Plasma von Willebrand factor, soluble thrombomodulin, and fibrin D-dimer concentrations in acute onset non-rheumatic atrial fibrillation

Asymmetric Dimethylarginine Is Associated with the Phenomenon of Coronary Slow Flow in Patients with Nonvalvular Atrial Fibrillation

INTRODUCTION

Coronary slow flow phenomena (CSFP) are associated with endothelial and blood component abnormalities in coronary arteries. Asymmetric dimethylarginine (ADMA) can damage the endothelium of the heart or blood vessels in patients with non-valvular atrial fibrillation (NVAF), causing changes in levels of biological indicators. Our aim was to analyze the relationship between ADMA and CSFP in NVAF patients.

METHODS

We consecutively enrolled 134 patients diagnosed with NVAF and underwent coronary angiography, 50 control patients without a history of atrial fibrillation and with normal coronary angiographic flow were included at the same time. Based on the corrected TIMI frame count (CTFC), the NVAF patients were categorized into two groups, CTFC ≤27 frames and CTFC >27 frames. Plasma ADMA, P-selectin (p-sel), von Willebrand factor (vWF), D-dimer (D-Di), plasminogen activator inhibitor 1 (PAI-1), and nitric oxide (NO) were detected by ELISA in the different groups.

RESULTS

We found that plasma ADMA levels were significantly higher among NVAF patients in the CTFC >27 grade group compared with the control or CTFC ≤27 group. In addition, the levels of blood cells and endothelium-related biomarkers (NO, P-selectin, vWF, D-Di, and PAI-1) were significantly altered and correlated with ADMA levels. Multifactorial analysis showed that plasma ADMA (odd ratio [OR; 95% CI]: 1.65 [1.21-2.43], p < 0.001) and left atrial internal diameter (OR [95% CI]: 1.04 [1.02, 1.1], p < 0.001) could be used as independent risk factors for the development of CSFP in patients with NVAF. The ROC curves of ADMA can predict the development of CSFP in NVAF patients. The minimum diagnostic concentration for the development of CSFP in patients was 2.31 µmol/L.

CONCLUSION

Our study demonstrated that CSFP in NVAF patients was associated with high levels of ADMA and left atrial internal diameter. Therefore, aggressive preoperative detection and evaluation of ADMA and left atrial internal diameter can help deal with the intraoperative presence of CSFP.

Imaging and biophysical modelling of thrombogenic mechanisms in atrial fibrillation and stroke

Atrial fibrillation (AF) underlies almost one third of all ischaemic strokes, with the left atrial appendage (LAA) identified as the primary thromboembolic source. Current stroke risk stratification approaches, such as the CHA₂DS₂-VASc score, rely mostly on clinical comorbidities, rather than thrombogenic mechanisms such as blood stasis, hypercoagulability and endothelial dysfunction-known as Virchow's triad. While detection of AF-related thrombi is possible using established cardiac imaging techniques, such as transoesophageal echocardiography, there is a growing need to reliably assess AF-patient thrombogenicity prior to thrombus formation. Over the past decade, cardiac imaging and image-based biophysical modelling have emerged as powerful tools for reproducing the mechanisms of thrombogenesis. Clinical imaging modalities such as cardiac computed tomography, magnetic resonance and echocardiographic techniques can measure blood flow velocities and identify LA fibrosis (an indicator of endothelial dysfunction), but imaging remains limited in its ability to assess blood coagulation dynamics. In-silico cardiac modelling tools-such as computational fluid dynamics for blood flow, reaction-diffusion-convection equations to mimic the coagulation cascade, and surrogate flow metrics associated with endothelial damage-have grown in prevalence and advanced mechanistic understanding of thrombogenesis. However, neither technique alone can fully elucidate thrombogenicity in AF. In future, combining cardiac imaging with in-silico modelling and integrating machine learning approaches for rapid results directly from imaging data will require development under a rigorous framework of verification and clinical validation, but may pave the way towards enhanced personalised stroke risk stratification in the growing population of AF patients. This Review will focus on the significant progress in these fields.

Age-adjusted D-Dimer Thresholds Combined with the Modified Wells Score as a Predictor of Lower Extremity Deep Venous Thrombosis

BACKGROUND

Neurosurgical patients are at an increased risk of deep venous thrombosis (DVT), which, if not properly managed, can lead to pulmonary embolism. This study aimed to investigate the accuracy of age-adjusted D-dimer thresholds combined with the modified Wells score as a predictor for lower extremity DVT diagnosis.

