D-dimer as a biomarker for acute aortic dissection: a systematic review and meta-analysis

A Comprehensive Exploration of Novel Biomarkers for the Early Diagnosis of Aortic Dissection

Aortic dissection (AD) is a catastrophic life-threatening cardiovascular emergency with a 1-2% per hour mortality rate post-diagnosis, characterized physiologically by the separation of aortic wall layers. AD initially presents as intense pain that can then radiate to the back, arms, neck or jaw along with neurological deficits like difficulty in speaking, and unilateral weakness in some patients. This spectrum of clinical features associated with AD is often confused with acute myocardial infarction, hence leading to a delay in AD diagnosis. Cardiac and vascular biomarkers are structural proteins and microRNAs circulating in the bloodstream that correlate to tissue damage and their levels become detectable even before symptom onset. Timely diagnosis of AD using biomarkers, in combination with advanced imaging diagnostics, will significantly improve prognosis by allowing earlier vascular interventions. This comprehensive review aims to investigate emerging biomarkers in the diagnosis of AD, as well as provide future directives for creating advanced diagnostic tools and imaging techniques.

Diagnostic Accuracy of D-Dimer for Acute Aortic Syndromes: Systematic Review and Meta-Analysis

STUDY OBJECTIVE

Acute aortic syndrome is a life-threatening emergency condition. Previous systematic reviews of D-dimer diagnostic accuracy for acute aortic syndrome have been contradictory and based on limited data, but recently published studies offer potential for a more definitive overview. We aimed to perform a systematic review and meta-analysis to determine the diagnostic accuracy of D-dimer for diagnosing acute aortic syndrome.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Library from inception to February 2024. Additionally, the reference lists of included studies and other systematic reviews were thoroughly searched. All diagnostic cohort studies (prospective or retrospective) that assessed the use of D-dimer for diagnosing acute aortic syndrome compared with a reference standard test (eg, computed tomographic angiography (CTA), ECG-gated CTA, echocardiography, magnetic resonance angiography, operation, or autopsy) were included. Two independent reviewers completed study selection, data extractions and quality assessment using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Data were synthesized using a bivariate meta-analysis model.

RESULTS

Of 2017 potentially relevant citations, 25 cohort studies met the inclusion criteria, and 18 reporting the 500 ng/mL threshold were included in the primary meta-analysis. Risk of bias domains were mostly unclear due to limited study reporting. The summary sensitivity was 96.5% (95% credible interval [CrI] 94.8% to 98%) and summary specificity was 56.2% (95% CrI, 48.3% to 63.9%). Study specificity varied markedly from 33% to 86%, indicating substantial heterogeneity. Sensitivity analysis including the 7 studies reporting other thresholds showed summary sensitivity of 95.7% (95% CrI, 93.2% to 97.5%) and summary specificity of 57.5% (95% CrI, 50.1% to 64.6%).

CONCLUSION

D-dimer concentration has high sensitivity (96.5%) and moderate specificity (56.2%) for acute aortic syndrome, with some uncertainty around estimates due to risk of bias and heterogeneity. Previous meta-analysis reporting higher specificity may be explained by inclusion of case-control studies that may overestimate accuracy.

Elevation of D-dimer in eosinophilic gastrointestinal diseases in the absence of venous thrombosis: A case series and literature review

Introduction

Eosinophilic gastrointestinal diseases (EGIDs) are rare and heterogeneous diseases characterized by excessive eosinophilic infiltration of the digestive system. D-dimer levels and its possible association with disease course were not reported.

Case series

We reported a series of three EGID cases presenting with high levels of D-dimer. No evidence for potential venous thromboembolism was found through computed tomography pulmonary angiogram and vascular ultrasounds. Moreover, D-dimer levels decreased after short-time systemic prednisolone administration, accompanied by remission of clinical symptoms and decrease of peripheral eosinophil counts and IgE levels.

Conclusion

Elevation of D-dimer in EGID may not represent thrombotic events but is possibly associated with disease severity. More population-based studies are needed to delineate the potential relationship among D-dimer, thrombosis, and inflammation in EGID.

Initial Triage and Management of Patients with Acute Aortic Syndromes

The acute aortic syndromes (AAS) are life-threatening vascular compromises within the aortic wall. These include aortic dissection (AD), intramural hematoma (IMH), penetrating aortic ulcer (PAU), and blunt traumatic thoracic aortic injury (BTTAI). While patients classically present with chest pain, the presentation may be highly variable. Timely diagnosis is critical to initiate definitive treatment and maximize chances of survival. In high-risk patients, treatment should begin immediately, even while diagnostic evaluation proceeds. The mainstay of medical therapy is acute reduction of heart rate and blood pressure. Surgical intervention is often required but is informed by patient anatomy and extent of vascular compromise.

