Is there a role for biomarkers in thoracic aortic aneurysm disease?

Dysregulated homocysteine metabolism and cardiovascular disease and clinical treatments

Elevated homocysteine (Hcy) levels, known as hyperhomocysteinemia (HHcy), are recognized as a separate risk factor for cardiovascular disease. Mutations in methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta synthase (CBS)-enzymes pivotal at the juncture of the trans-sulfuration and remethylation pathways-underlie the pathogenesis of HHcy. Although vitamin supplementation has been proven to effectively decrease Hcy levels, there is still uncertainty about whether this reduction translates to a decrease in the incidence rates from cardiovascular diseases (CVDs). This review seeks to explore the linking between Hcy and specific diseases, the role of Hcy in vascular homeostasis, and the research on the possible advantages of therapies designed to lower Hcy levels. Understanding the intricate mechanisms of their metabolism and interactions is essential for pharmacological treatments to mitigate the adverse effects associated with metabolic dysregulation of Hcy. Given the widespread availability and ease of use of Hcy test kits, we strongly advocate for the routine administration of rapid blood tests for individuals at high risk of CVDs, particularly among the elderly population.

Thoracic Aortic Aneurysm Growth Rates and Predicting Factors: A Systematic Review and Meta-Analysis

BACKGROUND

Thoracic aortic aneurysm (TAA) is an indolent, potentially fatal disease, which progresses at variable rates that are influenced by pathogenesis and patient characteristics. We conducted a systematic review and meta-analysis to synthesize the current evidence on growth rate (GR) and predictive factors among patients with syndromic and nonsyndromic heritable thoracic aortic disease, bicuspid aortic valve, and sporadic TAA.

METHODS AND RESULTS

Online databases were searched for studies that reported aortic growth on adult patients with asymptomatic TAA. Pooled GRs were calculated for 3 different TAA groups: syndromic heritable thoracic aortic disease, bicuspid aortic valve, and sporadic TAA. The search yielded 6297 studies, of which 85 were included in the systematic review, and 55 in the meta-analysis of growth rate (10 syndromic heritable thoracic aortic disease, 31 bicuspid aortic valve, and 34 sporadic subgroups). Mean observed TAA GR was 0.25 mm/y (95% CI, -0.18 to 0.68) in Turner syndrome, 0.45 mm/y (95% CI, 0.00-0.90) in Marfan syndrome, and 0.81 mm/y (95% CI, -0.46 to 2.08) in Loeys-Dietz syndrome. The mean observed GR in patients with bicuspid aortic valve before aortic valve surgery was 0.37 mm/y (95% CI, 0.29-0.46), compared with 0.18 mm/y (95% CI, 0.14-0.33) in postsurgical studies. Mean observed GR in sporadic ascending TAA was 0.33 mm/y (95% CI, 0.13-0.52) and 2.71 mm/y (95% CI, 0.53-4.88) in descending TAA.

CONCLUSIONS

Considering all pathogeneses, ascending TAAs typically grow at 0.25 to 1 mm/y, and thus annual surveillance is likely too frequent to detect growth in most patients. Studies vary widely in populations, methodology, and outcomes, with few high-quality longitudinal studies and no predictors of aortic GR.

A Narrative Review: Syndecans in Aortic Aneurysm Pathogenesis and Course-Biomarkers and Targets?

The maintenance of the integrity of the entire endothelium, glycocalyx included, and, therefore, of tissue aorta's homeostasis, depends on the expressions of several molecular pathways and their interactions, such as syndecan molecules. Alterations in syndecans, i.e., quantitative alterations or linking to their shedding, contributes to invoking endothelium dysfunction, which causes damage to the vessel wall due to the increased production of growth-stimulating and pro-inflammatory gene products. Inflammatory processes negatively affect the integrity of the endothelial glycocalyx, a dynamic layer of the luminal portion of endothelial cells composed of proteoglycans, glycoproteins, and glycosaminoglycans, i.e., syndecans. In turn, structural alterations in the endothelial glycocalyx influence the coagulative state, increasing pro-thrombotic processes. The family of syndecans constitutes a major component of glycocalyx or, more accurately, the major source of cell surface heparan sulfate. It encompasses four components: syndecan-1, syndecan-2, and syndecan-4 (with syndecan-3 only expressed in neural tissue), which have a fundamental role in regulating the events of acute and chronic aorta damage subsequently correlated with the formation of aneurysms. As such, the aim of our review is to highlight the current knowledge on the roles of syndecans and to analyze their relationship with the pathological processes of the aortic wall based on the most recent literature.

