patient sex.

MAIN OUTCOMES AND MEASURES

Demographic, clinical, and procedural characteristics were recorded, and differences between women vs men were assessed using independent t test and χ2 test. The primary outcomes were in-hospital and 8-year mortality. Associations between sex and outcomes were analyzed using univariable and multivariable logistic regression and Cox proportional hazards regression analysis.

RESULTS

A total of 1160 (21.9%) women and 4148 (78.1%) men underwent rAAA repair during the study period. There was a similar proportion of endovascular repairs in women and men (654 [56.4%] vs 2386 [57.5%]). Women were older (mean [SD] age, 75.8 [9.3] vs 71.7 [9.6] years), more likely to have chronic kidney disease (718 [61.9%] vs 2184 [52.7%]), and presented with ruptured aneurysms of smaller diameters (mean [SD] 68 [18.2] vs 78 [30.2] mm). In-hospital mortality was higher in women (34.4% vs 26.6%; odds ratio, 1.44; 95% CI, 1.25-1.66), which persisted after adjusting for demographic, clinical, and procedural characteristics (adjusted odds ratio, 1.36; 95% CI, 1.12-1.66; P = .002). Eight-year survival was lower in women (36.7% vs 49.5%; hazard ratio, 1.25; 95% CI, 1.04-1.50; P = .02), which persisted when stratified by endovascular and open repair. This survival difference existed in both the US and Canada. Variables associated with long-term mortality in women included older age and chronic kidney disease.

CONCLUSIONS AND RELEVANCE

Women who underwent rAAA repair had higher perioperative and 8-year mortality rates following both endovascular and open repair compared with men. Older age and higher rates of chronic kidney disease in women were associated with higher mortality rates. These findings suggest that future studies should assess the reasons for these disparities and whether opportunities exist to improve AAA care for women.

A Sinister Gut Feeling

Women are generally spared from abdominal aortic aneurysm (AAA) formation by the immunomodulating effects of estrogen. However, once they develop it, especially in the postmenopausal group, its behavior is more sinister with rapid expansion, a higher tendency to rupture, and higher mortality as compared to the male counterparts. Reported here is a case of AAA in a postmenopausal woman who came to the outpatient department with low backache, vague abdominal pain, and dysuria which initially gave a picture of pelvic inflammation with urinary tract infection but was later found out to be aortic aneurysm.

A Predictive Analysis of Wall Stress in Abdominal Aortic Aneurysms Using a Neural Network Model

Rupture risk assessment of abdominal aortic aneurysms (AAAs) by means of quantifying wall stress is a common biomechanical strategy. However, the clinical translation of this approach has been greatly limited due to the complexity associated with the computational tools required for its implementation. Thus, being able to estimate wall stress using nonbiomechanical markers that can be quantified as a direct outcome of clinical image segmentation would be advantageous in improving the potential implementation of said strategy. In the present work, we investigated the use of geometric indices to predict patient-specific AAA wall stress by means of a novel neural network (NN) modeling approach. We conducted a retrospective review of existing clinical images of two patient groups: 98 asymptomatic and 50 symptomatic AAAs. The images were subject to a protocol consisting of image segmentation, processing, volume meshing, finite element modeling, and geometry quantification, from which 53 geometric indices and the spatially averaged wall stress (SAWS) were calculated. SAWS estimated from finite element analysis was considered the gold standard for the predictions. We developed feed-forward NN models composed of an input layer, two dense layers, and an output layer using Keras, a deep learning library in python. The NN models were trained, tested, and validated independently for both AAA groups using all geometric indices, as well as a reduced set of indices resulting from a variable reduction procedure. We compared the performance of the NN models with two standard machine learning algorithms (MARS: multivariate adaptive regression splines and GAM: generalized additive model) and a linear regression model (GLM: generalized linear model). With the reduced sets of indices, the NN-based approach exhibited the highest mean goodness-of-fit (for the symptomatic group 0.71 and for the asymptomatic group 0.79) and lowest mean relative error (17% for both groups). In contrast, MARS yielded a mean goodness-of-fit of 0.59 for the symptomatic group and 0.77 for the asymptomatic group, with relative errors of 17% for the symptomatic group and 22% for the asymptomatic group. GAM had a mean goodness-of-fit of 0.70 for the symptomatic group and 0.80 for the asymptomatic group, with relative errors of 16% for the symptomatic group and 20% for the asymptomatic group. GLM did not perform as well as the other algorithms, with a mean goodness-of-fit of 0.53 for the symptomatic group and 0.70 for the asymptomatic group, with relative errors of 19% for the symptomatic group and 23% for the asymptomatic group. Nevertheless, the NN models required a reduced set of 15 and 13 geometric indices to predict SAWS for the symptomatic and asymptomatic AAA groups, respectively. This was in contrast to the reduced set of nine and eight geometric indices required to predict SAWS with the MARS and GAM algorithms for each AAA group, respectively. The use of NN modeling represents a promising alternative methodology for the estimation of AAA wall stress using geometric indices as surrogates, in lieu of finite element modeling. The performance metrics of NN models are expected to improve with significantly larger group sizes, given the suitability of NN modeling for "big data" applications.

