Increased von Willebrand factor in acute stroke patients with atrial fibrillation

Joint effects of atrial fibrillation and prothrombotic genotypes on the risk of ischemic stroke

BACKGROUND

Atrial fibrillation (AF) is a major risk factor for ischemic stroke. Whether prothrombotic single nucleotide polymorphisms (SNPs) impact stroke risk in AF is not well known.

OBJECTIVES

To investigate the joint effects of 5 prothrombotic SNPs and AF on ischemic stroke risk.

METHODS

A subcohort (n = 14 583) was randomly sampled from the Tromsø (1994-2012) and the Trøndelag Health (1995-2008) studies. DNA was genotyped for rs8176719 (ABO blood type), rs6025 (factor [F]V Leiden), rs1799963 (prothrombin G20210A), rs2066865 (fibrinogen-γ), and rs2036914 (F11). Hazard ratios (HRs) with 95% CIs for incident ischemic stroke were estimated by AF status for individual SNPs and by categories of a genetic risk score.

RESULTS

A total of 1091 participants developed AF during follow-up, of whom 169 (15.5%) subsequently had a stroke. Having ≥1 risk allele in prothrombin, FV Leiden, F11, or fibrinogen-γ was not associated with excess stroke risk in AF. In the absence of AF, ≥1 risk allele(s) in ABO was not associated with stroke (HR, 1.03; 95% CI, 0.85-1.25), whereas those with AF and ≥1 risk allele(s) in ABO had a 1.4-fold increased stroke risk compared with those with AF and no risk allele (HR, 1.42; 95% CI, 0.99-2.04). There was no linear increase in stroke risk across categories of the genetic risk score in participants either with or without AF.

CONCLUSION

Most prothrombotic SNPs were not associated with ischemic stroke risk, regardless of AF status. The ABO SNP was associated with ischemic stroke risk in those with AF only.

Altered fibrin clot properties and elevated von Willebrand factor are associated with progression to permanent atrial fibrillation: A cohort study

BACKGROUND

The role of a prothrombotic state in atrial fibrillation (AF) progression to permanent arrythmia (PerAF) is unclear. Formation of denser and poorly lysable fibrin clots has been observed in AF patients also with sinus rhythm in association with higher stroke risk. We investigated whether altered fibrin clot properties and other prothrombotic state markers may contribute to AF transition to PerAF.

METHODS

In the cohort study, in 226 anticoagulated patients (median age 69 years, median CHA2DS2-VASc of 3) with paroxysmal (n = 83, 36.7%) or persistent (n = 143, 63.3%) AF, we assessed at baseline plasma clot permeability (Ks), clot lysis time (CLT), proteins involved in fibrinolysis and von Willebrand factor (vWF) antigen. We recorded patients with PerAF during a median follow-up of 58 months.

RESULTS

During follow-up, PerAF was documented in 62 (27.4%, 5.7%/year) subjects, who had higher prevalence of heart failure, higher body mass index and longer history of arrhythmia. AF transition to PerAF was associated with 25.7% longer CLT in relation to 21.3% higher plasminogen activator inhibitor type 1, and 29% higher vWF compared to the remainder, with no differences in Ks, plasminogen or α2-antiplasmin. By multivariable analysis, CLT (per 10 min, odds ratio [OR] 2.734, 95% confidence interval [CI] 1.788-4.180, p < .001), vWF (per 10%, OR 1.352, 95% CI 1.145-1.596, p < .001) and heart failure (OR 2.637, 95% CI 1.008-6.900, p = .048) were associated with progression to PerAF.

CONCLUSION

Suppressed fibrin clot susceptibility to lysis and elevated vWF could contribute to progression to PerAF despite anticoagulation, which suggests links between blood coagulation and AF progression.

Clinical study on the feasibility of new thrombus markers in predicting massive cerebral infarction

Objective

This study investigated the diagnostic performance of the thrombin-antithrombin complex (TAT), plasmin-α2 plasmin inhibitor complex (PIC), tissue plasminogen activator-plasminogen activator inhibitor complex (t-PAIC), and thrombomodulin (TM) in the early identification of massive cerebral infarction.