METHODS

We conducted a study among patients aged >50 years with suspected lower extremity DVT in the neurosurgery intensive care unit between December 2019 and December 2020. Receiver operating characteristic curve analysis was performed to examine the diagnostic capacity of age-adjusted D-dimer combined with the modified Wells score.

RESULTS

A total of 233 participants, with an average age of 71.81 ± 12.59 years, were enrolled in the study. The mean D-dimer levels were 0.73 ± 0.39 mg/L. Among the participants, 57 (57.9%, 33 males) were diagnosed with DVT. The age-adjusted D-dimer combined with the modified Wells score had the highest area under the curve for diagnosing lower extremity DVT compared to D-dimer and age-adjusted D-dimer alone, with an AUC of 0.858. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the age-adjusted D-dimer combined with the modified Wells score for DVT diagnosis were 78.95%, 80.68%, 57%, 92.2%, and 80.26%, respectively. When analyzing subgroups, the accuracy was 79.55% for participants with cerebral hemorrhage, 81.69% for those with craniocerebral injury, 74.99% for participants with intracranial infection, and 88.89% for those with craniocerebral tumor.

CONCLUSION

The combination of the age-adjusted D-dimer thresholds with the modified Wells score might effectively predict lower extremity DVT.

N-terminal pro-B-type natriuretic peptide and D-dimer combined with left atrial diameter to predict the risk of ischemic stroke in nonvalvular atrial fibrillation

OBJECTIVES

We aimed to explore the potential role of N-terminal pro-B-type natriuretic peptide (NT-proBNP), d-dimer, and the echocardiographic parameter left atrial diameter (LAD) in identifying and predicting the occurrence of ischemic stroke (IS) in patients with nonvalvular atrial fibrillation (NVAF).

METHODS

We conducted a retrospective study of 445 patients with NVAF in the First Affiliated Hospital of Nanchang University. They were divided into the NVAF (309 cases) and NVAF with stroke (136 cases) groups according to whether acute ischemic stroke (AIS) occurred at admission. Multivariate logistic regression was used to analyze the odds ratio (OR) of NT-proBNP, d-dimer, and LAD for IS. The predictive value of NT-proBNP, d-dimer, and LAD in identifying the occurrence of IS in NVAF was determined by plotting the receiver operating characteristic (ROC) curves.

RESULTS

NT-proBNP, d-dimer, and LAD levels were significantly higher in the NVAF with stroke group than in the NVAF group (p < .05). NT-ProBNP, d-dimer, and LAD were independently associated with IS in NVAF patients (odds ratio [OR] = 1.12, 95% confidence interval [CI]: 1.08-1.16; OR = 1.87, 95% CI: 1.37-2.55; OR = 1.21, 95% CI: 1.13-1.28, p < .01). The optimal cutoff points for NT-ProBNP, d-dimer, and LAD levels to distinguish the NVAF group from the NVAF with stroke group were 715.0 pg/ml, 0.515 ng/ml, and 38.5 mm, respectively, with the area under the curve (AUC) being [0.801 (95% CI: 0.76-0.84); 0.770 (95% CI: 0.72-0.85); 0.752 (95% CI: 0.71-0.80), p < .01]. The combined score of NT-proBNP, d-dimer, and LAD improved the predictive efficacy of the single index, with an AUC of 0.846 (95% CI: 0.81-0.88, p < .01), sensitivity of 77.2%, and specificity of 76.4%.

CONCLUSION

NT-proBNP, d-dimer, and the echocardiographic parameter LAD have outstanding value in predicting the risk of IS in patients with NVAF.

Another possible determinant for ischemic stroke with nonvalvular atrial fibrillation other than conventional oral anticoagulant treatment: The relationship between whole blood viscosity and stroke☆

OBJECTIVES

Patients with nonvalvular atrial fibrillation (NVAF) still experience ischemic stroke despite recommended medications and this could be the consequence of increased whole blood viscosity (WBV). We evaluated the predictive value of WBV for stroke in patients with NVFA despite receiving oral anticoagulant (OAC) therapy.

METHODS

One thousand and forty-three NVAF patients on OAC medication were followed up for median 36.13 ± 18.31 months. WBV was calculated according to the validated de Simone's formula.