Aortic aneurysm: Correlations with phenotypes associated with connective tissue dysplasia

An aortic aneurysm is a localized enlargement that exceeds the normal diameter of the vessel by 50 %, posing a risk due to the likelihood of rupture. The cause of aortic aneurysm, especially in young people, is connective tissue dysplasia, a condition characterized by defects in the assembly of collagen and elastin proteins, leading to changes in elastic properties and disruption of the formation of organs and their systems. The article presents data confirming the relationship between many morphological manifestations of connective tissue dysplasia (e.g., funnel-shaped deformation of the sternum, scoliosis of the thoracic spine, abdominal hernias, arterial tortuosity, striae of atypical localization) and the risk of aortic aneurysm formation. The literature suggests that the identified combinations of some external manifestations of connective tissue dysplasia deserve special attention and may be constitutional markers for the possible development of aortic aneurysm, which is a promising direction for further research in this area.

Soluble Proteoglycans and Proteoglycan Fragments as Biomarkers of Pathological Extracellular Matrix Remodeling

Proteoglycans and their proteolytic fragments diffuse into biological fluids such as plasma, serum, urine, or synovial fluid, where they can be detected by antibodies or mass-spectrometry. Neopeptides generated by the proteolysis of proteoglycans are recognized by specific neoepitope antibodies and can act as a proxy for the activity of certain proteases. Proteoglycan and proteoglycan fragments can be potentially used as prognostic, diagnostic, or theragnostic biomarkers for several diseases characterized by dysregulated extracellular matrix remodeling such as osteoarthritis, rheumatoid arthritis, atherosclerosis, thoracic aortic aneurysms, central nervous system disorders, viral infections, and cancer. Here, we review the main mechanisms accounting for the presence of soluble proteoglycans and their fragments in biological fluids, their potential application as diagnostic, prognostic, or theragnostic biomarkers, and highlight challenges and opportunities ahead of their clinical translation.

Risk factors and predictive indicators of rupture in cerebral aneurysms

Cerebral aneurysms are abnormal dilations of blood vessels in the brain that have the potential to rupture, leading to subarachnoid hemorrhage and other serious complications. Early detection and prediction of aneurysm rupture are crucial for effective management and prevention of rupture-related morbidities and mortalities. This review aims to summarize the current knowledge on risk factors and predictive indicators of rupture in cerebral aneurysms. Morphological characteristics such as aneurysm size, shape, and location, as well as hemodynamic factors including blood flow patterns and wall shear stress, have been identified as important factors influencing aneurysm stability and rupture risk. In addition to these traditional factors, emerging evidence suggests that biological and genetic factors, such as inflammation, extracellular matrix remodeling, and genetic polymorphisms, may also play significant roles in aneurysm rupture. Furthermore, advancements in computational fluid dynamics and machine learning algorithms have enabled the development of novel predictive models for rupture risk assessment. However, challenges remain in accurately predicting aneurysm rupture, and further research is needed to validate these predictors and integrate them into clinical practice. By elucidating and identifying the various risk factors and predictive indicators associated with aneurysm rupture, we can enhance personalized risk assessment and optimize treatment strategies for patients with cerebral aneurysms.

Differentiation between descending thoracic aortic diseases using machine learning and plasma proteomic signatures

BACKGROUND

Descending thoracic aortic aneurysms and dissections can go undetected until severe and catastrophic, and few clinical indices exist to screen for aneurysms or predict risk of dissection.

METHODS

This study generated a plasma proteomic dataset from 75 patients with descending type B dissection (Type B) and 62 patients with descending thoracic aortic aneurysm (DTAA). Standard statistical approaches were compared to supervised machine learning (ML) algorithms to distinguish Type B from DTAA cases. Quantitatively similar proteins were clustered based on linkage distance from hierarchical clustering and ML models were trained with uncorrelated protein lists across various linkage distances with hyperparameter optimization using fivefold cross validation. Permutation importance (PI) was used for ranking the most important predictor proteins of ML classification between disease states and the proteins among the top 10 PI protein groups were submitted for pathway analysis.

RESULTS

Of the 1,549 peptides and 198 proteins used in this study, no peptides and only one protein, hemopexin (HPX), were significantly different at an adjusted p < 0.01 between Type B and DTAA cases. The highest performing model on the training set (Support Vector Classifier) and its corresponding linkage distance (0.5) were used for evaluation of the test set, yielding a precision-recall area under the curve of 0.7 to classify between Type B from DTAA cases. The five proteins with the highest PI scores were immunoglobulin heavy variable 6-1 (IGHV6-1), lecithin-cholesterol acyltransferase (LCAT), coagulation factor 12 (F12), HPX, and immunoglobulin heavy variable 4-4 (IGHV4-4). All proteins from the top 10 most important groups generated the following significantly enriched pathways in the plasma of Type B versus DTAA patients: complement activation, humoral immune response, and blood coagulation.

CONCLUSIONS

We conclude that ML may be useful in differentiating the plasma proteome of highly similar disease states that would otherwise not be distinguishable using statistics, and, in such cases, ML may enable prioritizing important proteins for model prediction.