Method

A total of 423 patients with cerebral infarction confirmed by imaging examination were divided into the massive cerebral infarction (MCI) group and the non-massive cerebral infarction (NMCI) group. TAT, PIC, t-PAIC, and TM were measured immediately after admission. The diagnostic performance was analyzed by the receiver characteristic operating curve (ROC).

Result

The median plasma concentrations of TAT, PIC, and t-PAIC in patients with MCI at early onset were 5.10 ng/ml, 1.11 μg/ml, and 8.80 ng/ml, respectively, which were higher than those in patients with NMCI (2.20 ng/ml, 0.59 μg/ml, and 7.35 ng/ml), and the difference was statistically significant (P < 0.001). TAT was shown to be an independent risk factor for the development of massive cerebral infarction by a multivariate logistic regression analysis (OR = 1.138). A ROC curve analysis showed that PIC had the best performance in identifying MCI at an early stage (AUC = 82.8%), with a sensitivity of 80.7% and a specificity of 76.2% when the PIC concentration was ≥0.8 μg/ml; TAT had the highest specificity in identifying MCI, with a specificity of 80.6% when the TAT concentration was ≥3.97 ng/ml.

Conclusion

The detection of PIC, TAT, t-PAIC, and TM is a comprehensive assessment of vascular endothelial damage and activation of the coagulation and fibrinolytic systems and has diagnostic value for early identification of patients with MCI, which, together with its ease of detection, can be used as a plasma marker for early identification of large vessel occlusion.

Atrial fibrillation and stroke

INTRODUCTION

Stroke is one of the leading causes of mortality and morbidity globally. Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. It is set to reach epidemic proportions. AF is associated with a five-fold increase in risk of stroke. Strokes caused by AF more often are fatal or result in severe disability. Even though the incidence of stroke has been significantly reduced by oral anticoagulation, AF is thought to account for a significant proportion of cryptogenic strokes where no etiology is identified.

AREAS COVERED

This article reviews the literature related to AF and stroke, pathophysiological insights, diagnosis of AF in stroke patients, and its management (Graphical Abstract).

EXPERT OPINION

The pathophysiology of thrombogenesis that links AF and stroke is not well understood and is an area of active research to identify new therapeutic targets to prevent AF and stroke. As the nature of AF and stroke is multifaceted, an integrated care approach to managing AF and stroke is increasingly essential.

Diagnostic and prognostic blood biomarkers in vascular dementia: From the viewpoint of ischemic stroke

Reliable quantitative blood biomarkers are important in vascular dementia (VaD) because early diagnosis and therapeutic intervention are effective in preventing progression of dementia. Although many blood biomarkers for acute ischemic stroke (AIS) or VaD have been reported, there are few reliable blood biomarkers. VaD and AIS have similar pathological conditions that are associated with small vessel disease (SVD) such as oxidative stress, inflammation, endothelial dysfunction, and neuronal injury. Therefore, it may be possible to find superior blood biomarkers of VaD among AIS blood biomarkers. Owing to recent developments, noncoding RNAs such as microRNA and long noncoding RNA, which can be analyzed using a single drop of blood, are also particularly reliable VaD markers because they stably reflect brain tissue damage. A multimarker combining several blood biomarkers or artificial intelligence technology may also be beneficial to compensate for insufficiencies of a single blood biomarker. This review describes the blood biomarkers of VaD and how they are related to blood biomarkers of AIS.