RESULTS

WBV was significantly higher in stroke group when compared to non-stroke group at both low shear rate (LSR) and high shear rate (HSR). Multiple regression analysis demonstrated an independent association between WBV and stroke when adjusted for other risk factors.

CONCLUSIONS

WBV appears to be a profitable predictor of ischemic stroke in patients with NVAF receiving OAC.

The association of coagulation and atrial fibrillation: a systematic review and meta-analysis

AIMS

While atrial fibrillation (AF) is suggested to induce a prothrombotic state, increasing thrombotic risk, it is also hypothesized that coagulation underlies AF onset. However, conclusive evidence is lacking. With this systematic review and meta-analysis, we aimed to summarize and combine the evidence on the associations between coagulation factors with AF in both longitudinal and cross-sectional studies.

METHODS AND RESULTS

We systematically searched for longitudinal cohort and cross-sectional studies investigating AF and thrombosis. For longitudinal studies, pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. For cross-sectional studies, we determined pooled standardized mean differences (SMDs) and 95% CIs. A total of 17 longitudinal and 44 cross-sectional studies were included. In longitudinal studies, we found significant associations between fibrinogen (HR 1.05, 95% CI 1.00-1.10), plasminogen activator inhibitor 1 (PAI-1) (HR 1.06, 95% CI 1.00-1.12), and D-dimer (HR 1.10, 95% CI 1.02-1.19) and AF incidence. In cross-sectional studies, we found significantly increased levels of fibrinogen (SMD 0.47, 95% CI 0.20-0,74), von Willebrand factor (SMD 0.96, 95% CI 0.28-1.66), P-selectin (SMD 0.31, 95% CI 0.08-0.54), ß-thromboglobulin (SMD 0.82, 95% CI 0.61-1.04), Platelet Factor 4 (SMD 0.42, 95% CI 0.12-0.7), PAI-1 (1.73, 95% CI 0.26-3.19), and D-dimer (SMD 1.74, 95% CI 0.36-3.11) in AF patients, as opposed to controls.

CONCLUSION

These findings suggest that higher levels of coagulation factors are associated with prevalent and incident AF. These associations are most pronounced with prevalent AF in cross-sectional studies. Limited evidence from longitudinal studies suggests a prothrombotic state underlying AF development.

Endothelial Progenitor Cells as Biomarkers of Cardiovascular Pathologies: A Narrative Review

Endothelial progenitor cells (EPC) may influence the integrity and stability of the vascular endothelium. The association of an altered total EPC number and function with cardiovascular diseases (CVD) and risk factors (CVF) was discussed; however, their role and applicability as biomarkers for clinical purposes have not yet been defined. Endothelial dysfunction is one of the key mechanisms in CVD. The assessment of endothelial dysfunction in vivo remains a major challenge, especially for a clinical evaluation of the need for therapeutic interventions or for primary prevention of CVD. One of the main challenges is the heterogeneity of this particular cell population. Endothelial cells (EC) can become senescent, and the majority of circulating endothelial cells (CEC) show evidence of apoptosis or necrosis. There are a few viable CECs that have properties similar to those of an endothelial progenitor cell. To use EPC levels as a biomarker for vascular function and cumulative cardiovascular risk, a correct definition of their phenotype, as well as an update on the clinical application and practicability of current isolation methods, are an urgent priority.

Biomarkers in the clinical management of patients with atrial fibrillation and heart failure

Atrial fibrillation (AF) and heart failure (HF) are two cardiovascular diseases with an increasing prevalence worldwide. These conditions share common pathophysiologiesand frequently co-exit. In fact, the occurrence of either condition can 'cause' the development of the other, creating a new patient group that demands different management strategies to that if they occur in isolation. Regardless of the temproral association of the two conditions, their presence is linked with adverse cardiovascular outcomes, increased rate of hospitalizations, and increased economic burden on healthcare systems. The use of low-cost, easily accessible and applicable biomarkers may hasten the correct diagnosis and the effective treatment of AF and HF. Both AF and HF effect multiple physiological pathways and thus a great number of biomarkers can be measured that potentially give the clinician important diagnostic and prognostic information. These will then guide patient centred therapeutic management. The current biomarkers that offer potential for guiding therapy, focus on the physiological pathways of miRNA, myocardial stretch and injury, oxidative stress, inflammation, fibrosis, coagulation and renal impairment. Each of these has different utility in current clinincal practice.