How we manage a high D-dimer

D-dimer, a soluble fibrin degradation product that originates from plasmin-induced degradation of cross-linked fibrin, is an important biomarker of coagulation activation and secondary fibrinolysis that is routinely used to rule out venous thromboembolism (VTE), and to evaluate the risk of VTE recurrence, as well as the optimal duration of anticoagulant therapy. Besides VTE, D-dimer may be high due to physiologic conditions, including aging, pregnancy, and strenuous physical activity. In addition, several disorders have been associated with increased D-dimer levels, ranging from disseminated intravascular coagulation to infectious diseases and cancers. Thus, it is far from unusual for hematologists to have to deal with ambulatory individuals with increased D-dimer without signs or symptoms of thrombus formation. This narrative review is dedicated to the management of these cases by the hematologist.

Analysis of clinical characteristics and imagological features of the aortic dissection patients with negative D-dimer results

Background

D-dimer (DD) is a vital biomarker to rule out the diagnosis of aortic dissection (AD). However, the DD level in some patients with AD is not high in clinical practice, which often leads to missed diagnosis; therefore, understanding the characteristics of patients with AD and negative DD is of great clinical value.

Methods

From May 2015 to October 2020, 286 patients with AD who visited the first medical contact (FMC) within 24 h of symptom onset and were hospitalized in the Xiamen Cardiovascular Hospital of Xiamen University were enrolled in this study. Clinical characteristics and outcomes of patients were assessed.

Results

Among them, 13 cases (approximately 4.5%) had negative DD results. Compared to patients with positive DD results, patients with negative DD results had significantly higher platelet counts and lower aortic dissection detection risk scores (ADD-RS). The imagological analysis showed that patients with AD and negative DD had lower extension scores and milder damage to the mesenteric artery and three branches of the aortic arch. Furthermore, the results of the multivariable analysis showed that white blood cell count (WBC) [odds ratio (OR): 1.379, P = 0.028], FMC (OR: 0.904, P = 0.028), and extension score (OR: 1.623, P = 0.046) were associated with negative DD result.

Conclusions

Patients with AD and negative DD results had longer FMC and lower WBC. Imaging showed a smaller tear extension range and less damage to the mesenteric artery and three branches of the aortic arch. A negative DD result could not completely rule out AD even if the ADD-RS was zero.

Aortic Dissection Detection Risk Score and D-Dimer for Acute Aortic Syndromes in the Chinese Population: Exploration of Optimal Thresholds and Integrated Diagnostic Value

This study aimed to assess the diagnostic performance of the aortic dissection detection risk score (ADD-RS) plus D-dimer for acute aortic syndrome (AAS) in Chinese patients. Two hundred and sixty-two and 200 patients with suspected AAS symptoms were enrolled as exploration cohort and validation cohort, respectively. In exploration cohort, ADD-RS plus D-dimer (AUC = 0.929, 95%CI: 0.887-0.971) presented a better diagnostic value for AAS than ADD-RS or D-dimer alone. Meanwhile, ADD-RS > 1 and D-dimer > 2000 ng/mL were the optimal thresholds. Then, a diagnostic model integrating ADD-RS > 1 plus D-dimer > 2000 ng/mL was established, presenting sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 92.5%, 70.3%, 34.9%, and 98.2%, respectively. In validation cohort, the established diagnostic model exhibited a sensitivity, specificity, PPV, and NPV of 93.1%, 70.2%, 34.6%, and 98.4%, respectively, for diagnosing AAS. Summarily, ADD-RS > 1 and D-dimer > 2000 ng/mL are optimal thresholds for diagnosing AAS in the Chinese population. However, confirmative MSCT results are necessary.

Analysis of Short-Term Clinical Outcomes and Influencing Factors in Patients with Acute Type B Aortic Intramural Hematoma Treated with Optimal Medical Therapy

This study aimed to investigate the short-term predictors of aortic-related adverse events in patients with acute type B aortic intramural hematoma (IMH) initially treated with optimized medical therapy.A total of 157 patients with acute type B IMH were included in this study. These patients were divided into worsening group (n = 45) and stable group (n = 112) based on the incidence of aortic-related adverse events. The clinical data and imaging features of the two groups were compared. Multivariate logistic regression analysis of predictors of aortic-related adverse events in type B IMH was performed. Receiver operating characteristic (ROC) curve was applied to determine the optimal cutoff value for maximum descending aorta diameter (MDAD). Kaplan-Meier survival curve was used to analyze the incidence of aortic-related adverse events.Worsening and stable groups were statistically significant in diuretics, abnormal D-dimer level, observation endpoint systolic blood pressure (SBP), MDAD, aortic atherosclerosis, ulcer-like projection (ULP), and thickness of hematoma (P < 0.05). Multivariate logistic regression showed that abnormal D-dimer level (OR = 12.464, P = 0.025), MDAD (OR = 1.113, P = 0.030), and ULP (OR = 5.849, P = 0.022) were powerful independent risk factors for predicting aortic-related adverse events in type B IMH, and observation endpoint SBP within 100-120 mmHg (OR = 0.225, P = 0.014) was a protective factor for predicting aortic-related adverse events in type B IMH. The cutoff value of MDAD was 35.2 mm.Short-term imaging is recommended for type B IMH patients with abnormal D-dimer level, MDAD > 35.2 mm, and ULP. Blood pressure should also be strictly monitored and controlled during the acute phase of IMH.