Female sex is associated with comparable 5-year outcomes after contemporary endovascular aneurysm repair despite more challenging anatomy

BACKGROUND

Women with abdominal aortic aneurysms less often meet anatomic criteria for endovascular repair and experience worse perioperative and long-term survival.

METHODS

We compared long-term survival, aneurysm-related mortality, and rates of endoleaks and reinterventions between male and female patients in the Endurant Stent Graft Natural Selection Global Postmarket Registry (ENGAGE) using 2:1 propensity score matching.

RESULTS

There were 1130 male patients and 133 female patients, yielding 399 patients after matching (266 male patients, 133 female patients). Female patients were older, with smaller aneurysms, smaller iliac arteries, and shorter, more angulated necks, and they were more often treated outside the device instructions for use (all P < .001). Through 5 years, female patients experienced overall mortality comparable to that of well-matched male patients (34% vs 38%, respectively; hazard ratio, 0.89 [0.61-1.29]; P = .54) and lower aneurysm-related mortality (0% vs 3%; P = .047). Female patients experienced higher rates of any postoperative type IA endoleak through 5 years (10% vs 1%; P < .001) but comparable rates of secondary endovascular procedures (14% vs 16%; P = .40). Female sex was independently associated with significantly higher risk of long-term type IA endoleaks (hazard ratio, 4.8 [1.2-20.8]; P = .04), even after accounting for anatomic factors. No female patient experienced aneurysm rupture during follow-up, and only one female patient underwent conversion to open repair.

CONCLUSIONS

Despite more challenging anatomy, female patients in the ENGAGE registry had long-term outcomes comparable to those of male patients. However, female patients experienced higher rates of type IA endoleaks. Although standard endovascular aneurysm repair remains a viable solution for most women, whether high-risk patients may be better served with open surgery, custom-made devices, EndoAnchors (Aptus Endosystems, Sunnyvale, Calif), or chimneys is worthy of further study.

Association of Sex With Repair Type and Long-term Mortality in Adults With Abdominal Aortic Aneurysm

IMPORTANCE

Sex-based differences exist in the prevalence and clinical presentation of abdominal aortic aneurysm (AAA). However, it is unclear if sex is associated with AAA repair type and long-term mortality.

OBJECTIVE

To investigate whether a sex-related difference exists in mortality risk after AAA repair owing to differences in repair type.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study uses data from the Vascular Quality Initiative, a national clinical registry, and Medicare claims to investigate endovascular and surgical repair procedures performed between January 1, 2003, and September 30, 2015, in patients aged 65 years or older with AAA. The data were analyzed from October 1, 2018, to November 19, 2019.

EXPOSURE

Sex of the patient.

MAIN OUTCOMES AND MEASURES

Endovascular (EVR) or open surgical AAA repair type and subsequent long-term, all-cause mortality.

RESULTS

In this cohort study of 16 386 patients, 12 757 (77.9%) were men and 3629 (22.1%) were women. Women were more likely than men to be older (mean [SD] age, 77 [6.5] years vs 75 [6.6] years; P < .001), active smokers (33% vs 28%; P < .001), and to have smaller aneurysms (mean [SD] diameter, 57 [11.7] mm vs 59 [17.7] mm; P < .001). Surgical AAA repair was performed in 27% (983 of 3629) of women compared with 18% (2328 of 12 757) of men (P < .001). After inverse probability weighting for risk adjustment, women were more likely to receive open surgical repair than EVR repair (risk ratio, 1.65; 95% CI, 1.51-1.80). The 10-year unadjusted survival rate after EVR repair was 14% lower in women than in men (23% vs 37%; log-rank P < .001), but the rates were comparable after open surgical repair (36% in men vs 32% in women; log-rank P = .22). Risk-adjusted analysis showed that women were associated with higher mortality rates after EVR repair (hazard ratio, 1.13; 95% CI, 1.03-1.24), whereas both men and women had a similar risk of death after open surgical repair (hazard ratio, 0.94; 95% CI, 0.84-1.06). After further stratification by symptom severity, higher risk of mortality among women was limited to elective EVR and open surgical repair for ruptured AAA.