Altered fibrin clot properties and fibrinolysis in patients with atrial fibrillation: practical implications

Compelling evidence indicates that a hypercoagulable state occurs in patients with atrial fibrillation (AF) including those in sinus rhythm following paroxysmal and persistent AF. Activation of blood coagulation in AF reflects heightened thrombin generation with the subsequent increased formation of fibrin as evidenced by elevated soluble fibrin monomers and D-dimer. Formation of denser fibrin meshworks, relatively resistant to plasmin-mediated lysis has been demonstrated in patients with AF. The presence of stroke risk factors in AF, such as diabetes, heart failure, hypertension, previous myocardial infarction, or stroke, advanced age have been shown to be linked to the prothrombotic clot characteristics, including reduced clot permeability and lysability. Importantly, biomarkers, including cardiac troponins and N-terminal pro-brain natriuretic peptide, are associated with thrombin generation and fibrin-related markers in AF patients. Recently, increased fibrin clot density (low clot permeability measured in plasma-based assays) and impaired fibrinolysis measured off anticoagulation have been demonstrated to predict ischaemic cerebrovascular events in patients with AF receiving vitamin K antagonists and those on rivaroxaban. The current review summarizes evidence for a role of altered fibrin clot properties and hypofibrinolysis in AF and their prognostic value in terms of adverse events.

Chronic Kidney Disease and Its Impact on a Prothrombotic State in Patients with Atrial Fibrillation

It is unclear whether chronic kidney disease (CKD) increases thromboembolism in atrial fibrillation (AF). We conducted a retrospective cross-sectional analysis of 502 non-anticoagulated AF patients (median age, 66 (60–73) years, median CHA₂DS₂-VASc score, 3.0 (2.0–4.0)) with an estimated glomerular filtration rate (eGFR) ≥ 15 mL/min/1.73 m². Endogenous thrombin potential (ETP), clot permeability (K_s), and clot lysis time (CLT), among others, were determined. Patients with stage 4 CKD (n = 87; 17.3%) had higher ETP and prolonged CLT compared with those with stage 3 CKD. In patients with stages 3 to 4 CKD (n = 180; 35.9%) N-terminal pro-B-type natriuretic peptide predicted low K_s (the lowest quartile, odds ratio [OR] per 100 pg/mL: 1.03, 95% confidence interval [CI]: 1.01–1.06) and prolonged CLT (the top quartile, OR per 100 pg/mL: 1.05, 95% CI: 1.02–1.08), but not high ETP. In the whole cohort, after adjustment for CHA₂DS₂-VASc score, stage 4 CKD, but not stage 3 CKD, predicted high ETP (OR: 9.06; 95% CI: 4.44−18.46) and prolonged CLT (OR: 3.58; 95% CI: 1.76–7.28), but not low K_s. compared to the reference eGFR category. This study is the first to demonstrate the prothrombotic and antifibrinolytic alterations in AF patients with stage 4 CKD, but not stage 3 CKD irrespective of clinical stroke risk factors.

Atrial fibrillation and the prothrombotic state: revisiting Virchow’s triad in 2020

Atrial fibrillation (AF) is characterised by an increased risk of pathological thrombus formation due to a disruption of physiological haemostatic mechanisms that are better understood by reference to Virchow’s triad of ‘abnormal blood constituents’, ‘vessel wall abnormalities’ and ‘abnormal blood flow’. First, there is increased activation of the coagulation cascade, platelet reactivity and impaired fibrinolysis as a result of AF per se, and these processes are amplified with pre-existing comorbidities. Several prothrombotic biomarkers including platelet factor 4, von Willebrand factor, fibrinogen, β-thromboglobulin and D-dimer have been implicated in this process. Second, structural changes such as atrial fibrosis and endothelial dysfunction are linked to the development of AF which promote further atrial remodelling, thereby providing a suitable platform for clot formation and subsequent embolisation. Third, these factors are compounded by the presence of reduced blood flow secondary to dilatation of cardiac chambers and loss of atrial systole which have been confirmed using various imaging techniques. Overall, an improved understanding of the various factors involved in thrombus formation will allow better clinical risk stratification and targeted therapies in AF.

Paroxysmal Atrial Fibrillation: Insight Into the Intimate Mechanisms of Coagulation

Background

Atrial fibrillation (AF) is a hypercoagulable state. However, the intimate mechanisms leading to impaired coagulation and the timing of their activation are unclear. The aim of the study was to investigate the factors that initiate the coagulation cascade in the early hours (up to 48 h) of clinical manifestation of paroxysmal atrial fibrillation (PAF).