Outpatient management of patients after surgical operations for acute aortic dissection of type A

Acute aortic dissection of type A is still one of the most difficult diseases faced by doctors of all specialties. The current review is based on an analysis of current literature data and clinical guidelines. It covers various aspects of outpatient patient management and focuses on conservative therapy. The lack of an adequate diagnostic algorithm often leads to complications and, ultimately, death. The dynamic nature of the disease, the variability of clinical manifestations and the course of the pathological process require special attention. Both short-term and long-term survival of the patient depends on careful observation. Postoperative management of patients with acute aortic dissection of type A is entirely entrusted to the outpatient unit, which, due to the absence of the main aspects of the strategy in modern clinical recommendations, is not always prepared for the curation of this complex cohort of patients. The lack of experience in managing this pathology by outpatient hospital doctors causes significant difficulties in interpreting instrumental diagnostic methods, which leads to further erroneous tactics with the development of long-term complications. Due to the lack of a unified scheme of drug therapy, the question of prescribing drugs in these patients, who often receive a fairly large range of medications for concomitant pathology, remains open. These factors contribute to polyprogmasia or vice versa – insufficient volume of drug therapy, which further leads to the progression of the disease. As a result of insufficient emphasis on the basics of outpatient management of this cohort of patients, a whole complex of problems arises, leading to unsatisfactory treatment results and increased healthcare costs for their subsequent solution. The purpose of the review is to highlight the main problems of this issue from the point of view of evidence-based medicine.

D-dimer in Marfan syndrome: effect of obstructive sleep apnea induced blood pressure surges

Aortic dissection and rupture are the major causes of premature death in persons with Marfan syndrome (MFS), a rare genetic disorder featuring cardiovascular, skeletal, and ocular impairments. We and others have found that obstructive sleep apnea (OSA) confers significant vascular stress in this population and may accelerate aortic disease progression. We hypothesized that D-dimer, a diagnostic biomarker for several types of vascular injury that is also elevated in persons with MFS with aortic enlargement, may be sensitive to cardiovascular stresses caused by OSA. To test this concept, we recruited 16 persons with MFS without aortic dissection and randomized them to two nights of polysomnography, without (baseline) and with OSA treatment: continuous positive airway pressure (CPAP). In addition to scoring OSA by the apnea-hypopnea index (AHI), beat-by-beat systolic BP (SBP) and pulse-pressure (PP) fluctuations were quantified. Morning blood samples were also assayed for D-dimer levels. In this cohort (male:female, 10:6; age, 36 ± 13 yr; aortic diameter, 4 ± 1 cm), CPAP eliminated OSA (AHI: 20 ± 17 vs. 3 ± 2 events/h, P = 0.001) and decreased fluctuations in SBP (13 ± 4 vs. 9 ± 3 mmHg, P = 0.011) and PP (7 ± 2 vs. 5 ± 2 mmHg, P = 0.013). CPAP also reduced D-dimer levels from 1,108 ± 656 to 882 ± 532 ng/mL (P = 0.023). Linear regression revealed a positive association between the maximum PP during OSA and D-dimer in both the unadjusted (r = 0.523, P = 0.038) and a model adjusted for contemporaneous aortic root diameter (r = 0.733, P = 0.028). Our study revealed that overnight CPAP reduces D-dimer levels commensurate with the elimination of OSA and concomitant hemodynamic fluctuations. Morning D-dimer measurements together with OSA screening might serve as predictors of vascular injury in MFS.NEW & NOTEWORTHY What is New? Surges in blood pressure caused by obstructive sleep apnea during sleep increase vascular stress and D-dimer levels in Marfan syndrome. Elevations in D-dimer can be lowered with CPAP. What is Noteworthy? D-dimer levels might serve as a marker for determining the significance of obstructive sleep apnea in persons with Marfan syndrome. D-dimer or obstructive sleep apnea screening is a potential method to identify persons with Marfan syndrome at risk for adverse cardiovascular events.

Significant Prediction of In-hospital Major Adverse Events by D-Dimer Level in Patients With Acute Type A Aortic Dissection

Background

Acute type A aortic dissection (ATAAD) is a rare, life-threatening condition affecting the aorta. This study explores the relationship between the level of admission D-dimer, which was assessed during the first 2 h from admission, and in-hospital major adverse events (MAE) with ATAAD.

Methods

A total of 470 patients with enhanced computed tomography (CT) confirmed diagnosis of ATAAD who underwent operation treatment in Guangdong Provincial People's hospital between September 2017 and June 2021 were enrolled in the present study. The X-tile program was used to determine the optimal D-dimer thresholds for risk. Restricted cubic spline (RSC) was performed to assess the association between D-dimer and endpoint. The perioperative data were compared between the two groups, univariate and multivariate analyses were used to investigate the risk factors of major adverse events (in-hospital mortality, gastrointestinal bleeding, paraplegia, acute kidney failure, reopen the chest, low cardiac output syndrome, cerebrovascular accident, respiratory insufficiency, MODS, gastrointestinal bleeding, and severe infection).