CONCLUSIONS AND RELEVANCE

In this study, women were 65% more likely than men to undergo open surgical repair. After EVR repair, women were 13% more likely to die than men, although no sex-based difference in mortality was found after open surgical repair. The differential treatment benefit of EVR repair in women is concerning given the shift toward an EVR-first approach to AAA repair.

Sex differences in repair rates and outcomes of patients with ruptured abdominal aortic aneurysm

BACKGROUND

Data are conflicting on sex differences in ruptured abdominal aortic aneurysm (rAAA) repair rates and outcomes have rarely been addressed. The aim of this study was to investigate differences in the management and outcome of rAAA in men and women, and to describe time trends over a 15-year interval.

METHODS

Data on patients with rAAA were extracted from the Swedish National Patient Registry and the Cause of Death Registry for the interval 2001-2015. The study included patients with rAAA whether or not they were admitted to any hospital in Sweden. A propensity score-matched model was used to determine sex differences in repair type and outcome after rupture. Time trends for rAAA events and mortality were investigated.

RESULTS

Some 10 724 patients were identified. A higher percentage of men were admitted to hospital (79·8 versus 77·5 per cent; P = 0·011). Of those admitted, a higher percentage of men than women were treated (56·6 versus 40·4 per cent, P < 0·001). Women were less likely to be treated when diagnosed with rAAA (average treatment effect (ATE) in the model -0·080, 95 per cent c.i. -0·106 to -0·055; P < 0·001). Thirty-day mortality was also higher in women (ATE 0·094, 0·053 to 0·135; P < 0·001); this effect persisted to 1 year (ATE 0·095, 0·052 to 0·137; P < 0·001). Time trends indicated a decrease in rAAA incidence, mostly owing to a decrease among men.

CONCLUSION

In this study, fewer women with rAAA received surgery and 30-day mortality was higher than in men. There was an overall decrease in rAAA incidence, principally in men.

Endovascular Aneurysm Repair May Provide a Survival Advantage in Patients Deemed Physiologically Ineligible for Open Abdominal Aortic Aneurysm Repair

BACKGROUND

Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity and fitness. It can be used to guide decision making prior to major vascular surgery. The EVAR-2 trial suggested that endovascular aneurysm repair (EVAR) in patients unfit for open repair failed to provide a significant survival advantage over nonsurgical management. The aim of this study is to assess contemporary survival differences between patients with poor CPET measures who underwent EVAR or were not offered surgical intervention.

METHODS

A prospectively maintained database of CPET results of patients considered for elective infrarenal aortic aneurysm repair were interrogated. Anaerobic threshold (AT) of <11 mL/min/kg was used to indicate poor physical fitness. Hospital electronic records were then reviewed for perioperative, reintervention, and long-term outcomes.

RESULTS

Between November 2007 and October 2017, 532 aortic aneurysm repairs were undertaken, of which 376 underwent preoperative CPET. Seventy patients were identified as having an AT <11 mL/min/kg. Thirty-seven patients underwent EVAR and 33 were managed nonsurgically. All-cause survival at 1, 3, and 5 years for those patients who underwent EVAR was 97%, 92%, and 81%, respectively. For those not offered surgical intervention survival at the same points was 72%, 48%, and 24% [hazard ratio, HR = 5.13 (1.67-15.82), P = 0.004]. Aneurysm-specific survival at 1, 3, and 5 years for those patients who underwent EVAR was 97%, 94%, and 94%, respectively. Survival at the same time points for those not offered surgical intervention was 90%, 69%, and 39%, respectively [HR = 7.48 (1.37-40.82), P = 0.02].

CONCLUSIONS

In this small, retrospective, single-center, nonrandomized cohort, EVAR may provide a survival advantage in patients with poor physical fitness identified via CPET. Randomized studies with current generation EVAR are required to validate the results shown here.

Sex differences in national rates of repair of emergency abdominal aortic aneurysm

BACKGROUND

The aim of this study was to assess the sex differences in both the rate and type of repair for emergency abdominal aortic aneurysm (AAA) in England.