Clinical features and risk factors of primary Sjögren's syndrome complicated with severe pneumonia: a case-control study

OBJECTIVES

To analyze clinical characteristics, risk factors, pathogen distribution, and prognostic markers in primary Sjögren's syndrome (pSS) patients with severe pneumonia (SP) compared to those without severe pneumonia (NSP).

METHODS

This case-control study included 24 hospitalized pSS patients with SP and 96 NSP at the first affiliated hospital of Soochow university from June 2014 to May 2023. Data encompassing demographics, comorbidities, treatments, and laboratory results were retrospectively collected. Univariate and multivariate regression analyses, ROC curves, and statistical analyses using SPSS 23.0 assessed risk factors. The study retrospectively analyzed clinical features and risk factors, highlighting distinct parameters between pSS patients with and without SP.

RESULTS

Marked differences were observed in several parameters: pSS activity(P < 0.001), white blood cell (P = 0.043), lymphocyte (P < 0.001), neutrophils (P = 0.042), C-reactive protein (P = 0.042), and CD8+ T cell (P = 0.017). Notably, lymphocyte count and SS activity demonstrated robust discrimination ability (AUC > 0.85). C-reactive protein (CRP), procalcitonin, CD4+ T cell, and IgA showed significant associations with SP; higher CRP levels correlated with increased risk, while lower CD4+ T cell and IgA levels associated with increased risk. SS activity significantly impacted outcomes. Various biomarkers exhibited diverse discriminatory abilities but lacked strong predictive associations with outcomes.

CONCLUSION

pSS patients with SP exhibited higher disease activity and altered immune profiles compared to those NSP. Lymphocyte count and SS activity emerged as robust discriminators. Higher CRP levels correlated with increased risk of SP, while lower CD4+T cell and IgA levels associated with increased risk. SS activity significantly impacted patient outcomes. Key Points • pSS patients with SP exhibited higher disease activity and altered immune profiles compared to those NSP. • Lymphocyte count and SS activity emerged as robust discriminators. • Higher CRP levels correlated with increased risk of SP, while lower CD4+ T cell and IgA levels associated with decreased risk. • SS activity significantly impacted patient outcomes.

CircCDYL Contributes to Apoptosis, Ferroptosis, and Oxidative Stress of Ang II-Induced Vascular Smooth Muscle Cells in Thoracic Aortic Aneurysm

Circular RNAs (circRNAs) have important regulation in thoracic aortic aneurysm (TAA). The function and mechanism of circCDYL (circ_0008285) was explored in TAA here. Angiotensin II (Ang II) was used to construct a TAA model. Real-time quantitative polymerase chain reaction (RT-qPCR) was performed for the detection of circCDYL, miR-1270, and a disintegrin and metalloproteinase 10 (ADAM10). Cell viability was examined via cell counting kit-8 (CCK-8) assay and proliferation was analyzed using Ethynyl-2'-deoxyuridine (EdU) assay. Apoptosis rate was assessed via flow cytometry. Western blot was used for protein detection. Oxidative stress was evaluated by commercial kits. CircCDYL was upregulated in TAA tissues and Ang II-induced circCDYL upregulation in vascular smooth muscle cells (VSMCs). Knockdown of circCDYL weakened Ang II-aroused inhibition of viability, proliferation, and promotion of apoptosis, ferroptosis, and oxidative stress in VSMCs. CircCDYL served as a miR-1270 sponge. The mitigated regulation of circCDYL knockdown for Ang II-induced injury was restored after miR-1270 downregulation. CircCDYL positively regulated ADAM10 through interacting with miR-1270. Overexpression of miR-1270 abated Ang II-induced injury by downregulating ADAM10. In conclusion, circCDYL was involved in the Ang II-induced VSMC injury in TAA via the miR-1270/ADAM10 axis.

Male-female differences in thoracic aortic diameters at presentation of acute type A aortic dissection

Background

Acute type A aortic dissection (ATAAD) is a highly lethal event, associated with aortic dilatation. It is not well known if patient height, weight or sex impact the thoracic aortic diameter (TAA) at ATAAD. The study aim was to identify male-female differences in TAA at ATAAD presentation.

Methods

This retrospective cross-sectional study analysed all adult patients who presented with ATAAD between 2007 and 2017 in two tertiary care centres and underwent contrast enhanced computed tomography (CTA) before surgery. Absolute aortic diameters were measured at the sinus of Valsalva (SoV), ascending (AA) and descending thoracic aorta (DA) using double oblique reconstruction, and indexed for body surface area (ASI) and height (AHI). Z-scores were calculated using the Campens formula.

