Biomarkers in TAA-the Holy Grail

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.

Histopathological findings of diseased ascending aortae with clinicopathological correlation - A single-centre study of 160 cases

The most common reason for ascending aorta resection is an aneurysm or dissection. Aortic dissection is a life-threatening condition in which an aneurysm is a crucial risk factor. The essential criteria for aneurysm resection include the diameter, genetic predisposition, and aortic valve disease. This study aimed to compare the histological findings in aneurysms and dissections and correlate them with clinical parameters to determine whether histopathological findings correspond with the current clinical approach. A total of 160 ascending aorta surgical specimens, separate or with an aortic valve, were collected and divided into four groups: aneurysm-tricuspid (n = 40; median 67 y), aneurysm-malformed (n = 68; median 50 y), dissection-tricuspid (n = 48; median 65.5 y), and dissection-malformed (n = 4; median 52.5 y). Male preponderance was observed in all groups; the youngest patients were in the aneurysm-malformed group. None of the specimens showed normal aortic histology. The most common finding in the aortic samples was medial degeneration, which was the most severe and most common in dissection. The mildest findings were found in the aneurysm-malformed group. Atherosclerosis was predominant and most severe in the aneurysm-tricuspid group, while only mild in both dissection groups, suggesting its protective effect against this complication. Chronic aortitis was the least common pathology, found only in the aneurysm-tricuspid group. The aortic valve was resected and examined simultaneously with the ascending aorta in 76 cases, most commonly in the aneurysm-malformed group (n = 53). Myxoid degeneration was the major finding in the tricuspid aortic valves, with calcifications in the malformed. Comparing the histopathological results with the clinical aspects, aneurysms with a malformed aortic valve seem to be managed appropriately, with the findings not reaching the severity as in patients with a tricuspid valve. In contrast, in patients with a tricuspid valve, there were more dissections than aneurysms, with a significant subset of aneurysms showing histological findings almost identical to those of dissections. Supported by histological findings, patients with a diseased ascending aorta and tricuspid aortic valve represent an underdiagnosed risk group that would benefit from earlier diagnosis and intervention to prevent dissection. There is a need to find a marker for dissection risk other than the aortic diameter.

Targeted Proteomic Analysis of Patients with Ascending Thoracic Aortic Aneurysm

BACKGROUND

There is a need for clinical markers to aid in the detection of individuals at risk of harboring an ascending thoracic aneurysm (ATAA) or developing one in the future.

OBJECTIVES

To our knowledge, ATAA remains without a specific biomarker. This study aims to identify potential biomarkers for ATAA using targeted proteomic analysis.

METHODS

In this study, 52 patients were divided into three groups depending on their ascending aorta diameter: 4.0-4.5 cm (N = 23), 4.6-5.0 cm (N = 20), and >5.0 cm (N = 9). A total of 30 controls were in-house populations ethnically matched to cases without known or visible ATAA-related symptoms and with no ATAA familial history. Before the debut of our study, all patients provided medical history and underwent physical examination. Diagnosis was confirmed by echocardiography and angio-computed tomography (CT) scans. Targeted-proteomic analysis was conducted to identify possible biomarkers for the diagnosis of ATAA.

RESULTS

A Kruskal-Wallis test revealed that C-C motif chemokine ligand 5 (CCL5), defensin beta 1 (HBD1), intracellular adhesion molecule-1 (ICAM1), interleukin-8 (IL8), tumor necrosis factor alpha (TNFα) and transforming growth factor-beta 1 (TGFB1) expressions are significantly increased in ATAA patients in comparison to control subjects with physiological aorta diameter (p < 0.0001). The receiver-operating characteristic analysis showed that the area under the curve values for CCL5 (0.84), HBD1 (0.83) and ICAM1 (0.83) were superior to that of the other analyzed proteins.

CONCLUSIONS

CCL5, HBD1 and ICAM1 are very promising biomarkers with satisfying sensitivity and specificity that could be helpful in stratifying risk for the development of ATAA. These biomarkers may assist in the diagnosis and follow-up of patients at risk of developing ATAA. This retrospective study is very encouraging; however, further in-depth studies may be worthwhile to investigate the role of these biomarkers in the pathogenesis of ATAA.