Results

Among 470 patients, 151 (32.1%) had MAE. In-hospital mortality was 7.44%. The patients with D-dimer >14,500 ng/ml were more likely to present with acute kidney failure, low cardiac output, cerebrovascular accident, multiple organ dysfunction syndromes (MODS), gastrointestinal bleeding, and severe infection. D-dimer level was an independent risk factor for acute kidney failure (OR 2.09, 95% CI: 1.25–3.51, p = 0.005), MODS (OR 6.40, 95% CI: 1.23–33.39, p = 0.028), gastrointestinal bleeding (OR 17.76, 95% CI: 1.99–158.78, p = 0.010) and mortality (OR 3.17, 95% CI: 1.32–7.63, p = 0.010). Multivariate regression analysis of adverse events also suggested that D-dimer >14,500 ng/ml (OR 1.68, 95% CI: 1.09–2.61, p = 0.020) was the independent risk factor of major adverse events.

Conclusions

Increasing D-dimer levels were independently associated with the in-hospital MAE and thus can be used as a useful prognostic biomarker before the surgery.

Relationship of acute type A aortic dissection and disseminated intravascular coagulation

OBJECTIVE

Acute type A aortic dissection (ATAAD) is a critical disease presenting with disseminated intravascular coagulation (DIC). However, the relationship between the degree of DIC and false lumen conditions remains unclear. In the present study, we evaluated the degree of preoperative DIC and the outcomes of ATAAD treatment.

METHODS

A total of 124 patients with ATAAD (70 men and 54 women) treated from January 2012 to January 2020 were included in the present study. The correlation between the preoperative Japanese Association for Acute Medicine (JAAM) DIC score and the false lumen diameter and length, measured using preoperative computed tomography, was examined retrospectively. The correlations were calculated using liner regression analysis. The level of statistical significance was set at P < .05.

RESULTS

The patients were divided into two groups: a low JAAM DIC score group and a high JAAM DIC score group. The preoperative JAAM DIC scores in the high- and low-score groups were 4.8 ± 1.2 and 1.7 ± 2.3, respectively (P < .001). The 5-year survival rates and aortic event-free rates in the low-score group were favorable compared with the high-score group; however, the differences were not statistically significant (80.8% vs 54.5%, P = .065; 63.9% vs 59.8%, P = .15, respectively). The false lumen diameter in the ascending aorta was greater in the high-score group than that in the low-score group (P < .05). The JAAM DIC score correlated significantly with the ascending false lumen diameter and the dissection length (r = 0.32 and P < .001; r = 0.29 and P = .001, respectively). A high JAAM DIC score was associated with communicating-type ATAAD (P < .05).

CONCLUSIONS

Our results suggest that high preoperative JAAM DIC scores are associated with a large false lumen and communicating-type ATAAD.

Use of coagulation-fibrinolysis markers for prognostication of Stanford type A acute aortic dissection

Purpose

Coagulation-fibrinolysis markers are widely used for the diagnosis of Stanford type A acute aortic dissection (SAAAD). However, the role of these markers in estimating prognosis remains unclear.

Methods

A single-center retrospective study was conducted to identify the relationship between preoperative D-dimer and fibrinogen levels on SAAAD postoperative early prognosis.

Results

Of 238 SAAAD patients who underwent surgery between January 2012 and December 2018, 201 (84.5%) and 37 (15.5%) patients constituted the survival and non-survival groups, respectively, 30 days after surgery. D-dimer and fibrinogen levels in the survival and non-survival groups were 45.2 ± 74.3 vs. 91.5 ± 103.6 μg/mL (p = 0.014) and 224.3 ± 95.6 vs. 179.9 ± 96.7 μg/mL (p = 0.012), respectively. According to logistic predictor analysis of 30-day mortality, significant factors showed patent type (OR 10.89, 95% CI 1.66–20.31) and malperfusion (OR 4.63, 95% CI 1.74–12.32). Increasing D-dimer (per +10 μg/mL) and decreasing fibrinogen (per −10 μg/mL) were significantly associated with patent type and malperfusion. Receiver operating characteristic analysis was performed to distinguish between survival and non-survival. The cutoff value of D-dimer was 60 μg/mL (sensitivity 61.1%; specificity 82.5%; area under curve [AUC] 0.713 ± 0.083); fibrinogen was 150 mg/dL (sensitivity 44.4%; specificity 84.0%; AUC 0.647 ± 0.092). Kaplan-Meier survival curve analysis showed that patients with D-dimer levels > 60 μg/mL and fibrinogen levels < 150 mg/dL had significantly low survival rates at 30 days after surgery (60.0%, p < 0.001).

Conclusion

Preoperative coagulation-fibrinolysis markers may be useful for predicting early prognosis in SAAAD.