Results

In total, 59 % (181/308) of ATAAD patients had CT-scans eligible for measurements, with 82 female and 99 male patients. Females were significantly older than males (65.5 ± 12.4 years versus 60.3 ± 2.3, p = 0.024). Female patients had larger absolute AA diameters than male patients (51.0 mm [47.0-57.0] versus 49.0 mm [45.0-53.0], p = 0.023), and larger ASI and AHI at all three levels. Z-scores for the SoV and AA were significantly higher for female patients (2.99 ± 1.66 versus 1.34 ± 1.77, p < 0.001 and 5.27 [4.38-6.26] versus 4.06 [3.14-5.02], p < 0.001). After adjustment for important clinical factors, female sex remained associated with greater maximal TAA (p = 0.019).

Conclusion

Female ATAAD patients had larger absolute ascending aortic diameters than males, implying a distinct timing in disease presentation or selection bias. Translational studies on the aortic wall and studies on growth patterns should further elucidate these sex differences.

Label-free quantitative proteomic analysis of serum exosomes in mice with thoracic aortic aneurysm

OBJECTIVE

Thoracic aortic aneurysm (TAA) is a cardiovascular disease with high morbidity and mortality. However, the causes and mechanisms of TAA are not fully understood. Serum exosomes from mice with TAA were used to explore the markers associated with this disease.

METHODS

C57BL/6 mice were divided into three groups and given ordinary drinking water, ordinary drinking water plus a saline osmotic pump, or drinking water containing β-aminopropionitrile (BAPN) (1 g/kg/d) plus an angiotensin II (Ang II) (1 μg/kg/min) osmotic pump. Haematoxylin and eosin staining of thoracic aortic tissues was performed. The basic characteristics of exosomes were analysed. Differentially expressed proteins (DEPs) were identified by LC‒MS/MS. Protein‒protein networks and enrichment analysis were used to explore possible molecular mechanisms.

RESULTS

The present study elucidated the protein expression profile of serum exosomes in mice with TAA induced by BAPN combined with Ang II. In this work, the expression of a total of 196 proteins was significantly dysregulated in serum exosomes of mice with TAA, with 122 proteins significantly upregulated and 74 proteins markedly downregulated. Notably, Haptoglobin (Hp) and Serum amyloid p-component (Sap) identified based on the PPI network were significantly upregulated and have been strongly linked to cardiovascular disease. Interestingly, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the upregulated and downregulated proteins were involved in the complement and coagulation cascade pathways.

CONCLUSIONS

This study showed that the identified DEPs have potential as biomarkers for the diagnosis of TAA and provided a more comprehensive understanding of the pathophysiological mechanisms of TAA.

Differentiation between Descending Thoracic Aortic Diseases using Machine Learning and Plasma Proteomic Signatures

Background

Descending thoracic aortic aneurysms and dissections can go undetected until severe and catastrophic, and few clinical indices exist to screen for aneurysms or predict risk of dissection.

Methods

This study generated a plasma proteomic dataset from 75 patients with descending type B dissection (Type B) and 62 patients with descending thoracic aortic aneurysm (DTAA). Standard statistical approaches were compared to supervised machine learning (ML) algorithms to distinguish Type B from DTAA cases. Quantitatively similar proteins were clustered based on linkage distance from hierarchical clustering and ML models were trained with uncorrelated protein lists across various linkage distances with hyperparameter optimization using 5-fold cross validation. Permutation importance (PI) was used for ranking the most important predictor proteins of ML classification between disease states and the proteins among the top 10 PI protein groups were submitted for pathway analysis.

Results

Of the 1,549 peptides and 198 proteins used in this study, no peptides and only one protein, hemopexin (HPX), were significantly different at an adjusted p-value <0.01 between Type B and DTAA cases. The highest performing model on the training set (Support Vector Classifier) and its corresponding linkage distance (0.5) were used for evaluation of the test set, yielding a precision-recall area under the curve of 0.7 to classify between Type B from DTAA cases. The five proteins with the highest PI scores were immunoglobulin heavy variable 6-1 (IGHV6-1), lecithin-cholesterol acyltransferase (LCAT), coagulation factor 12 (F12), HPX, and immunoglobulin heavy variable 4-4 (IGHV4-4). All proteins from the top 10 most important correlated groups generated the following significantly enriched pathways in the plasma of Type B versus DTAA patients: complement activation, humoral immune response, and blood coagulation.

Conclusions

We conclude that ML may be useful in differentiating the plasma proteome of highly similar disease states that would otherwise not be distinguishable using statistics, and, in such cases, ML may enable prioritizing important proteins for model prediction.