METHODS

Hospital Episode Statistics (HES) data sets from April 2002 to February 2015 were obtained. Clinical and administrative codes were used to identify patients who underwent primary emergency definitive repair of ruptured or intact AAA, and patients with a diagnosis of AAA who died in hospital without repair. These three groups included all patients with a primary AAA who presented as an emergency. Sex differences between repair rates and type of surgery (endovascular aneurysm repair (EVAR) versus open repair) over time were examined.

RESULTS

In total, 15 717 patients (83·3 per cent men) received emergency surgical intervention for ruptured AAA and 10 276 (81·2 per cent men) for intact AAA; 12 767 (62·0 per cent men) died in hospital without attempted repair. The unadjusted odds ratio for no repair in women versus men was 2·88 (95 per cent c.i. 2·75 to 3·02). Women undergoing repair of ruptured AAA were older and had a higher in-hospital mortality rate (50·0 versus 41·0 per cent for open repair; 30·9 versus 23·5 per cent for EVAR). After adjustment for age, deprivation and co-morbidities, the odds ratio for no repair in women versus men was 1·34 (1·28 to 1·40). The in-hospital mortality rate after emergency repair of an intact AAA was also higher among women.

CONCLUSION

Women who present as an emergency with an AAA are less likely to undergo repair than men. Although some of this can be explained by differences in age and co-morbidities, the differences persist after case-mix adjustment.

Demonstration of circumferential heterogeneity in displacement and strain in the abdominal aortic wall by spiral cine DENSE MRI

BACKGROUND

Knowledge of tissue properties of the abdominal aorta can improve understanding of vascular disease and guide interventional approaches. Existing MRI methods to quantify aortic wall displacement and strain are unable to discern circumferential heterogeneity.

PURPOSE

To assess regional variation in abdominal aortic wall displacement and strain as a function of circumferential position using spiral cine displacement encoding with stimulated echoes (DENSE).

STUDY TYPE

Prospective.

POPULATION

Cardiovascular disease-free men (n = 8) and women (n = 9) ages 30-42.

SEQUENCES

Prospective electrocardiogram (ECG)-gated and navigator echo-gated spiral, cine 2D DENSE and retrospective ECG-gated phase contrast MR (PCMR) sequences at 3T.

ASSESSMENT

In-plane displacement values of the aortic wall acquired with DENSE were used to determine radial and circumferential aortic wall motion. A quadrilateral-based 2D strain calculation method was implemented to determine strain from the displacement field. Peak displacement and its radial and circumferential contributions as well as peak circumferential strain were compared among eight circumferential wall segments. Distensibility was calculated using PCMR and compared with homogenized circumferential strain.

STATISTICAL TESTS

To account for repeated measurements in volunteers, linear mixed models for mean sector values were created for displacement magnitude, circumferential displacement, radial displacement, and circumferential strain. Comparisons were made between sectors. Calculated distensibility and homogenized circumferential strain were compared using Bland-Altman analysis. Statistical significance was defined as P < 0.05.

RESULTS

Displacement was highest in the anterior wall (1.5 ± 0.7 mm) and was primarily in the radial as compared with circumferential direction (1.04 ± 0.05 mm vs. 0.81 ± 0.42 mm). Circumferential strain was highest in the lateral walls (left 0.16 ± 0.05 and right 0.21 ± 0.12) with homogenized circumferential strain of 0.14 ± 0.05.

DATA CONCLUSION

DENSE imaging in the abdominal aortic wall demonstrated that the anterior aortic wall exhibits the greatest displacement, while the lateral wall experiences the largest circumferential strain.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:731-743.

Influence of Gender on Abdominal Aortic Aneurysm Repair in the Community

BACKGROUND

Women have been shown to experience inferior outcomes following intact and ruptured abdominal aortic aneurysm (AAA) treatment in endovascular aneurysm repair (EVAR) and open surgical repair (OSR) groups. The goal of our study was to compare gender-specific presentation, management, and early outcomes after AAA repair using a statewide registry.

METHODS

We utilized the Washington State's Vascular Interventional Surgical Care and Outcomes Assessment Program registry data collected in 19 hospitals from July 2010 to September 2013. Demographics, presentation, procedural data, and outcomes in elective and emergent AAA repair groups were analyzed.