Tracking an Elusive Killer: State of the Art of Molecular-Genetic Knowledge and Laboratory Role in Diagnosis and Risk Stratification of Thoracic Aortic Aneurysm and Dissection

The main challenge in diagnosing and managing thoracic aortic aneurysm and dissection (TAA/D) is represented by the early detection of a disease that is both deadly and “elusive”, as it generally grows asymptomatically prior to rupture, leading to death in the majority of cases. Gender differences exist in aortic dissection in terms of incidence and treatment options. Efforts have been made to identify biomarkers that may help in early diagnosis and in detecting those patients at a higher risk of developing life-threatening complications. As soon as the hereditability of the TAA/D was demonstrated, several genetic factors were found to be associated with both the syndromic and non-syndromic forms of the disease, and they currently play a role in patient diagnosis/prognosis and management-guidance purposes. Likewise, circulating biomarker could represent a valuable resource in assisting the diagnosis, and several studies have attempted to identify specific molecules that may help with risk stratification outside the emergency department. Even if promising, those data lack specificity/sensitivity, and, in most cases, they need more testing before entering the “clinical arena”. This review summarizes the state of the art of the laboratory in TAA/D diagnostics, with particular reference to the current and future role of molecular-genetic testing.

Risk profile analysis of uncomplicated type B aortic dissection patients undergoing thoracic endovascular aortic repair: Laboratory and radiographic predictors

BACKGROUND

There is emerging evidence to support pre-emptive thoracic endovascular aortic repair (TEVAR) intervention for uncomplicated type B aortic dissection (unTBAD). Pre-emptive intervention would be particularly beneficial in patients that have a higher baseline risk of progressing to complicated TBAD (coTBAD). There remain debate on the optimal clinical, laboratory, morphological, and radiological parameters, which would identify the highest-risk patients that would benefit most from pre-emptive TEVAR.

AIM

This review summarizes evidence on the clinical, laboratory, and morphological parameters that increase the risk profiles of unTBAD patients.

METHODS

A comprehensive literature search was carried out on multiple electronic databases including PubMed, EMBASE, Ovid, and Scopus to collate all research evidence on the clinical, laboratory, and morphological parameters that increase the risk profiles of unTBAD patients RESULTS: At present, there are no clear clinical guidelines using risk-stratification to inform the selection of unTBAD patients for TEVAR. However, there are noticeable literature trends that can assist with the identification of the most at-risk unTBAD patients. Patients are at particular risk when they have refractory pain and/or hypertension, elevated C-reactive protein (CRP), larger aortic diameter, and larger entry tears. These risks should be considered alongside factors that increase the procedural risk of TEVAR to create a well-balanced approach. Advances in biomarkers and imaging are likely to identify more pertinent parameters in the future to optimize the development of balanced, risk-stratified treatment protocols.

CONCLUSION

There are a variety of risk profiling parameters that can be used to identify the high-risk unTBAD patient, with novel biomarkers and imaging parameters emerging. Longer-term evidence verifying these parameters would be ideal. Further randomized controlled trials and multicentre registry analyses are also warranted to guide risk-stratified selection protocols.

Aortic gene dictionary in the precision medicine era—update from the Aortic Institute at Yale New Haven

This paper reviews the current understanding of the inherited, genetic nature of thoracic aortic aneurysm and dissection (TAAD), as well as the practice of genetic testing for thoracic aortic disease at the Aortic Institute at Yale-New Haven Hospital.

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.

Long Noncoding RNAs CARMN, LUCAT1, SMILR, and MALAT1 in Thoracic Aortic Aneurysm: Validation of Biomarkers in Clinical Samples

Materials and Methods

Relative expression of lncRNAs CARMN, LUCAT1, SMILR, and MALAT1 was tested in clinical aortic tissue and blood plasma samples from TAA and non-TAA patients using the qRT-PCR method. The Mann–Whitney U test was used to compare ΔCt values between the study groups. ROC curve analysis was performed to evaluate the diagnostic value of plasma lncRNAs.