The Role of ADAMTS Proteoglycanases in Thoracic Aortic Disease

Thoracic aortic aneurysm and dissection (TAAD) are complex disease states with high morbidity and mortality that pose significant challenges to early diagnosis. Patients with an aneurysm are asymptomatic and typically present to the emergency department only after the development of a dissection. The extracellular matrix (ECM) plays a crucial role in regulating the aortic structure and function. The histopathologic hallmark termed medial degeneration is characterised by smooth muscle cell (SMC) loss, the degradation of elastic and collagen fibres and proteoglycan (PG) accumulation. Covalently attached to the protein core of PGs are a number of glycosaminoglycan chains, negatively charged molecules that provide flexibility, compressibility, and viscoelasticity to the aorta. PG pooling in the media can produce discontinuities in the aortic wall leading to increased local stress. The accumulation of PGs is likely due to an imbalance between their synthesis by SMCs and decreased proteolysis by A Disintegrin-like and Metalloproteinase with Thrombospondin motifs (ADAMTS) proteoglycanases in the ECM. Mouse models of TAAD indicated that these proteases exert a crucial, albeit complex and not fully elucidated, role in this disease. This has led to a mounting interest in utilising ADAMTS proteoglycanases as biomarkers of TAAD. In this review, we discuss the role of ADAMTSs in thoracic aortic disease and their potential use in facilitating the clinical diagnosis of TAAD and disease progression.

Circulating biomarkers associated with aortic diameter in male and female patients with thoracic aortic disease: a cross-sectional study

OBJECTIVE

As thoracic aortic disease (TAD) is generally asymptomatic, biomarkers are needed to provide insight into early progression. We aimed to examine the association between circulating blood biomarkers and the maximal thoracic aortic diameter (TADmax).

METHODS

In this cross-sectional study, consecutive adult patients with a thoracic aortic diameter ≥40 mm and/or genetically proven hereditary TAD (HTAD) visiting our specialised outpatient clinic between 2017 and 2020 were prospectively included. Venous blood sampling and CT angiography and/or transthoracic echocardiography of the aorta were performed. Linear regression analyses were performed and estimates were presented as mean difference in TADmax in mm per doubling of standardised biomarker level.

RESULTS

In total, 158 patients were included (median age 61 (50.3-68.8) years, 37.3% female). HTAD diagnosis was confirmed in 36 of 158 (22.7%) patients. TADmax was 43.9±5.2 mm in men vs 41.9±5.1 in women (p=0.030). In unadjusted analysis, significant associations with TADmax were found for interleukin-6 (1.15 (95% CI 0.33 to 1.96), p=0.006), growth differentiation factor-15 (1.01 (95% CI 0.18 to 1.84), p=0.018), microfibrillar-associated protein 4 (MFAP4) (-0.88 (95% CI -1.71 to 0.05), p=0.039) and triiodothyronine (T3) (-2.00 (95%CI -3.01 to 0.99), p<0.001). The association of MFAP4 with TADmax was stronger in women (p for interaction=0.020) and for homocysteine, an inverse association with TADmax was observed when compared with men (p for interaction=0.008). When adjusted for age, sex, hyperlipidaemia and HTAD, total cholesterol (1.10 (95% CI 0.27 to 1.93), p=0.010) and T3 (-1.20 (95% CI -2.14 to 0.25), p=0.014) were significantly associated with TADmax.

CONCLUSIONS

Circulating biomarkers indicative of inflammation, lipid metabolism and thyroid function might be associated with TAD severity. Possible distinct biomarker patterns for men and women warrant further investigation.

Novel biomarkers associated with thoracic aortic disease

BACKGROUND

Biomarkers might help to improve diagnosis, surveillance and risk stratification of thoracic aortic disease (TAD). We explored the association between a broad spectrum of cardiovascular biomarkers with clinical characteristics and thoracic aortic diameter in TAD patients.

METHODS

Venous blood-samples were obtained in 158 clinically stable TAD patients visiting our outpatient clinic (2017-2020). TAD was defined as a thoracic aortic diameter ≥ 40 mm, or genetic confirmation (hereditary TAD). The cardiovascular panel III of the Olink multiplex platform was used for batch analysis of 92 proteins. A comparison was made between biomarker levels in patients with and without previous aortic dissection and/or surgery, and with and without hereditary TAD. Linear regression analyses were applied to identify (relative, normalized) biomarker concentrations associated with the absolute thoracic aortic diameter (AD_max), and thoracic aortic diameter indexed for body surface area (ID_max).

RESULTS

Median age of study patients was 61.0 (IQR 50.3-68.8) years, 37.3% females. Mean AD_max and ID_max were 43.3 ± 5.4 mm and 21.3 ± 3.3 mm/m². After multivariable adjustment, Matrix Metalloproteinase-3 (MMP-3) and Insulin-like growth factor binding protein 2 (IGFBP-2) showed a significant positive association with AD_max and ID_max, respectively. Patients with previous aortic surgery/dissection had higher N-terminal-pro hormone BNP (NTproBNP) (median 3.67 [IQR 3.01-3.99] vs 2.84 [2.32-3.26], p ≤0.001). Patients with hereditary TAD had higher Trem-like transcript protein 2 (TLT-2) (median 4.64 [IQR 4.45-4.84]) than those with non-heriditary TAD (4.40 [4.17-4.64]; p = 0.00042).