Blood Biomarkers for Stroke Diagnosis and Management

Biomarkers are objective indicators used to assess normal or pathological processes, evaluate responses to treatment and predict outcomes. Many blood biomarkers already guide decision-making in clinical practice. In stroke, the number of candidate biomarkers is constantly increasing. These biomarkers include proteins, ribonucleic acids, lipids or metabolites. Although biomarkers have the potential to improve the diagnosis and the management of patients with stroke, there is currently no marker that has demonstrated sufficient sensitivity, specificity, rapidity, precision, and cost-effectiveness to be used in the routine management of stroke, thus highlighting the need for additional work. A better standardization of clinical, laboratory and statistical procedures between centers is indispensable to optimize biomarker performance. This review focuses on blood biomarkers that have shown promise for translation into clinical practice and describes some newly reported markers that could add to routine stroke care. Avenues for the discovery of new stroke biomarkers and future research are discussed. The description of the biomarkers is organized according to their expected application in clinical practice: diagnosis, treatment decision, and outcome prediction.

[Biomarkers and atrial fibrillation : Prediction of recurrences and thromboembolic events after rhythm control management]

Atrial fibrillation (AF) is the most common arrhythmia in clinical praxis and is associated with an increased risk for cardio- and cerebrovascular complications leading to an increased mortality. Catheter ablation represents one of the most important and efficient therapy strategies in AF patients. Nevertheless, the high incidence of arrhythmia recurrences after catheter ablation leads to repeated procedures and higher treatment costs. Recently, several scores had been developed to predict rhythm outcomes after catheter ablation. Biomarker research is also of enormous interest. There are many clinical and blood biomarkers pathophysiologically associated with AF occurrence, progression and recurrences. These biomarkers-including different markers in blood (e. g. von Willebrand factor, D‑dimer, natriuretic peptides) or urine (proteins, epidermal grown factor receptor) but also cardiac imaging (echocardiography, computed tomography, magnetic resonance imaging)-could help to improve clinical scores and be useful for individualized AF management and optimized patients' selection for different AF treatment strategies. In this review, the role of diverse biomarkers and their predictive value related to AF-associated complications are discussed.

Plasma fibrin D-dimer and the risk of left atrial thrombus: A systematic review and meta-analysis

BACKGROUND

Plasma fibrin d-dimer has been taken as a marker for thrombus. The aim of this study was to evaluate the relationship between d-dimer (DD) levels and left atrial spontaneous echo contrast (SEC)/left atrial thrombus (LAT).

METHODS

We identified clinical studies by systematic search of MEDLINE and EMBASE databases up to Feb 2016. All observational studies that considered DD as a study factor and trans-esophageal echocardiography (TEE) identified SEC/LAT as an outcome were included. Two reviewers independently selected the studies and extracted the data.

RESULTS

Of the 21 included studies, 16 studies (2652 patients) have compared the mean DD differences between patients with and without an evidence of the presence of SEC/LAT, 9 studies (1667 patients) have estimated the diagnostic value of DD in the presence of LAT, and 11 studies (1856 patients) have available information to calculate a ratio of the presence of LAT among individuals in the top and the bottom third of DD levels. The pooled standardized mean difference (SMD) of DD between patients with and without left atrial SEC and/or LAT was 1.29 [95%CI: 0.51, 2.08], with SMDs of 0.42 [95% CI: 0.08, 0.77] and 2.34 [95% CI: 1.01, 3.68] in SEC/LAT and LAT subgroups, respectively. The combined risk ratio of the presence of LAT among individuals between the top of the distribution of DD levels and that in the bottom third was 3.84 [95% CI: 2.35, 6.28], associating with a mean difference of 0.78 ug/ml (1.10 vs 0.32 ug/ml). The pooled sensitivity, specificity and positive likelihood ratio of DD for LAT were 0.75 [95% CI: 0.65, 0.83], 0.81 [95% CI: 0.59, 0.93] and 4.0 [95% CI: 1.7, 9.9], respectively.

CONCLUSIONS

High plasma fibrin DD was associated with left atrial SEC/LAT, particularly among patients with LAT. DD levels have moderate sensitivity and specificity for diagnosing LAT.

