Determining the optimal interval for imaging surveillance of ascending aortic aneurysms

Unveiling cellular and molecular aspects of ascending thoracic aortic aneurysms and dissections

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM-VSMC network.

Differential expansion and outcomes of ascending and descending degenerative thoracic aortic aneurysms

OBJECTIVE

To evaluate expansion of degenerative thoracic aortic aneurysms (TAAs) and compare results between ascending and descending TAAs.

METHODS

Among patients with diagnosis of degenerative TAA (1995-2015) in Olmsted County, we studied those having at least 2 computed tomography scans of TAA throughout the follow-up. Patients were classified as ascending or descending groups according to the segment where the maximal aortic diameter was measured. Primary end points were expansion rates and factors associated with TAA growth.

RESULTS

We investigated 137 patients, 70 (51.1%) of whom were women; 78 (56.9%) were in the ascending and 59 (43.1%) were in the descending group. Median baseline maximal aortic diameter was 48.5 mm (interquartile range, 47.0-49.9 mm) for ascending and 42.4 mm (interquartile range, 40.0-45.4 mm) for descending group (P < .001). Median expansion rate was higher in the descending than the ascending group (2.0 mm/year [interquartile range, 0.9-3.2 mm/year] vs 0.2 mm/year [IQR, 0.1-0.6 mm/year]; P < .001). Aneurysm in the descending aorta and larger baseline maximal aortic diameter were independently associated with TAA expansion. Advanced age and chronic obstructive pulmonary disease but not aneurysm size or location were independently associated with overall mortality (P < .05). Aneurysm in the descending aorta was associated with aortic-related events (P < .05).

CONCLUSIONS

Degenerative TAAs under surveillance expand slowly. Descending TAA and larger baseline maximal aortic diameter were independently associated with more rapid TAA expansion, but these factors did not influence all-cause mortality.

ERS/ESTS/ESTRO/ESR/ESTI/EFOMP statement on management of incidental findings from low dose CT screening for lung cancer

BACKGROUND

Screening for lung cancer with low radiation dose computed tomography has a strong evidence base, is being introduced in several European countries and is recommended as a new targeted cancer screening programme. The imperative now is to ensure that implementation follows an evidence-based process that will ensure clinical and cost effectiveness. This European Respiratory Society (ERS) task force was formed to provide an expert consensus for the management of incidental findings which can be adapted and followed during implementation.

METHODS

A multi-European society collaborative group was convened. 23 topics were identified, primarily from an ERS statement on lung cancer screening, and a systematic review of the literature was conducted according to ERS standards. Initial review of abstracts was completed and full text was provided to members of the group for each topic. Sections were edited and the final document approved by all members and the ERS Science Council.

RESULTS

Nine topics considered most important and frequent were reviewed as standalone topics (interstitial lung abnormalities, emphysema, bronchiectasis, consolidation, coronary calcification, aortic valve disease, mediastinal mass, mediastinal lymph nodes and thyroid abnormalities). Other topics considered of lower importance or infrequent were grouped into generic categories, suitable for general statements.

CONCLUSIONS

This European collaborative group has produced an incidental findings statement that can be followed during lung cancer screening. It will ensure that an evidence-based approach is used for reporting and managing incidental findings, which will mean that harms are minimised and any programme is as cost-effective as possible.

ERS/ESTS/ESTRO/ESR/ESTI/EFOMP statement on management of incidental findings from low dose CT screening for lung cancer

BACKGROUND

Screening for lung cancer with low radiation dose computed tomography has a strong evidence base, is being introduced in several European countries and is recommended as a new targeted cancer screening programme. The imperative now is to ensure that implementation follows an evidence-based process that will ensure clinical and cost effectiveness. This European Respiratory Society (ERS) task force was formed to provide an expert consensus for the management of incidental findings which can be adapted and followed during implementation.

METHODS

A multi-European society collaborative group was convened. 23 topics were identified, primarily from an ERS statement on lung cancer screening, and a systematic review of the literature was conducted according to ERS standards. Initial review of abstracts was completed and full text was provided to members of the group for each topic. Sections were edited and the final document approved by all members and the ERS Science Council.