CONCLUSIONS

Among a broad range of biomarkers, MMP-3 and IGFBP-2 were associated with disease severity in TAD patients. The pathophysiological pathways uncovered by these biomarkers, and their potential clinical use warrants further research.

Prevalence and development of aortic dilation and dissection in women with Turner syndrome: a systematic review and meta-analysis

OBJECTIVES

Women with Turner syndrome (TS) have an increased risk of aortic disease, reducing life-expectancy. This study aimed to systematically review the prevalence of thoracic aortic dilatation, aortic dimensions and growth, and the incidence of aortic dissection.

METHODS

A systematic literature search was conducted up to July 2022. Observational studies with an adult TS population were included, and studies including children aged <15 years old or specific TS populations were excluded.

RESULTS

In total 21 studies were included. The pooled prevalence of ascending aortic dilatation was 23% (95% CI 19-26) at a mean pooled age of 29 years (95% CI 26-32), while the incidence of aortic dissection was 164 per 100.000 patient-years (95% CI 95-284). Three reporting studies showed aortic growth over time to be limited. Risk factors for aortic dilation or dissection were older age, bicuspid aortic valve, aortic coarctation, and hypertension.

CONCLUSION

In adult TS women, ascending aortic dilatation is common and the hazard of aortic dissection increased compared to the general population, whereas aortic growth is limited. Conventional risk markers do not explain all aortic dissection cases; therefore, new imaging parameters and blood biomarkers are needed to improve prediction, allowing for patient-tailored follow-up and surgical decision-making.

Circulating fibrillin fragment concentrations in patients with and without aortic pathology

Objective

Fragments of fibrillin-1 and fibrillin-2 will be detectable in the plasma of patients with aortic dissections and aneurysms. We sought to determine whether the plasma fibrillin fragment levels (PFFLs) differ between patients with thoracic aortic pathology and those presenting with nonaortic chest pain.

Methods

PFFLs were measured in patients with thoracic aortic aneurysm (n = 27) or dissection (n = 28). For comparison, patients without aortic pathology who had presented to the emergency department with acute chest pain (n = 281) were categorized into three groups according to the cause of the chest pain: ischemic cardiac chest pain; nonischemic cardiac chest pain; and noncardiac chest pain. The PFFLs were measured using a sandwich enzyme-linked immunosorbent assay.

Results

Fibrillin-1 fragments were detectable in all patients and were lowest in the ischemic cardiac chest pain group. Age, sex, and the presence of hypertension were associated with differences in fibrillin-1 fragment levels. Fibrillin-2 fragments were detected more often in the thoracic aneurysm and dissection groups than in the emergency department chest pain group (P < .0001). Patients with aortic dissection demonstrated a trend toward increased detectability (P = .051) and concentrations (P = .06) of fibrillin-2 fragments compared with patients with aortic aneurysms. Analysis of specific antibody pairs identified fibrillin-1 B15-HRP26 and fibrillin-2 B205-HRP143 as the most informative in distinguishing between the emergency department and aortic pathology groups.

Conclusions

Patients with thoracic aortic dissections demonstrated elevated plasma fibrillin-2 fragment levels (B205-HRP143) compared with patients presenting with ischemic or nonischemic cardiac chest pain and increased fibrillin-1 levels (B15-HRP26) compared with patients with ischemic cardiac chest pain. Investigation of fibrillin-1 and fibrillin-2 fragment generation might lead to diagnostic, therapeutic, and prognostic advances for patients with thoracic aortic dissection.

Neuroprotection in aortic arch surgery: untold flaws and future directions

The current paradigm of brain protection in aortic surgery falls short of delivering good outcomes with minimal complications. A renewed understanding of neuroprotective methods and biomarkers to predict brain injury and aortic disease are crucial towards the development of more effective clinical management strategies. A review of current literature was carried out to identify current flaws in our approach to neuroprotection in aortic surgery. Emerging evidence surrounding neuroprotective strategies, biomarkers for brain injury, and biomarkers for predicting aortic disease are evaluated in terms of their impact for future therapeutic approaches. Current literature suggests that the prevailing methods of neuroprotection need renewal. Clinical outcomes associated with deep hypothermic circulatory arrest remain varied. Branch-first and endovascular approaches to aortic repair are particularly promising alternatives. The use of biomarkers to identify and manage brain injury, as well as to diagnose aortic disease in the nonacute and acute settings, would further help to improve our overall paradigm of neuroprotection in aortic surgery. Though much prospective research is still required, the outlook for neuroprotection in aortic surgery is promising. Adopting alternative surgical techniques and exploiting predictive novel biomarkers will help us to gradually eliminate the risk of brain damage in aortic surgery.

Duration of deep hypothermic circulatory arrest for aortic arch surgery: is it a myth, fiction, or scientific leap?