Assessment of Serum UCH-L1 and GFAP in Acute Stroke Patients

A rapid and reliable diagnostic test to distinguish ischemic from hemorrhagic stroke in patients presenting with stroke-like symptoms is essential to optimize management and triage for thrombolytic therapy. The present study measured serum concentrations of ubiquitin C-terminal hydrolase (UCH-L1) and glial fibrillary astrocytic protein (GFAP) in acute stroke patients and healthy controls and investigated their relation to stroke severity and patient characteristics. We also assessed the diagnostic performance of these markers for the differentiation of intracerebral hemorrhage (ICH) from ischemic stroke (IS). Both UCH-L1 and GFAP concentrations were significantly greater in ICH patients than in controls (p < 0.0001). However, exclusively GFAP differed in ICH compared with IS (p < 0.0001). GFAP yielded an AUC of 0.86 for differentiating between ICH and IS within 4.5hrs of symptom onset with a sensitivity of 61% and a specificity of 96% using a cut-off of 0.34ng/ml. Higher GFAP levels were associated with stroke severity and history of prior stroke. Our results demonstrate that blood UCH-L1 and GFAP are increased early after stroke and distinct biomarker-specific release profiles are associated with stroke characteristics and type. We also confirmed the potential of GFAP as a tool for early rule-in of ICH, while UCH-L1 was not clinically useful.

Tissue factor: A potent stimulator of Von Willebrand factor synthesis by human umbilical vein endothelial cells

Inflammation and dysfunction of endothelial cells are thought to be triggers for the secretion of Von Willebrand factor. The aim of this study was to examine the effects of the inflammatory cytokines interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF-α) and the coagulation factors, tissue factor and thrombin on the release and cleavage potential of ultra-large von Willebrand factor (ULVWF) and its cleavage protease by cultured human umbilical vein endothelial cells (HUVEC). HUVEC were treated with IL-6, IL-8, and TNF-α, tissue factor (TF) and thrombin, and combinations thereof for 24 hours under static conditions. The cells were then exposed to shear stress after which the VWF-propeptide levels and the VWF cleavage protease, ADAMTS13 content were measured. All treatments and their combinations, excluding IL-6, significantly stimulated the secretion of VWF from HUVEC. The VWF secretion from the HUVEC was stimulated most by the combination of TF with TNF-α. Slightly lower levels of ADAMTS13 secretion were found with all treatments. This may explain the thrombogenicity of patients with inflammation where extremely high VWF levels and slightly lower ADAMTS13 levels are present.

Current and future bioanalytical approaches for stroke assessment

Efforts are underway to develop novel platforms for stroke diagnosis to meet the criteria for effective treatment within the narrow time window mandated by the FDA-approved therapeutic (<3 h). Blood-based biomarkers could be used for rapid stroke diagnosis and coupled with new analytical tools, could serve as an attractive platform for managing stroke-related diseases. In this review, we will discuss the physiological processes associated with stroke and current diagnostic tools as well as their associated shortcomings. We will then review information on blood-based biomarkers and various detection technologies. In particular, point of care testing that permits small blood volumes required for the analysis and rapid turn-around time measurements of multiple markers will be presented.

Von Willebrand Factor Plasma Levels Variability In Nonvalvular Atrial Fibrillation