RESULTS

Nine topics considered most important and frequent were reviewed as standalone topics (interstitial lung abnormalities, emphysema, bronchiectasis, consolidation, coronary calcification, aortic valve disease, mediastinal mass, mediastinal lymph nodes and thyroid abnormalities). Other topics considered of lower importance or infrequent were grouped into generic categories, suitable for general statements.

CONCLUSIONS

This European collaborative group has produced an incidental findings statement that can be followed during lung cancer screening. It will ensure that an evidence-based approach is used for reporting and managing incidental findings, which will mean that harms are minimised and any programme is as cost-effective as possible.

The Maastricht Acquisition Platform for Studying Mechanisms of Cell-Matrix Crosstalk (MAPEX): An Interdisciplinary and Systems Approach towards Understanding Thoracic Aortic Disease

Current management guidelines for ascending thoracic aortic aneurysms (aTAA) recommend intervention once ascending or sinus diameter reaches 5-5.5 cm or shows a growth rate of >0.5 cm/year estimated from echo/CT/MRI. However, many aTAA dissections (aTAAD) occur in vessels with diameters below the surgical intervention threshold of <55 mm. Moreover, during aTAA repair surgeons observe and experience considerable variations in tissue strength, thickness, and stiffness that appear not fully explained by patient risk factors. To improve the understanding of aTAA pathophysiology, we established a multi-disciplinary research infrastructure: The Maastricht acquisition platform for studying mechanisms of tissue-cell crosstalk (MAPEX). The explicit scientific focus of the platform is on the dynamic interactions between vascular smooth muscle cells and extracellular matrix (i.e., cell-matrix crosstalk), which play an essential role in aortic wall mechanical homeostasis. Accordingly, we consider pathophysiological influences of wall shear stress, wall stress, and smooth muscle cell phenotypic diversity and modulation. Co-registrations of hemodynamics and deep phenotyping at the histological and cell biology level are key innovations of our platform and are critical for understanding aneurysm formation and dissection at a fundamental level. The MAPEX platform enables the interpretation of the data in a well-defined clinical context and therefore has real potential for narrowing existing knowledge gaps. A better understanding of aortic mechanical homeostasis and its derangement may ultimately improve diagnostic and prognostic possibilities to identify and treat symptomatic and asymptomatic patients with existing and developing aneurysms.

Cost-effectiveness of Follow-up CT for Incidental Ascending Aortic Dilatation

Purpose

To evaluate the cost-effectiveness of CT follow-up strategies for incidental aortic dilatation.

Materials and Methods

In this cost-effectiveness analysis, a simulation model was developed with 1 000 000 adult patients aged 55-75 years with incidentally detected dilated aortas measuring 40-50 mm. Follow-up CT strategies were evaluated for various patient age- and aortic size-based cutoffs. Follow-up frequency ranged from 1 to 3 years, as well as a single follow-up CT examination at 1 year. Patient survival was determined by risk of aortic dissection or rupture and surgical- and age-based mortality. Costs and quality-adjusted life-years (QALYs) were calculated for each strategy within the simulated cohort. A probabilistic sensitivity analysis was performed by varying model parameters.

Results

The cost-effective strategy with the highest QALYs under a willingness-to-pay threshold of $100 000 per QALY was follow-up CT for patients younger than 60 years with aortas measuring at least 40 mm in diameter every 3 years (incremental cost-effectiveness ratio, $62 511; 95% CI: $52 168, $77 739). With this strategy, follow-up imaging was needed for only 17% of dilated aortas in the cohort. Probabilistic sensitivity analysis demonstrated that the cost-effective strategies at $100 000 per QALY threshold included the following: no follow-up for patients with aortas smaller than 50 mm (39% of simulations), follow-up every 3 years for patients younger than 55 years with aortas measuring at least 45 mm (21%), and follow-up every 3 years for patients older than 65 years with aortas measuring at least 40 mm (14%).