Identification of Vinculin as a Potential Diagnostic Biomarker for Acute Aortic Dissection Using Label-Free Proteomics

Acute aortic dissection (AAD) is an emergent vascular disease. Currently, its diagnosis depends on clinical and radiological investigations but lacking of serum biomarkers. In this study, we aimed to identify potential serum biomarkers for AAD using label-free proteomics approach. A total of 90 serum samples were collected from three groups: patients with acute aortic dissection (AAD, n = 30), patients with acute myocardial infarction (AMI, n = 30), and healthy controls (n = 30), and the first four samples from each group were selected for label-free proteomics analysis. Using label-free approach, a total of 22 differentially expressed proteins were identified in the serum samples of the AAD group, of which 15 were upregulated and 7 were downregulated as compared to the AMI and healthy control groups. The most prominent increased protein was vinculin, which was selected to validate in total samples. The level of vinculin was significantly elevated in AAD patients (15.8 ng/ml, IQR: 9.3-19.9 ng/ml) than that in AMI patients (8.6 ng/ml, IQR:5.3-11.4 ng/ml) and healthy volunteers (5.3 ng/ml, IQR:2.8-7.6 ng/ml), P < 0.0001. Furthermore, the concentration of vinculin both increased in type A and B dissection. At the early stage of AAD, vinculin maintained a high level to 48 hours compared with that of AMI. Our study demonstrated that vinculin may play a role in the early diagnosis of AAD.

Characterization and Significance of Monocytes in Acute Stanford Type B Aortic Dissection

Acute aortic dissection (AAD) is one of the most common fatal diseases noted in vascular surgery. Human monocytes circulate in dynamic equilibrium and display a considerable heterogeneity. However, the role of monocytes in AAD remains elusive. In our recent study, we firstly obtained blood samples from 22 patients with Stanford type B AAD and 44 age-, sex-, and comorbidity-matched control subjects. And the monocyte proportions were evaluated by flow cytometry. Results showed that the percentage of total CD14⁺ monocytes in the blood samples of Stanford AAD patients was increased significantly compared with that of normal volunteers (P < 0.0005), and the absolute numbers of CD14^brightCD16⁺ and CD14^brightCD16⁻ monocytes both increased significantly regardless of the percentage of PBMC or CD14⁺ cells, while CD14^dimCD16⁺ monocytes displayed the opposite tendency. However, the percentage of CD14⁺ cells and its three subsets demonstrated no correlation with D-dimer (DD) and C-reactive protein (CRP). Then, blood mononuclear cell (PBMC) samples were collected by Ficoll density gradient centrifugation, followed with CD14⁺ magnetic bead sorting. After the purity of CD14⁺ cells was validated over 90%, AAD-related genes were concentrated in CD14⁺ monocytes. There were no significant differences observed with regard to the mRNA expression levels of MMP1 (P = 0.0946), MMP2 (P = 0.3941), MMP9 (P = 0.2919), IL-6 (P = 0.4223), and IL-10 (P = 0.3375) of the CD14⁺ monocytes in Stanford type B AAD patients compared with those of normal volunteers. The expression levels of IL-17 (P < 0.05) was higher in Stanford type B AAD patients, while the expression levels of TIMP1(P<0.05), TIMP2(P<0.01), TGF-β1 (P < 0.01), SMAD3 (P < 0.01), ACTA2 (P < 0.001), and ADAMTS-1 (P < 0.001) decreased. The data suggested that monocytes might play an important role in the development of Stanford type B AAD. Understanding of the production, differentiation, and function of monocyte subsets might dictate future therapeutic avenues for Stanford type B AAD treatment and can aid the identification of novel biomarkers or potential therapeutic targets for decreasing inflammation in AAD.

Comparative Proteomic Investigation of Plasma Reveals Novel Potential Biomarker Groups for Acute Aortic Dissection

Acute aortic dissection (AAD) is a catastrophic cardiovascular disease with high disability and mortality due to multiple fatal complications. However, the molecular changes of the serum proteome after AAD are not very clear. Here, we performed isobaric tags for relative and absolute quantitation- (iTRAQ-) based comparative proteomic analysis to investigate the proteome profile changes after AAD by collecting plasma samples from 20 AAD patients and 20 controls. Out of the 345 identified proteins, 266 were considered as high-quality quantified proteins (95%confident peptides ≥ 2), of which 25 proteins were accumulated and 12 were reduced in AAD samples. Gene ontology enrichment analysis showed that the 25 AAD-accumulated proteins were enriched in high-density lipoprotein particles for the cellular component category and protein homodimerization acidity for the molecular function category. Protein-protein interaction network analysis showed that serum amyloid A proteins (SAAs), complement component proteins, and carboxypeptidase N catalytic chain proteins (CPNs) possessed the key nodes of the network. The expression levels of six selected AAD-accumulated proteins, B2-GP1, CPN1, F9, LBP, SAA1, and SAA2, were validated by ELISA. Moreover, ROC analysis showed that the AUCs of B2-GP1 and CPN1 were 0.808 and 0.702, respectively. Our data provide insights into molecular change profiles in proteome levels after AAD and indicate that B2-GP1 and CPN1 are potential biomarkers for AAD.

Patients with markedly elevated D-dimer who do not have pulmonary embolism

OBJECTIVE

To determine the cause of a markedly raised D-dimer among patients in whom a diagnosis of pulmonary embolism (PE) has been excluded by CT pulmonary angiogram (CTPA) with particular reference to new cases of cancer and aortic dissection.