Methods

Tissue factor (TF) level, coagulation activity of factor VII (FVIIa), factor XII (FXIIa) and factor XI (FXIa) were measured in plasma of 51 non-anticoagulated patients (26 men and 25 women, aged 59.84 ± 11.42 years) and 52 controls (26 men and 26 women, aged 59.50 ± 10.53 years) by enzyme-linked immunoassays and kinetic assays.

Results

TF was higher in the PAF group (268.63 ± 90.62 pg/mL vs. 170.21 ± 66.19 pg/mL, P < 0.001) as well as FVIIa (170.82±59.39% vs. 95.17±37.90%, P < 0.001), FXIIa (218.31±84.04% vs. 148.41±53.94%, P < 0.001) and FXIa (178.41±55.94% vs. 111.75±37.33%, P < 0.001). Regression analysis showed that in the first 6 h of the disease, increase in time led to increase in FXIIa (r = 0.25, P < 0.05), FXIa (r = 0.75, P < 0.05), TF level (r = 0.25, P < 0.05) and FVIIa (r = 0.25, P < 0.05).

Conclusion

Hemocoagulation changes were observed even < 6 h after the onset of the disease. They suggest that PAF has an early tendency for hypercoagulability, with the involvement of the intrinsic and extrinsic pathways of coagulation.

Effects of Rivaroxaban on Biomarkers of Coagulation and Inflammation: A Post Hoc Analysis of the X-VeRT Trial

Introduction  This X-VeRT (eXplore the efficacy and safety of once-daily oral riVaroxaban for the prevention of caRdiovascular events in patients with nonvalvular aTrial fibrillation scheduled for cardioversion) substudy evaluated the effects of treatment with rivaroxaban or a vitamin-K antagonist (VKA) on levels of biomarkers of coagulation (D-dimer, thrombin–antithrombin III complex [TAT] and prothrombin fragment [F1.2]) and inflammation (high sensitivity C-reactive protein [hs-CRP] and high-sensitivity interleukin-6 [hs-IL-6]) in patients with atrial fibrillation (AF) who were scheduled for cardioversion and had not received adequate anticoagulation at baseline (defined as, in the 21 days before randomization: no oral anticoagulant; international normalized ratio <2.0 with VKA treatment; or <80% compliance with non-VKA oral anticoagulant treatment).

Methods  Samples for biomarker analysis were taken at baseline ( n  = 958) and treatment completion (42 days after cardioversion; n  = 918). The influence of clinical characteristics on baseline biomarker levels and the effect of treatment on changes in biomarker levels were evaluated using linear and logistic models.

Results  Baseline levels of some biomarkers were significantly associated with type of AF (D-dimer and hs-IL-6) and with history of congestive heart failure (hs-CRP, D-dimer, and hs-IL-6). Rivaroxaban and VKA treatments were associated with reductions from baseline in levels of D-dimer (−32.3 and −37.6%, respectively), TAT (−28.0 and −23.1%, respectively), hs-CRP (−12.5 and −17.9%, respectively), and hs-IL-6 (−9.2 and −9.8%, respectively). F1.2 levels were reduced from baseline in patients receiving a VKA (−53.0%) but not in those receiving rivaroxaban (2.7%).

Conclusion  Anticoagulation with rivaroxaban reduced levels of key inflammation and coagulation biomarkers to a similar extent as VKAs, with the exception of F1.2. Further investigation to confirm the value of these biomarkers in patients with AF is merited.

Effect of warfarin versus aspirin on blood viscosity in cardioembolic stroke with atrial fibrillation: a prospective clinical trial

Background

Warfarin is evidence-based therapy for the prevention of cardioembolic stroke, but has not been studied for its effects on whole blood viscosity (WBV). This study investigated the effect of warfarin versus aspirin on WBV in patients presenting with non-valvular atrial fibrillation (NVAF) and acute cardioembolic stroke.

Methods

We enrolled patients with acute cerebral infarction, aged 56–90 years who had NVAF, CHADS₂ score ≥ 2, presenting with mild-to-moderate stroke (National Institute of Health Stroke Scale (NIHSS) score < 20 and modified Rankin Scale (2mRS) score < 4) in a single center. The patients were alternately assigned to warfarin or aspirin groups. Post-treatment WBV was assessed after international normalized ratio (INR) reached target range [2, 3] for patients in the warfarin group, and 5 days after baseline in the aspirin group.