INTRODUCTION

The use of deep hypothermic circulatory arrest (DHCA) to provide aortic surgeons with a bloodless operative field while simultaneously protecting the brain and peripheries from ischemic damage revolutionized cardiac and aortic surgery, and is currently used in specialist centers across the globe. However, it is associated with manifold adverse outcomes, including neurocognitive dysfunction and mortality. This review seeks to analyze the relationship between DHCA duration and clinical outcome, and evaluate the controversies and limitations surrounding its use.

EVIDENCE ACQUISITION

We performed a review of available literature with statistical analysis to evaluate the relationship between DHCA duration (<40 min and >40 min) and key clinical outcomes, including mortality, permanent and temporary neurological deficit, renal damage, admission length, and reintervention rate. The controversies surrounding DHCA use and future directions for care are also explored.

EVIDENCE SYNTHESIS

Statistical analysis revealed no significant association (P>0.05) between DHCA duration and clinical outcomes (early and late mortality rates, neurological deficit, admission length, and reintervention rate), both with and without adjunctive perfusion techniques.

CONCLUSIONS

Available literature suggests that the relationships between DHCA duration (with and without adjunctive perfusion) and clinical outcomes are unclear, and at present not statistically significant. Alternative surgical and endovascular techniques have been identified as promising novel approaches not requiring DHCA, as have the use of biomarkers to enable early diagnosis and intervention for aortic pathologies.

The Aortic Pathologies: How Far We Understand It and Its Implications on Thoracic Aortic Surgery

Thoracic aortic diseases contribute to a major part of cardiac surgeries. The severity of pathologies varies significantly from emergency and life-threatening to conservatively managed conditions. Life-threatening conditions include type A aortic dissection and rupture. Aortic aneurysm is an example of a conservatively managed condition. Pathologies that affect the arterial wall can have a profound impact on the presentation of such cases. Several risk factors have been identified that increase the risk of emergency presentations such as connective tissue disease, hypertension, and vasculitis. The understanding of aortic pathologies is essential to improve management and clinical outcomes.

Nomogram to differentiate between aortic dissection and non-ST segment elevation acute coronary syndrome: a retrospective cohort study

Background

Aortic dissection (AD) and non-ST segment elevation acute coronary syndrome (ACS) are two of the most life-threatening diseases encountered in the emergency department (ED), but there are no rapid and reliable tools for differentiation. The purpose of this study is to develop and validate a nomogram that incorporates both the clinical characteristics and bedside laboratory tests available to differentiate between AD and non-ST segment elevation ACS (NSTE-ACS).

Methods

Between January 2016 and July 2018, patients with AD and NSTE-ACS were enrolled and divided into training and validation groups. The least absolute shrinkage and selection operator (LASSO) regression model was used to select the factors with significant value of predicting the diagnosis of AD. A nomogram was built on the basis of multivariable logistic regression analysis. Area under the curve (AUC) of receiver operating characteristic (ROC) curve and the calibration curve were used to assess the performance of the nomogram. Decision curve analysis was performed to assess the clinical utility of the nomogram.

Results

A final cohort of 263 patients (94 patients with AD and 169 patients with NSTE-ACS) were enrolled. Six variables were incorporated in the nomogram: pain severity, tearing pain, pulse asymmetry, electrocardiogram (ECG), D-dimer level and troponin I level. The AUC of the nomogram to predict the probability of AD was 0.919 (95% CI, 0.876-0.962) in the training group and 0.938 (95% CI, 0.888-0.989) in the validation group. The calibration curve demonstrated a good consistency between the actual clinical results and the predicted outcomes. The decision curve analysis indicated that the nomogram had higher overall net benefits in predicting AD in both the training group and the validation group.

Conclusions

We developed and validated a predictive nomogram that could be used as a tool to differentiate AD from NSTE-ACS rapidly and accurately.

Current Controversies in Large-Vessel Inflammatory Vasculitis and Thoracic Aortic Aneurysm Disease

Large-vessel vasculitis encompasses the spectrum of vasculitides, which pathologically cause chronic granulomatous inflammatory changes, primarily in the aorta and its major branches. These patients are at risk of developing life-threatening aortic lesions that, without recognition and prompt treatment, can cause detrimental effects. Many provocative issues surrounding large-vessel vasculitis and its surgical treatment still remain, spanning from recognition to management. In this review, we discuss the main large-vessel vasculitides, Takayasu's arteritis and giant cell arteritis. We include the key points and current controversies surrounding diagnostic imaging, timing of interventions, and patient outcomes.