Results

We found significantly reduced CARMN (p = 0.033) and LUCAT1 (p = 0.009) expression in aortic tissue samples from TAA patients. Relative expression of MALAT1 (p = 0.117) and SMILR (p = 0.610) did not differ in aortic tissue between the TAA and non-TAA groups. Expression of both LUCAT1 and SMILR was significantly decreased in TAA patients' blood plasma compared to controls (p = 0.018 and p = 0.032, respectively). However, only LUCAT1 showed the ability to discriminate aneurysmal disease in patients' blood plasma (AUC = 0.654, 95%CI = 0.534‐0.775, p = 0.018).

Conclusions

We have shown that the expression of lncRNAs CARMN and LUCAT1 is reduced in dilated aortic tissue and that the LUCAT1 and SMILR expression is lower in the blood plasma of TAA patients. Decreased LUCAT1 expression in TAA patients' blood plasma may have diagnostic potential in discriminating patients with TAA.

Asymmetric Dimethylarginine in Patients with Ascending Aortic Aneurysms

BACKGROUND

Ascending thoracic aortic aneurysm (aTAA) is a heterogeneous group of disorders that involve impaired endothelial function. The nitric oxide (NO) synthase inhibitor asymmetric dimethylarginine (ADMA) serves as an endothelial dysfunction marker. Thus, we investigated ADMA levels in patients with aTAA.

METHODS

Eighty-six patients with aTAA and 18 healthy individuals were enrolled. All patients underwent echocardiography. Plasma ADMA levels were measured using high-performance liquid chromatography.

RESULTS

ADMA levels were higher in aTAA patients than in control patients (p = 0.034). According to the multivariable regression model, higher ADMA levels were associated with ascending aortic diameter (p = 0.017), smoking (p = 0.016), and log-transformed estimated glomerular filtration rate (eGFR, p = 0.005).

CONCLUSION

This pilot study demonstrates an association of ADMA with ascending aortic dilatation; however, further studies are needed to investigate whether increased ADMA levels underlie aTAA development.

Guilt by association: a paradigm for detection of silent aortic disease

Detection of clinically silent thoracic aortic aneurysm (TAA) is challenging due to the lack of symptoms (until aortic rupture or dissection occurs). A large proportion of TAA are identified incidentally while imaging a patient for other reasons. However, recently several clinical "associates" of TAA have been described that can aid in identification of silent TAA. These "associates" include intracranial aneurysm, aortic arch anomalies, abdominal aortic aneurysm (AAA), simple renal cysts (SRC), bicuspid aortic valve, temporal arteritis, a positive family history of aneurysm disease, and a positive thumb-palm sign. In this article we examine these associates of TAA and the data supporting their involvement with asymptomatic TAA.

Paradigm for Detecting Silent Thoracic Aneurysm Disease

Thoracic aortic aneurysms (TAA) pose a serious detection challenge owing to their clinically silent nature. Only a small fraction of TAAs cause symptoms in patients. However, the mortality burden of this disease in the population is significant, given the high lethality of such complications as aortic rupture and dissection. Widespread screening for TAA has not been shown to be cost-effective. Therefore, currently most patients with a TAA are identified incidentally during an imaging study conducted for other reasons. Once a TAA diagnosis is established, prophylactic surgical treatment can safely be performed for aneurysms of the ascending aorta, aortic arch, and descending or thoracoabdominal aorta, thus preventing aneurysm-related death. To facilitate early detection of TAA, recent studies have identified several "associates" of TAA that may be useful in making a timely diagnosis. These "associates" include intracranial aneurysm, aortic arch anomalies, abdominal aortic aneurysm, simple renal cysts, bicuspid aortic valve, temporal arteritis, a positive family history of aneurysm disease, and a positive thumb-palm sign, among others. Although for many of these "associates" the underlying mechanism that would explain the association remains to be elucidated, the clinical correlation is strong enough to suggest screening patients with these findings for TAA. This article introduces the "Guilt by Association" paradigm for detection of silent thoracic aortic disease based on detection of clinical markers associated with this condition.

Screening for aortic aneurysms in patients with coronary artery disease: should it be done?

Aneurysmal dilation of the aorta is a clinically silent disease that often presents first with a catastrophic event. As a result, several clinician societies and organizations have recommended screening to detect aneurysms before they rupture. Although screening may reduce mortality, the implementation of screening has been poor. Cardiologists are uniquely positioned to improve this gap as they handle patients with typical risk factors for aneurysmal diseases of the aorta and can endorse and implement screening in a high-risk population. The following article attempts to concisely give a navigational tool to the cardiovascular specialist for her/his role in the diagnosis and management of thoracic and abdominal aortic aneurysms, citing evidence as well as stating opinions on how to improve outcomes in this unique patient population.