METHODS

One thousand consecutive patients, suspected of PE, who had undergone CTPA and for whom a D-dimer had been requested, were seen between 2012 and 2016. Retrospectively we examined the case records of all those in the top quintile of the D-dimer distribution whose CTPA was negative for PE. D-dimer in the top quintile ranged from 7.5 to 260 times upper limit normal.

RESULTS

Eighty-five patients fulfilled our inclusion criteria. The likely causes of their very high D-dimer were infection (n=35, 41.2%), cardiovascular disease (n=12, 14.1% including two patients with previously undiagnosed aortic dissection), surgery or trauma (n=12, 14.1%), new or active cancer (n=9, 10.6% comprising six new cancers and three patients with cancers diagnosed previously that were considered to be active) and miscellaneous causes (n=17, 20.0%). Thirty-five patients (43.5%) died over a 2-year follow-up. Kaplan-Meier survival analysis showed poorer outcomes for patients with new or active cancer, when compared with those with no known cancer (p<0.001).

CONCLUSIONS

We have shown that a small proportion of patients suspected of PE whose D-dimers are markedly elevated have diagnoses we would not want to miss including previously unsuspected cancer and aortic dissection. Further studies will be required to define the optimal workup of patients with extremely high D-dimer who do not have venous thromboembolism.

Familial Aortopathies - State of the Art Review

Aortopathies are conditions that result in aortic dilatation, aneurysm formation and dissection. Familial aortopathies (perhaps better known as heritable thoracic aortic aneurysm and dissection, h-TAAD, as not all have a positive family history) are recognised to have an underlying genetic cause and affect the aorta, predisposing it to the above pathologies. These conditions can also affect the extra-aortic vasculature, particularly large elastic arteries and other body systems. Mutations in a number of genes have been associated with h-TAAD. However, not all affected families have a pathogenic gene variant identified-highlighting the importance of a three-generational family history and the likely role of both environmental factors and future gene discoveries in furthering knowledge. Survival has improved over the last few decades, essentially due to surgical intervention. The benefit of identifying affected individuals depends upon a regular surveillance program and timely referral for surgery before complications such as dissection. Further research is required to appreciate fully the effects of individual gene variants and improve evidence for prophylactic medical therapy, as well as to understand the effect of h-TAAD on quality of life and life choices, particularly around exercise and pregnancy, for affected individuals. This will be complemented by laboratory-based research that seeks to understand the tissue pathways that underlie development of arterial pathology, ideally providing targets for novel medical therapies and a means of non-invasively identifying individuals at increased vascular risk to reduce dissection, which remains a devastating life-threatening event.

D-dimer: Preanalytical, analytical, postanalytical variables, and clinical applications

D-dimer is a soluble fibrin degradation product deriving from the plasmin-mediated degradation of cross-linked fibrin. D-dimer can hence be considered a biomarker of activation of coagulation and fibrinolysis, and it is routinely used for ruling out venous thromboembolism (VTE). D-dimer is increasingly used to assess the risk of VTE recurrence and to help define the optimal duration of anticoagulation treatment in patients with VTE, for diagnosing disseminated intravascular coagulation, and for screening medical patients at increased risk of VTE. This review is aimed at (1) revising the definition of D-dimer; (2) discussing preanalytical variables affecting the measurement of D-dimer; (3) reviewing and comparing assay performance and some postanalytical variables (e.g. different units and age-adjusted cutoffs); and (4) discussing the use of D-dimer measurement across different clinical settings.

Nursing patients with acute aortic dissection in emergency departments

Acute aortic dissection is an emergency condition that is often missed during initial assessment. Delay in diagnosis increases mortality, but the presentation can mimic several more common conditions. Emergency practitioners must maintain a high index of suspicion in patients who present with chest or back pain and ensure timely diagnostic testing and interpretation of results if aortic dissection is suspected.

Clinical Examination for Acute Aortic Dissection: A Systematic Review and Meta-analysis

OBJECTIVES

Acute aortic dissection is a life-threatening condition due to a tear in the aortic wall. It is difficult to diagnose and if missed carries a significant mortality.

METHODS

We conducted a librarian-assisted systematic review of PubMed, MEDLINE, Embase, and the Cochrane database from 1968 to July 2016. Titles and abstracts were reviewed and data were extracted by two independent reviewers (agreement measured by kappa). Studies were combined if low clinical and statistical heterogeneity (I²  < 30%). Study quality was assessed using the QUADAS-2 tool. Bivariate random effects meta analyses using Revman 5 and SAS 9.3 were performed.

RESULTS

We identified 792 records: 60 were selected for full text review, nine studies with 2,400 participants were included (QUADAS-2 low risk of bias, κ = 0.89 [for full-text review]). Prevalence of aortic dissection ranged from 21.9% to 76.1% (mean ± SD = 39.1% ± 17.1%). The clinical findings increasing probability of aortic dissection were 1) neurologic deficit (n = 3, specificity = 95%, positive likelihood ratio [LR+] = 4.4, 95% confidence interval [CI] = 3.3-5.7, I²  = 0%) and 2) hypotension (n = 4, specificity = 95%, LR+ = 2.9 95% CI = 1.8-4.6, I²  = 42%), and decreasing probability were the absence of a widened mediastinum (n = 4, sensitivity = 76%-95%, negative likelihood ratio [LR-] = 0.14-0.60, I²  = 93%) and an American Heart Association aortic dissection detection (AHA ADD) risk score < 1 (n = 1, sensitivity = 91%, LR- = 0.22, 95% CI = 0.15-0.33).