RESULTS

We identified 1,231 patients (19.6% women) who underwent intact (86.4%) or ruptured AAA (13.6%) repairs. Nine thousand seventy-two (79.0%) patients had EVAR and 259 (21.0%) had OSR. Men and women were of equivalent age and had similar comorbidities, except that women had less coronary artery disease (P < 0.01) and were more likely to suffer from chronic obstructive pulmonary disease (P = 0.05). Women had smaller aneurysm diameters (5.8 ± 1.1 vs. 6.2 ± 1.8 cm, P < 0.01) at the time of presentation and men had slightly higher incidence of rupture at larger aneurysm size. Men were more likely to undergo EVAR, with significant differences in elective (82.1% vs. 74.1%, P = 0.01), but not ruptured repair. Women had significantly higher mortality rates following elective EVAR (3.1% vs. 0.6%, P = 0.01), but not after ruptured or elective open repair. Following elective EVAR, women were less likely to be discharged to home after longer hospital stays (3 vs. 2 days, P < 0.01).

CONCLUSIONS

Despite presentation at a similar age, with a smaller aneurysm diameter, and similar medical comorbidities, women experience substantially worse hospital outcomes primarily driven by elective endovascular procedures. Utilization of endovascular techniques in women still remains lower compared with men. Improvement of elective outcomes in women will likely depend on technical advancements in repair techniques and management strategies that may differ between genders.

Using machine learning methods for predicting inhospital mortality in patients undergoing open repair of abdominal aortic aneurysm

An abdominal aortic aneurysm is an abnormal dilatation of the aortic vessel at abdominal level. This disease presents high rate of mortality and complications causing a decrease in the quality of life and increasing the cost of treatment. To estimate the mortality risk of patients undergoing surgery is complex due to the variables associated. The use of clinical decision support systems based on machine learning could help medical staff to improve the results of surgery and get a better understanding of the disease. In this work, the authors present a predictive system of inhospital mortality in patients who were undergoing to open repair of abdominal aortic aneurysm. Different methods as multilayer perceptron, radial basis function and Bayesian networks are used. Results are measured in terms of accuracy, sensitivity and specificity of the classifiers, achieving an accuracy higher than 95%. The developing of a system based on the algorithms tested can be useful for medical staff in order to make a better planning of care and reducing undesirable surgery results and the cost of the post-surgical treatments.

Gender Differences in Aortic Neck Morphology in Patients with Abdominal Aortic Aneurysms Undergoing Elective Endovascular Aneurysm Repair

BACKGROUND

Previous studies have demonstrated that women tend to have adverse aortic neck morphology leading to exclusion of some women from undergoing endovascular aneurysm repair (EVAR). The objective of this study is to investigate differences in aortic neck morphology in men versus women, changes in the neck morphology and sac behavior after EVAR, and investigate how these features may influence outcomes.

METHODS

We conducted a retrospective review of elective EVARs (2004-2013). We excluded patients who underwent elective EVAR with no postoperative imaging available and those patients with fenestrated repairs. Using TeraRecon and volumetric analysis, several features were investigated. These included percent thrombus, shape, length, angulation of the neck, and changes in neck and abdominal aortic aneurysm diameter.

RESULTS

A total of 146 patients were found to meet inclusion criteria (115 men and 31 women) with similar baseline characteristics. Neck angulation was greater in women (23.9° vs. 13.5°; P < 0.028). The percent thrombus in women was higher than men (35.4% vs. 31%; P < 0.02). Abdominal aneurysm's were smaller in women at 1 year (4.2 cm vs. 5.1 cm; P < 0.002), and secondary interventions were higher in men (11.3% vs. 0%; P < 0.05). Other features such as neck shape, changes in neck diameter, neck length, and percent oversizing of graft where not statistically different between genders.

CONCLUSIONS

Gender differences in neck characteristics and changes in neck morphology do not appear to adversely affect EVAR outcomes. Longer follow-up is necessary to further assess whether these findings are clinically durable.

B lymphocytes in abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a progressive inflammatory disease of the artery walls. Immune cells, including B lymphocytes, are implicated in the pathogenesis of AAA through interconnected mechanisms. Many studies have shown that compared with normal abdominal aortic tissue, the amount of B lymphocytes that infiltrate the adventitia of AAAs was significantly higher. Activated B lymphocytes promote AAA by producing immunoglobulins, cytokines, and matrix metalloproteinases (MMPs), resulting in the activation of macrophages, mast cells (MCs) and complement pathways. Finally, all of these factors lead to the degradation of collagen and matrix proteins and to aortic wall remodeling, which are hallmarks of AAA. However, few studies focus on the relative function of B cells, and their precise mechanisms in AAA remain unclear. Thus, we summarize the current knowledge on the role of B cells in AAA and offer recommendations for further investigation of preventing the progression of AAA.