Atrial Fibrillation (AF) is the most common cardiac arrhythmia of clinical significance; it increases the risk of mortality due to stroke. The mechanisms behind cerebral thromboembolism in AF are associated with a prothrombotic state, demonstrated by higher levels of von Willebrand Factor (vWF), a multimeric glycoprotein that plays a crucial role in platelet adhesion and aggregation and it has been proposed as a biomarker of endothelial dysfunction. Plasma vWF levels are elevated in patients with nonvalvular Atrial Fibrillation (NVAF) associated to the presence of cardiovascular risk factors. The variability in vWF plasma levels in healthy subjects has a wide distribution, but there is no description available of the variability in AF patients and among types of AF. The aim of this study was to determine the variability of vWF plasma concentrations in patients with NVAF, associated to cardiovascular risk factors. Search strategy included PubMed and Ovid. Keywords used were "Atrial Fibrillation" and "von Willebrand Factor". It includes original articles, with analysis of plasma vWF levels by ELISA, without acute stroke. Review articles and meta-analysis were excluded. Reviewed studies include 22 trials and 6542 patients with nonvalvular AF associated to cardiovascular disease risk factors: age, sex, hypertension, heart failure, diabetes mellitus, prior stroke, coronary artery disease. Variability in vWF plasma levels was wide, with minimum values of 77 IU/dl and maximum values of 245 IU/dl and a mean of 146 IU/dl. Age of patients ranged between 54 and 78 years, and the percentage of males ranged between 23% and 80%. According to type of AF vWF levels were as follows, in paroxysmal AF: 92-264 IU/dl; persistent AF: 76-234 IU/dl; permanent AF: 91-247 IU/dl. The variability in vWF plasma levels is affected by risk factors and the AF type, however vWF levels in AF patients are higher when compared with healthy subjects.

Rhythm outcomes after catheter ablation of atrial fibrillation. Clinical implication of biomarkers

Atrial fibrillation (AF) occurs as the result of numerous complex physiological processes in the atria leading to AF promotion and maintenance. Improved diagnostic techniques have identified various biomarkers which may play an important role in the prediction of AF related outcomes (cardio- and cerebrovascular events, as well as mortality and rhythm outcomes). Biomarkers refer to 'biological markers' and biomarkers in blood, urine as well as imaging marker (eg, dimensions (left atrial diameter and volume), anatomical features (left appendage and pulmonary vein anatomy), and physiological pattern (LAA flow velocity)) may play important role(s) as clinically important indices in relation to outcomes after different therapeutic strategies. However, the main domain in the biomarker field has focused on blood-based biomarkers, which are widely used to predict therapeutic success regarding underlying pathophysiological mechanism, such as inflammation, fibrosis, endothelial damage. This review provides an update of the role of clinically relevant biomarkers in AF, with particular focus on AF rhythm outcomes.

Ischemic stroke biomarkers in blood

Ischemic stroke is a leading cause of adult disability and mortality. With over 15 million strokes occurring every year in the world, methods to better identify patients at risk for stroke are needed, as are methods to improve patient diagnosis and prognosis when stroke occurs. Use of blood-based biomarkers is one method that has been evaluated to predict risk of stroke, diagnose stroke and its causes, predict stroke severity and outcome, and guide prevention therapy. Markers that have been identified include a variety of proteins, nucleic acids and lipids that relate to stroke pathophysiology. The role of blood biomarkers in ischemic stroke is still being defined, and further study is needed to develop blood biomarkers for clinical stroke use. In this review, the authors provide a summary of biomarkers that have been divided by their potential clinical application.

Evolving role of biomarkers in acute cerebrovascular disease

The development of a clinically validated biomarker of acute cerebral ischemia would have the potential to facilitate the use of time-sensitive reperfusion strategies, allow for individualization of patient care by predicting relative risk of hemorrhage and volume of penumbral tissue, and add valuable prognostic information for patients presenting with acute stroke. Additionally, a stroke biomarker might benefit early stage clinical research by serving as a surrogate measure of ischemic injury. Although at present there are no clinically validated biomarkers of acute stroke, previous studies have focused on markers associated with different components of the ischemic cascade, including microglial activation, inflammation, oxidative stress, neuronal injury, hemostasis, and endothelial dysfunction. Evolving technologies have provided high throughput approaches to investigate potential gene and protein signatures, and methods to measure newly discovered markers of cell death and immune responses. Prior to defining the clinical utility of stroke biomarkers, it is critical to understand the inherent limitations of a biomarker-based approach and define its potential value for providing adjunctive diagnostic and prognostic information. The identification and validation of a clinically relevant biomarker, or panel of markers, of stroke will ultimately require incorporation of both stringent research design and assessment in the clinical context in which the marker will be used.