Guilt by association: paradigm for detecting a silent killer (thoracic aortic aneurysm)

Recent studies have confirmed a close association between various medical conditions (intracranial aneurysm, abdominal aortic aneurysm, temporal arteritis, autoimmune disorder, renal cysts), certain aortic anatomic variants (bovine aortic arch, direct origin of left vertebral artery from aortic arch, bicuspid aortic valve), and family history of aneurysm disease with thoracic aortic aneurysm and dissection. This paper reviews these associations. We propose to capitalise on these associations as powerful and expanding opportunities to diagnose the virulent but silent disease of thoracic aortic aneurysm. This can be accomplished by recognition of this 'guilt by association' with the other conditions. Thus, patients with associated diseases and anatomic variants should be investigated for silent aortic aneurysms. Such a paradigm holds substantial potential for reducing death from the silent killer represented by thoracic aortic aneurysm disease.

Total serum transforming growth factor-β1 is elevated in the entire spectrum of genetic aortic syndromes

BACKGROUND

Total serum transforming growth factor-beta 1 (tsTGF-β1) is increased in patients with Marfan syndrome (MFS), but it has not been assessed in thoracic aortic aneurysm and dissection (TAAD), Loeys-Dietz syndrome (LDS), and bicuspid aortic valve disease (BAVD).

HYPOTHESIS

tsTGF-β1 is increased in genetic aortic syndromes including TAAD, LDS, MFS, and BAVD.

METHODS

We measured tsTGF-β1 and performed sequencing of the genes FBN1, TGFBR1, and TGFBR2 in 317 consecutive patients with suspected or known genetic aortic syndrome (167 men, 150 women; mean age 43 ± 14 years). TAAD was diagnosed in 20, LDS in 20, MFS in 128, and BAVD in 30 patients, and genetic aortic syndrome was excluded in 119 patients.

RESULTS

Elevated tsTGF-β1 levels were associated with causative gene mutations (P = 0.008), genetic aortic syndrome (P = 0.009), and sporadic occurrence of genetic aortic syndrome (P = 0.048), whereas only genetic aortic syndrome qualified as an independent predictor of tsTGF-β1 (P = 0.001). The tsTGF-β1 levels were elevated in FBN1 and NOTCH1 mutations vs patients without mutations (both P = 0.004), and in NOTCH1 mutations vs ACTA2/MYH11 mutations (P = 0.015). Similarly, tsTGF-β1 levels were elevated in MFS (P = 0.003) and in BAVD (P = 0.006) vs patients without genetic aortic syndrome. In contrast to specific clinical features of MFS, FBN1 in-frame mutations (P = 0.019) were associated with increased tsTGF-β1 levels.

CONCLUSIONS

tsTGF-β1 is elevated in the entire spectrum of genetic aortic syndromes. However, gradual differences in the increases of tsTGF-β1 levels may mirror different degrees of alteration of tsTGF-β1 signaling in different genetic aortic syndromes.

Biomarkers for the diagnosis of aortic dissection

This review discusses the role of biomarkers for both diagnoses and disease monitoring before, during, and after treatment of aortic dissection.

Predicting aortic enlargement in type B aortic dissection

Patients with uncomplicated acute type B aortic dissection (ABAD) can generally be treated with conservative medical management. However, these patients may develop aortic enlargement during follow-up, with the risk of rupture. Several predictors have been studied in recent years to identify ABAD patients at high risk of aortic enlargement, who may benefit from early surgical or endovascular intervention. This study reviewed and summarized the current available literature on prognostic variables related to aortic enlargement during follow-up in uncomplicated ABAD patients. It revealed multiple factors affecting aortic expansion including demographic, clinical, pharmacologic and radiologic variables. Such predictors may be used to identify those ABAD patients at higher risk for aortic enlargement who may benefit from closer radiologic surveillance or early endovascular intervention. This approach deserves even more consideration because a significant number of patients develop aneurysmal degeneration along the dissected segments during follow-up, and may lose the opportunity for endovascular treatment if not identified at an early stage.