Evolution of gender-related differences in outcomes from two decades of endovascular aneurysm repair

OBJECTIVE

Women have been under-represented in trials that set guidelines for the management of aortic aneurysms. Several studies reported inferior outcomes in women compared with men after endovascular aneurysm repair (EVAR). We investigated the relationship between gender and outcomes after EVAR.

METHODS

A total of 1380 consecutive patients underwent elective EVAR from 1992 to 2012. Baseline, intraoperative, and postoperative variables by gender were analyzed from a prospective database.

RESULTS

The cohort comprised 214 women (15.5%) and 1166 men (84.5%). Women were older than men at repair (77.8 vs 74.5 years, P < .001) and had less cardiac disease (P = .005). They had shorter (19.8 ± 12.9 vs 26.3 ± 14.7 mm; P < .001) more angulated aortic necks (38.8° ± 16.1° vs 31.2° ± 14.7°; P < .001) and fewer iliac aneurysms (P = .002). Women had more arterial reconstructions (iliac conduits, P = .006; thrombolysis and thrombectomy, P = .013; patch angioplasty, P < .001; endarterectomy, P < .001), more perioperative complications (16.9% vs 9.1%; P = .001), and more in-hospital days (4.1 vs 3.4 days; P = .029). Perioperative mortality was equivalent (women: 2% vs men: 2.3%; P = .73). Mean follow-up was 30.9 months. Women and men experienced equivalent aneurysm-related deaths and overall survival. Survival curve analysis showed endoleaks were more likely to develop in women than men (P = .005); however, there was no difference in rates of arterial reinterventions required for each gender during the follow-up period.

CONCLUSIONS

Female gender is associated with more periprocedural complications, adjunctive arterial procedures, and increased endoleaks but does not affect long-term reinterventions or survival. Further studies are warranted to elucidate the effect of gender on outcomes. These data should be considered when selecting EVAR for men and women.

The association between ASA status and other risk stratification models on postoperative intensive care unit outcomes

BACKGROUND

There is limited medical literature investigating the association between perioperative risk stratification methods and surgical intensive care unit (SICU) outcomes. Our hypothesis contends that routine assessments such as higher ASA physical status classification, surgical risk as defined by American College of Cardiology/American Heart Association guidelines, and simplified Revised Cardiac Index (SRCI) can reliably be associated with SICU outcomes.

METHODS

We performed a chart review of all patients 18 years or older admitted to the SICU between October 1, 2010, and March 1, 2011. We collected demographic and preoperative clinical data: age, sex, ASA physical status class, surgical risk, and SRCI. Outcome data included our primary end point, SICU length of stay, and secondary end points: mechanical ventilation and vasopressor treatment duration, number of acquired organ dysfunctions (NOD), readmission to the intensive care unit (ICU) within 7 days, SICU mortality, and 30-day mortality. Regression analysis and nonparametric tests were used, and P < 0.05 was considered significant.

RESULTS

We screened 239 patients and included 220 patients in the study. The patients' mean age was 58 ± 16 years. There were 32% emergent surgery and 5% readmissions to the SICU within 7 days. The SICU mortality and the 30-day mortality were 3.2%. There was a significant difference between SICU length of stay (2.9 ± 2.1 vs 5.9 ± 7.4, P = 0.007), mechanical ventilation (0.9 ± 2.0 vs 3.4 ± 6.8, P = 0.01), and NOD (0 [0-2] vs 1 [0-5], P < 0.001) based on ASA physical status class (≤ 2 vs ≥ 3). Outcomes significantly associated with ASA physical status class after adjusting for confounders were: SICU length of stay (incidence rate ratio [IRR] = 1.79, 95% confidence interval [CI], 1.35-2.39, P < 0.001), mechanical ventilation (IRR = 2.57, 95% CI, 1.69-3.92, P < 0.001), vasopressor treatment (IRR = 3.57, 95% CI, 1.84-6. 94, P < 0.001), NOD (IRR = 1.71, 95% CI, 1.46-1.99, P < 0.001), and readmission to ICU (odds ratio = 3.39, 95% CI, 1.04-11.09, P = 0.04). We found significant association between surgery risk and NOD (IRR = 1.56, 95% CI, 1.29-1.89, P < 0.001, and adjusted IRR = 1.31, 95% CI, 1.05-1.64, P = 0.02). SRCI was not significantly associated with SICU outcomes.