Inflammatory and neuroendocrine biomarkers of prognosis after ischemic stroke

Stroke is the third leading cause of mortality in the USA and one of the leading causes of severe morbidity. It is important to provide stroke patients and physicians with the most accurate prognostic information to optimize care and allocation of healthcare resources. Reliable prognostic markers available during the initial phase after acute stroke may aid clinical decision-making. Several interesting candidate biomarkers have been studied to address prognostic questions; this article will focus on selected inflammatory and neuroendocrine markers. The utility of a biomarker is defined by its ability to improve clinical decision-making and add timely information beyond that readily available from clinical examination and routine imaging. This aim has not been completely achieved yet for any biomarkers, but promising data are available and further studies are ongoing.

[Persistent left atrial thrombus in atrial fibrillation under oral anticoagulation]

The case of a 78-year-old female patient who suffered atrial fibrillation and persistent thrombus in the left atrial appendage despite sufficient anticoagulation is reported. The case is chosen to demonstrate the complexity inherent in prophylaxis as well as risk evaluation of thromboembolism on the basis of clinical and echocardiographic criteria. We also discuss transesophageal echocardiography as the standard diagnostic procedure for detection of intracardiac thrombi prior to cardioversion as well as cardiac computer tomography as an alternative.

Clinical application of blood biomarkers in cerebrovascular disease

Identifying a biomarker or panel of biomarkers of cerebral ischemia would have a major impact on the care of stroke patients by facilitating early management decisions and individualization of care. Biochemical surrogates of cerebral ischemia might also play an important role by identifying relevant pathways for novel therapeutic strategies and by facilitating early clinical trials in cerebrovascular disease. Serum biomarkers related to pathways of hemostasis, oxidation and inflammation, or alterations in glial and neuronal proteins, have been identified but none have been recommended for routine clinical use. This review describes the most promising biomarkers of cerebrovascular disease and the context and limitations in which they have been studied.

Plasma levels of von Willebrand factor are increased in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterised by inappropriate hypertrophy, small-vessel coronary artery disease, myocyte disarray and increased interstitial fibrosis. Microvascular dysfunction is a common finding in HCM and its extent has been proposed as an important prognostic marker. Plasma von Willebrand factor (vWf) is an established marker of endothelial damage or dysfunction; however it has scarcely been studied in HCM. We hypothesised that vWf could be raised in patients with HCM and be related to different variables associated with severity of HCM.

METHODS

We included 124 HCM patients, 93 males, aged 48+/-15 years, 59 healthy control subjects with similar age and sex and 20 patients with ischemic heart disease but clinical stability for the last 6 months. A complete history and clinical examination was performed, including 12-lead electrocardiogram, echocardiography, 24 hours ECG-Holter monitoring, and symptom limited treadmill exercise test. Risk factors for sudden death were evaluated. A blinded cardiac MRI was performed with late enhanced study with Gadolinium. Plasma vWf levels were assayed by commercial ELISA.

RESULTS

Patients showed higher levels of vWf (140.0+/-65.0 UI/ml vs 105.0+/-51.0 UI/ml, p<0.001) even after adjusting for ABO blood group. vWf levels were found raised in patients with severe functional class (168.4+/-65.9 UI/mL vs 132.4+/-60.7 UI/mL, p=0.020), atrial fibrillation (175.8+/-69.4 UI/mL vs 133.0+/-59.0 UI/mL, p=0.005), hypertension (161.4+/-60.8 vs 128.9+/-60.5, p=0.010) obstruction (153.9+/-67.9 vs 128.2+/-57.4 UI/mL, p=0.046) and non sustained ventricular tachycardia (159.3+/-59.1 vs 133.0+/-63.0, p=0.049). vWf correlated with age (r:0.26; p=0.006) and obstruction (r:0.22; p=0.021).

CONCLUSIONS

We show, for the first time, patients with HCM present significantly raised levels of vWf. These are associated with different conditions related to the severity of the disease.