Conclusion

Follow-up CT for an incidentally detected dilated ascending aorta smaller than 50 mm is likely not cost-effective in patients older than 60-65 years.Keywords: CT, Thorax, Vascular, Aorta, Cost-Effectiveness, Cost-Benefit Analysis Supplemental material is available for this article. © RSNA, 2023See also commentary by Shen and Fleischmann in this issue.

Assessment of shape-based features ability to predict the ascending aortic aneurysm growth

The current guidelines for the ascending aortic aneurysm (AsAA) treatment recommend surgery mainly according to the maximum diameter assessment. This criterion has already proven to be often inefficient in identifying patients at high risk of aneurysm growth and rupture. In this study, we propose a method to compute a set of local shape features that, in addition to the maximum diameter D, are intended to improve the classification performances for the ascending aortic aneurysm growth risk assessment. Apart from D, these are the ratio DCR between D and the length of the ascending aorta centerline, the ratio EILR between the length of the external and the internal lines and the tortuosity T. 50 patients with two 3D acquisitions at least 6 months apart were segmented and the growth rate (GR) with the shape features related to the first exam computed. The correlation between them has been investigated. After, the dataset was divided into two classes according to the growth rate value. We used six different classifiers with input data exclusively from the first exam to predict the class to which each patient belonged. A first classification was performed using only D and a second with all the shape features together. The performances have been evaluated by computing accuracy, sensitivity, specificity, area under the receiver operating characteristic curve (AUROC) and positive (negative) likelihood ratio LHR+ (LHR-). A positive correlation was observed between growth rate and DCR (r = 0.511, p = 1.3e-4) and between GR and EILR (r = 0.472, p = 2.7e-4). Overall, the classifiers based on the four metrics outperformed the same ones based only on D. Among the diameter-based classifiers, k-nearest neighbours (KNN) reported the best accuracy (86%), sensitivity (55.6%), AUROC (0.74), LHR+ (7.62) and LHR- (0.48). Concerning the classifiers based on the four shape features, we obtained the best accuracy (94%), sensitivity (66.7%), specificity (100%), AUROC (0.94), LHR+ (+∞) and LHR- (0.33) with support vector machine (SVM). This demonstrates how automatic shape features detection combined with risk classification criteria could be crucial in planning the follow-up of patients with ascending aortic aneurysm and in predicting the possible dangerous progression of the disease.

National trends in thoracic aortic aneurysms and dissections in patients with Marfans and Ehlers Danlos syndrome

INTRODUCTION

Connective tissue disorders predispose patients to earlier aortic dissections and aneurysms. However, there is limited large cohort data given its low incidence.

METHODS

The National Inpatient Sample was searched for all adults with Marfans (MFS) and Ehlers Danlos (EDS) disease between 2010 and 2017. ICD codes were used to select those with a type A aortic dissection or aneurysm.

RESULTS

There was a total of 19,567 cases, giving the estimated incidence of MFS and EDS of 18 and 22.4 per 100k people, respectively. After inclusion criteria, there were 2553 MF and 180 EDS patients. There was no statistical difference in mortality between the MFS and EDS cohorts (4.6% vs. 2.8%, p = .26). EDS patients were more likely to undergo a TEVAR procedure (2.8% vs. 1.0%, p = .03). MF patients were more likely to have a complication of acute kidney injury (p = .02). EDS patients were more likely older (50 vs. 42, p < .001) and female (47% vs. 33%, p < .001). MFS patients were more likely to have a type A aortic dissection (44% vs. 31%, p < .001). The majority (89%) of patients were treated at urban teaching hospitals. On univariable logistic regression, aortic dissection was a predictor for mortality (odds ratio 7.31, p < .001). The type of connective tissue disease was not a significant predictor.

CONCLUSIONS

National level estimates show low mortality for patients with MF or ED presenting to the hospital with aortic dissection or aneurysm. The differences in age and gender can guide surveillance for these patient populations, leading to more elective admissions and reduced hospital mortality.