CONCLUSIONS

Our study revealed that ASA physical status class is associated with increased SICU length of stay, mechanical ventilation, vasopressor treatment duration, NOD, readmission to ICU, and surgery risk is associated with NOD.

Incidental abdominal aneurysms: a retrospective study of 13,115 patients who underwent a computed tomography scan

We evaluated the frequency and outcomes of abdominal aortic aneurysm (AAA) in Qatar. Data were collected retrospectively between 2004 and 2008 for all adult patients who underwent abdominal computed tomographic scanning for any reason. Patients with AAA were followed up for 3 years for aneurysmal rupture and mortality. Of the 13,115 patients screened, 61 (0.5%) patients had abdominal aneurysms. Most (82%) patients with AAA were male with mean age of 67 ± 12 years. The incidence of AAA substantially increased with age. Cardiovascular risk factors were prevalent among patients with AAA. The main location of AAA was infrarenal (67%), followed by thoracoabdominal (23%). The mean AAA diameter was 5.3 ± 2.5 cm. The rate of AAA rupture was 8% with a mortality rate of 60%; 80% of these were infrarenal, and 80% of them had a diameter of ≥5.5 cm. Overall mortality was 33%. This large study addressed the impact of screening for AAA in a population with high cardiovascular burden.

Gender differences in abdominal aortic aneurysm presentation, repair, and mortality in the Vascular Study Group of New England

OBJECTIVE

Prior studies of gender differences in abdominal aortic aneurysm (AAA) repair suggest there may be differences in presentation, suitability for endovascular aneurysm repair (EVAR), and outcomes between men and women.

METHODS

We used the Vascular Study Group of New England database to identify all patients undergoing EVAR or open AAA repair. We analyzed demographics, comorbidities, and procedural, and perioperative data. Results were compared using the Fisher exact test and the Student t-test. Multivariable logistic regression and Cox proportional hazards modeling were performed to identify predictors of mortality.

RESULTS

We identified 4026 patients (78% men) who underwent AAA repair (54% EVAR). Women were less likely than men to undergo EVAR for intact aneurysms (50% vs 60% of intact AAA repair; P < .001) but not for ruptured aneurysms (26% vs 20%; P = .23). Women were older (median age, 75 vs 72 years for intact; P < .001; 78 vs 73 years for rupture; P < .001) with smaller aortic diameters (57 vs 59 mm for elective; P < .001; 71 vs 79 mm for rupture; P < .001). Arterial injury was more common in women (5.4% vs 2.7%; P = .013) among patients undergoing EVAR for intact aneurysms. Women stayed in the hospital longer (4.3 vs 2.7 days; P = .018) and had lower odds of being discharged home, even after adjusting for age. Among patients undergoing open repair for intact aneurysms, women more frequently experienced leg ischemia/emboli (4% vs 1%; P = .001) and bowel ischemia (5% vs 3%; P = .044). Women had higher 30-day mortality after OAR for intact (4% vs 2%; P = .03) and rupture (48% vs 34%; P = .03) repairs. However, 30-day mortality after EVAR was similar for intact (1% in men vs 1% in women; P = .57) and rupture (29% in men vs 27% in women; P > .99) repairs. Late survival was worse in women than men only for patients undergoing open repair of ruptured aneurysms (hazard ratio, 1.8; 95% confidence interval, 1.0-3.1; P = .04). After controlling for age, type of repair, urgency at presentation (ie, elective/intact vs ruptured), comorbidities, and other relevant risk factors, gender was not predictive of 30-day or 1-year mortality.

CONCLUSIONS

Women with AAAs are being treated at older ages and smaller AAA diameters and are undergoing rupture repair at smaller diameters than men. Women are more likely to experience perioperative complications as a result of less favorable vascular anatomy. Age >80 years, comorbidity, presentation, and type of repair are more important predictors of mortality than gender.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Diagnosis and monitoring of abdominal aortic aneurysm: current status and future prospects

Abdominal aortic aneurysm (AAA) remains an important cause of morbidity and mortality in elderly men, and prevalence is predicted to increase in parallel with a global aging population. AAA is commonly asymptomatic, and in the absence of routine screening, diagnosis is usually incidental when imaging to assess unrelated medical complaints. In the absence of approved diagnostic and prognostic markers, AAAs are monitored conservatively via medical imaging until aortic diameter approaches 50-55 mm and surgical repair is performed. There is currently significant interest in identifying molecular markers of diagnostic and prognostic value for AAA. Here we outline the current guidelines for AAA management and discuss modern scientific techniques currently employed to identify improved diagnostic and prognostic markers.