The genetics and biomechanics of thoracic aortic diseases

Thoracic aortic aneurysms and aortic dissections (TAAD) are highly fatal emergencies within cardiothoracic surgery. With increasing age, thoracic aneurysms become more prevalent and pose an even greater threat when they develop into aortic dissections. Both diseases are multifactorial and are influenced by a multitude of physiological and biomechanical processes. Structural stability of aorta can be disrupted by genes, such as those for extracellular matrix and contractile protein, as well as telomere dysfunction, which leads to senescence of smooth muscle and endothelial cells. Biomechanical changes such as increased luminal pressure imposed by hypertension are also very prevalent and lead to structural instability. Furthermore, ageing is associated with a pro-inflammatory state that exacerbates degeneration of vessel wall, facilitating the development of both aortic aneurysms and aortic dissection. This literature review provides an overview of the aetiology and pathophysiology of both thoracic aneurysms and aortic dissections. With an improved understanding, new therapeutic targets may eventually be identified to facilitate treatment and prevention of these diseases.

Network-based analysis reveals novel gene signatures in the peripheral blood of patients with sporadic nonsyndromic thoracic aortic aneurysm

Thoracic aortic aneurysm (TAA), a serious cardiovascular disease that causes morbidity and mortality worldwide. At present, few biomarkers can accurately diagnose the appearance of TAA before dissection or rupture. Our research has the intention to investigate the developing applicable biomarkers for TAA promising clinically diagnostic biomarkers or probable regulatory targets for TAA. In our research, we built correlation networks utilizing the expression profile of peripheral blood mononuclear cell obtained from a public microarray data set (GSE9106). Furthermore, we chose the turquoise module, which has the strongest significance with TAA and was further analyzed. Fourteen genes that overlapped with differentially expressed proteins in the medial aortic layer were obtained. Subsequently, we verified the results applying quantitative polymerase chain reaction (Q-PCR) to our clinical specimen. In general, the Q-PCR results coincide with the majority of the expression profile. Fascinatingly, a notable change occurred in CLU, DES, MYH10, and FBLN5. In summary, using weighted gene coexpression analysis, our study indicates that CLU, DES, MYH10, and FBLN5 were identified and validated to be related to TAA and might be candidate biomarkers or therapeutic targets for TAA.

Size and dissection: what is the relation?

Thoracic aortic aneurysm is a complex disease. The consequences of such silent and indolent disease include acute aortic syndrome if not recognized early and treated appropriately. Aortic aneurysm size was a reliable clinical marker to aid clinical intervention; however, aneurysm growth is variable and is influenced by many factors such as age, presence of connective tissue disorders, genetic disorders, hypertension, inflammatory conditions of the aorta, autoimmune diseases, smoking, and history of previous cardiac surgery. Therefore, aortic size became a non-specific disease surrogate and prediction tool on outcome and intervention. In this review article, we examined the current literature for evidence about aneurysm size and its relation to type A aortic dissection.

Role of Thrombospondin-1 in Mechanotransduction and Development of Thoracic Aortic Aneurysm in Mouse and Humans

RATIONALE

Abnormal mechanosensing of smooth muscle cells (SMCs) resulting from the defective elastin-contractile units has been suggested to drive the formation of thoracic aortic aneurysms; however, the precise molecular mechanism has not been elucidated.

OBJECTIVE

The aim of this study was to identify the crucial mediator(s) involved in abnormal mechanosensing and propagation of biochemical signals during the aneurysm formation and to establish a basis for a novel therapeutic strategy.

METHODS AND RESULTS

We used a mouse model of postnatal ascending aortic aneurysms ( Fbln4SMKO; termed SMKO [SMC-specific knockout]), in which deletion of Fbln4 (fibulin-4) leads to disruption of the elastin-contractile units caused by a loss of elastic lamina-SMC connections. In this mouse, upregulation of Egr1 (early growth response 1) and angiotensin-converting enzyme leads to activation of Ang II (angiotensin II) signaling. Here, we showed that the matricellular protein, Thbs1 (thrombospondin-1), was highly upregulated in SMKO ascending aortas and in human thoracic aortic aneurysms. Thbs1 was induced by mechanical stretch and Ang II in SMCs, for which Egr1 was required, and reduction of Fbln4 sensitized the cells to these stimuli and led to higher expression of Egr1 and Thbs1. Deletion of Thbs1 in SMKO mice prevented the aneurysm formation in ≈80% of DKO (SMKO;Thbs1 knockout) animals and suppressed Ssh1 (slingshot-1) and cofilin dephosphorylation, leading to the formation of normal actin filaments. Furthermore, elastic lamina-SMC connections were restored in DKO aortas, and mechanical testing showed that structural and material properties of DKO aortas were markedly improved.

CONCLUSIONS

Thbs1 is a critical component of mechanotransduction, as well as a modulator of elastic fiber organization. Maladaptive upregulation of Thbs1 results in disruption of elastin-contractile units and dysregulation of actin cytoskeletal remodeling, contributing to the development of ascending aortic aneurysms in vivo. Thbs1 may serve as a potential therapeutic target for treating thoracic aortic aneurysms.