CONCLUSIONS

Suspicion for acute aortic dissection should be raised with hypotension, pulse, or neurologic deficit. Conversely, a low AHA ADD score decreases suspicion. Clinical gestalt informed by high- and low-risk features together with an absence of an alternative diagnosis should drive investigation for acute aortic dissection.

A Test in Context: D-Dimer

D-dimer is a soluble fibrin degradation product that results from ordered breakdown of thrombi by the fibrinolytic system. Numerous studies have shown that D-dimer serves as a valuable marker of activation of coagulation and fibrinolysis. Consequently, D-dimer has been extensively investigated for the diagnosis of venous thromboembolism (VTE) and is used routinely for this indication. In addition, D-dimer has been evaluated for determining the optimal duration of anticoagulation in VTE patients, for diagnosing and monitoring disseminated intravascular coagulation, and as an aid in the identification of medical patients at high risk for VTE. Thus, quantification of D-dimer levels serves an important role in guiding therapy. This review: 1) describes how D-dimer is generated; 2) reviews the assays used for its detection; and 3) discusses the role of D-dimer determination in these various conditions.

Assessing Serum Levels of ADAMTS1 and ADAMTS4 as New Biomarkers for Patients with Type A Acute Aortic Dissection

BACKGROUND Type A AAD, a serious cardiovascular emergency requiring urgent surgery, is the most common and serious AAD. The aim of this study was to investigate the diagnostic value of ADAMTS1 and ADAMTS4 in patients with type A acute aortic dissection (AAD). MATERIAL AND METHODS Immunohistochemistry and qRT-PCR were used to evaluate the protein and mRNA expression levels of ADAMTS1 and ADAMTS4 in 14 type A acute aortic dissection (AAD) tissues and 10 control aortic tissues. Serum ADAMTS1 and ADAMTS4 expression levels in 74 patients with type A AAD, 36 patients with hypertension (HPT), and 34 healthy donors were examined by ELISA. The diagnostic value of serum ADAMTS1 and ADAMTS4 were determined by receiver operator characteristic curve (ROC). Furthermore, the dynamic change of serum ADAMTS1, ADAMTS4, D-dimer, and CRP were detected before and after surgery at different time-points in 14 patients with type A AAD. RESULTS ADAMTS1 and ADAMTS4 protein and mRNA expression levels were found to be significantly higher in 14 type A AAD tissues (p<0.0001) compared with 10 control tissues. Serum ADAMTS1 and ADAMTS4 levels were significant higher in patients with type A AAD than those in the HPT and HD group (p<0.0001 for both). The AUC value, sensitivity, and specificity of ADAMTS1 were 0.9710 (95% CI: 0.9429 to 0.9991), 87.84%, and 97.06%, respectively, and those of ADAMTS4 were 0.9893 (95% CI: 0.9765 to 1.002), 94.59%, and 97.06%, respectively. In addition, serum ADAMTS4 level was gradually decreased with the time extension after surgery, similar to D-dimer change. CONCLUSIONS These data suggest that measurement of serum ADAMTS1 and ADAMTS4 levels could be potential diagnostic biomarkers for type A AAD, and ADAMTS4 might be a risk factor associated with type A AAD.

MMP-2 gene polymorphisms are associated with type A aortic dissection and aortic diameters in patients

Matrix metalloproteinases-2 (MMP-2) plays an important role in the pathogenesis of type A aortic dissection (AD). The aim of this study was to evaluate the association of 3 single nucleotide polymorphisms (SNPs) in the MMP-2 gene with type A AD risk and aortic diameters in patients. We performed a case-control study with 172 unrelated type A AD patients and 439 controls. Three SNPs rs11644561, rs11643630, and rs243865 were genotyped through the MassARRAY platform. Allelic associations of SNPs and SNP haplotypes with type A AD and aortic diameters in patients were evaluated. The frequency of the G allele of the rs11643630 polymorphism was significantly lower in type A AD patients than in control subjects (odds ratio 0.705, 95% confidence interval 0.545-0.912, P = 0.008). The association remained significant after adjusting for clinical covariates (P = 0.008). Carriers of the GG genotype of the rs11643630 polymorphism had significantly smaller aortic diameters than those with GT genotype or TT genotype (P = 0.02). Further haplotype analysis identified 1 protective haplotype (GC; P = 0.008) for development of type A AD. Again, a significant correlation was observed between haplotype GC and AD size (P = 0.020). Our results suggest that MMP-2 gene polymorphisms contribute to type A AD susceptibility. In addition, MMP-2 gene SNPs are associated with AD size, which could be used as a target for the development of new drug therapy.