Animal models of abdominal aortic aneurysm and their role in furthering management of human disease

Abdominal aortic aneurysm is a common degenerative disorder associated with sudden death due to aortic rupture. Current therapy is limited to open surgical repair of the aorta or endovascular placement of covered stents to exclude the abdominal aortic aneurysm from the circulation. A number of different animal models have been developed in order to study abdominal aortic aneurysm in an effort to advance current management deficiencies. Large animal models have been mostly used to assist in developing novel methods to surgically treat abdominal aortic aneurysms. Small animal models, particularly those developed in rodents, have been employed to further the understanding of the mechanisms involved in abdominal aortic aneurysm in order to identify potential new medical treatments. It is expected that findings from these animal models will contribute importantly to new treatments for human abdominal aortic aneurysm. This review explores the animal models which are used in abdominal aortic aneurysm research and highlights their advantages and disadvantages.

Gender and 30-day outcome in patients undergoing endovascular aneurysm repair (EVAR): an analysis using the ACS NSQIP dataset

PURPOSE

Prior studies have demonstrated higher in-hospital mortality in women undergoing open abdominal aortic aneurysm repair. The current study evaluates the relationship between gender and 30-day outcomes for endovascular aneurysm repair (EVAR) in a multicenter, contemporary patient population.

METHODS

Patients in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) participant use file that underwent EVAR of abdominal aortic aneurysm (AAA) from 2005 to 2007 were identified by CPT codes. Outcomes analyzed were 30-day mortality, morbidity (one or more of 21 complications defined by the ACS NSQIP protocol), length of hospital stay, and six complication subgroups. Preoperative risk factors, intraoperative variables, and outcomes were compared across genders using chi(2) (binary and categorical variables) and t tests (continuous variables). The relationship of gender to outcomes was further evaluated using multivariate logistic regressions to adjust for pre- and intraoperative risk variables.

RESULTS

In 3662 EVAR patients, 647 (17.7%) were women and 3015 (82.3%) men with mean ages of 75.1 +/- 9.0 and 73.7 +/- 8.5 years (P < .001). Tube graft (360, 9.8%); bifurcated, one docking limb (1624, 44.3%); bifurcated, two docking limbs (1294, 35.3%); unibody (218, 5.9%); and aorto-uni-iliac/femoral (166, 4.4%) repairs were performed. Tube and aorto-uni-iliac/femoral grafts were more common in women (21.4% vs 12.8%, P < .001) than men, as were femoral/femoral crossovers (3.9% vs 1.8%, P = .011) and iliac or brachial exposures (2.8% vs 1.0%, P = .009). Overall morbidity and mortality were 11.9% and 2.1%, respectively. Mortality in women was significantly higher (3.4% vs 2.1%, P = .014), as was morbidity (17.8% vs 10.6%, P < .001). Of thirteen independent preoperative risk factors for mortality or morbidity, women had a higher incidence in five: emergent operation, functional dependence, recent weight loss, underweight status or morbid obesity, and severe chronic obstructive pulmonary disease (COPD). After adjustment for these variables, the odds ratio (OR) for mortality in women vs men was 1.52 (95% confidence interval [CI] 0.85-2.69, P = .157); OR for morbidity was 1.65 (95% CI 1.28-2.14, P < .001). Female gender was also found to be an independent risk factor for length of stay (Beta 0.7 days, 95% CI 0.2-1.2, P = .006), infectious complications (OR 1.49, 95% CI 1.10-2.03, P = .011), wound complications (OR 1.80, 95% CI 1.12-2.90, P = .015) and postoperative transfusion (OR 2.92, 95% CI 1.39-6.13, P = .002).

CONCLUSIONS

Mortality and morbidity were higher in women than men undergoing EVAR. Multivariate analysis showed that the increased risk of mortality was related to women presenting more emergently, more debilitated (recent weight loss and functional dependence), and requiring iliac or brachial exposure. After adjustment for multiple preoperative and operative factors, women remained at significantly higher risk for the development of a broad range of complications and increased length of stay.