Diagnostic test accuracy of D-dimer for acute aortic syndrome: systematic review and meta-analysis of 22 studies with 5000 subjects

Diagnostic test accuracy of D-dimer for acute aortic dissection (AAD) has not been evaluated by meta-analysis with the bivariate model methodology. Four databases were electrically searched. We included both case-control and cohort studies that could provide sufficient data concerning both sensitivity and specificity of D-dimer for AAD. Non-English language articles and conference abstract were allowed. Intramural hematoma and penetrating aortic ulcer were regarded as AAD. Based on 22 eligible articles consisting of 1140 AAD subjects and 3860 non-AAD subjects, the diagnostic odds ratio was 28.5 (95% CI 17.6-46.3, I(2) = 17.4%) and the area under curve was 0.946 (95% CI 0.903-0.994). Based on 833 AAD subjects and 1994 non-AAD subjects constituting 12 studies that used the cutoff value of 500 ng/ml, the sensitivity was 0.952 (95% CI 0.901-0.978), the specificity was 0.604 (95% CI 0.485-0.712), positive likelihood ratio was 2.4 (95% CI 1.8-3.3), and negative likelihood ratio was 0.079 (95% CI 0.036-0.172). Sensitivity analysis using data of three high-quality studies almost replicated these results. In conclusion, D-dimer has very good overall accuracy. D-dimer <500 ng/ml largely decreases the possibility of AAD. D-dimer >500 ng/ml moderately increases the possibility of AAD.

Widely Used Types and Clinical Applications of D-Dimer Assay

D-dimers are formed by the breakdown of fibrinogen and fibrin during fibrinolysis. D-dimer analysis is critical for the diagnosis of deep vein thrombosis, pulmonary embolism, and disseminated intravascular coagulation. Modern assays for D-dimer are monoclonal antibody based. The enzyme-linked immunosorbent assay (ELISA) is the reference method for D-dimer analysis in the central clinical laboratory, but is time consuming to perform. Recently, a number of rapid, point-of-care D-dimer assays have been developed for acute care settings that utilize a variety of methodologies. In view of the diversity of D-dimer assays used in central laboratory and point-of-care settings, several caveats must be taken to assure the proper interpretation and clinical application of the results. These include consideration of preanalytical variables and interfering substances, as well as patient drug therapy and underlying disease. D-dimer assays should also be validated in clinical studies, have established cut-off values, and reported according to the reagent manufacturers recommendations.

The current role and future prospects of D-dimer biomarker

D-dimers have been discovered as by-products of fibrinolysis. In situations where the fundamental pathology is associated with increased thrombolytic activity, D-dimer assays could serve an integral role in the clinical workup, and have an already established role in the diagnosis of clinical disorders of venous thromboembolism, and disseminated intravascular coagulation. However, there is growing literature suggesting that this is not the only clinical scenario where D-dimers may be of significance. They may also become an important biomarker in coronary and carotid artery atherosclerosis and aortic diseases. Being a non-invasive and quick means of diagnosis, D-dimers are a cost-effective tool used for diagnosing diseases. With the future being steered in the direction of preventive cardiology, it is imperative for clinicians to understand how to effectively utilize biomarkers in order to diagnose disorders. In this context, we review D-dimer's origin, current clinical utility, and potential future applications.

White blood cell and platelet count as adjuncts to standard clinical evaluation for risk assessment in patients at low probability of acute aortic syndrome

AIMS

Pre-test probability assessment is key in the approach to suspected acute aortic syndromes (AASs). However, most patients with AAS-compatible symptoms are classified at low probability, warranting further evaluation for decision on aortic imaging. White blood cell count, platelet count and fibrinogen explore pathophysiological pathways mobilized in AASs and are routinely assayed in the workup of AASs. However, the diagnostic performance of these variables for AASs, alone and as a bundle, is unknown. We tested the hypothesis that white blood cell count, platelet count and/or fibrinogen at presentation may be applied as additional tools to standard clinical evaluation for pre-test risk assessment in patients at low probability of AAS.

METHODS AND RESULTS

This was a retrospective observational study conducted on consecutive patients managed in our Emergency Department from 2009 to 2014 for suspected AAS. White blood cell count, platelet count and fibrinogen were assayed during evaluation in the Emergency Department. The final diagnosis was obtained by computed tomography angiography. The pre-test probability of AAS was defined according to guidelines. Of 1210 patients with suspected AAS, 1006 (83.1%) were classified at low probability, and 271 (22.4%) were diagnosed with AAS. Within patients at low probability, presence of at least one alteration among white blood cell count >9*10³/µl, platelet count <200*10³/µl and fibrinogen <350 mg/dl was associated with a sensitivity of 95.5% (89.7-98.5%) and a specificity of 18.3% (15.6-21.2%). In patients at low probability, white blood cell count >9*10³/µl and platelet count <200*10³/µl were found as independent predictors of AAS beyond established clinical risk markers. Within patients at low probability, the estimated risk of AAS based on the number of alterations amongst white blood cell count >9*10³/µl and platelet count <200*10³/µl was 2.7% (1.2-5.7%) with zero alterations, 11.3% (8.8-14.3%) with one alteration and 31.9% (24.8-40%) with two alterations ( p<0.001).

CONCLUSION

In addition to standard clinical evaluation, white blood cell count and platelet count may be used in patients at low pre-test probability to fine-tune risk assessment of AAS.