Results

Total 67 patients were included, and 56 completed this study (33 warfarin and 23 aspirin). Compared to baseline values, warfarin reduced post-treatment BV at all shear rates. The BV reductions greater than 1 cP measured at shear rates of 300, 150, 5, and 1 s^− 1 were independently and significantly associated with warfarin treatment compared to aspirin after adjusting for age, sex, CHA₂DS₂-VASc scores, and baseline hematocrit.

Conclusions

Warfarin confers greater reductions in BV than aspirin in patients with acute cardioembolic stroke. BV could be a useful method to estimate thrombotic risk in patients receiving warfarin.

Trial registration

KCT0001291, Date of Registration: 2014-12-01

The diagnostic efficacy of cardiac CTA combined with D-dimer assay for the detection of left atrial thrombus in patients with atrial fibrillation

PURPOSE

We aimed to evaluate a combination diagnostic method of single-phased, single-contrast injection cardiac computed tomography angiography CTA combined with age-adjusted D-dimer assay for diagnosis of left atrial/left atrial appendage (LA/LAA) thrombus in comparison to transesophageal echocardiography (TEE) in patients with atrial fibrillation. The addition of D-dimer to the CTA is to increase specificity, since CTA is part of the combined method.

MATERIALS AND METHODS

Between October 2016 and December 2017, 113consective patients with non-valvular or valvular AF (male: 72.6%; mean age: 57.9 ± 11.5 y) underwent diagnostic work-up, included TEE, single-phased, single contrast injection cardiac CTA, and age-adjusted D-dimer assay, for the evaluation of LA/LAA thrombus formation.

RESULTS

Cardiac CTA identified 32 patients with filling defects in LA or LAA. Of these patients, 17 had an elevated D-dimer value according to age-adjusted cut-off. TEE detected definitive thrombus formation in 15 patients. Using TEE as the reference standard, the combination diagnostic method had a sensitivity of 100.0%, specificity of 97.9%, positive predictive value (PPV) of 88.2, and negative predictive value of 100.0%. Further, compared to cardiac CTA alone, the combination diagnostic method had significantly better specificity (82.7% vs. 97.9%, respectively; p < 0.01) and PPV (46.9% vs. 88.2%, respectively; p < 0.01).

CONCLUSION

The combination diagnostic method comprising single-phase, single-contrast injection cardiac CTA and age-adjusted D-dimer assay had good diagnostic efficacy for the detection of LA/LAA thrombus in patients with AF. The combination diagnostic method had significantly better specificity and PPV than cardiac CTA alone. The presented diagnostic approach could potentially facilitate rapid diagnosis or exclusion of left atrial thrombus under emergency situation or when TEE is un-available, with good diagnostic efficacy and no TEE related risks.

Cardiolipotoxicity, Inflammation, and Arrhythmias: Role for Interleukin-6 Molecular Mechanisms

Fatty acid infiltration of the myocardium, acquired in metabolic disorders (obesity, type-2 diabetes, insulin resistance, and hyperglycemia) is critically associated with the development of lipotoxic cardiomyopathy. According to a recent Presidential Advisory from the American Heart Association published in 2017, the current average dietary intake of saturated free-fatty acid (SFFA) in the US is 11–12%, which is significantly above the recommended <10%. Increased levels of circulating SFFAs (or lipotoxicity) may represent an unappreciated link that underlies increased vulnerability to cardiac dysfunction. Thus, an important objective is to identify novel targets that will inform pharmacological and genetic interventions for cardiomyopathies acquired through excessive consumption of diets rich in SFFAs. However, the molecular mechanisms involved are poorly understood. The increasing epidemic of metabolic disorders strongly implies an undeniable and critical need to further investigate SFFA mechanisms. A rapidly emerging and promising target for modulation by lipotoxicity is cytokine secretion and activation of pro-inflammatory signaling pathways. This objective can be advanced through fundamental mechanisms of cardiac electrical remodeling. In this review, we discuss cardiac ion channel modulation by SFFAs. We further highlight the contribution of downstream signaling pathways involving toll-like receptors and pathological increases in pro-inflammatory cytokines. Our expectation is that if we understand pathological remodeling of major cardiac ion channels from a perspective of lipotoxicity and inflammation, we may be able to develop safer and more effective therapies that will be beneficial to patients.

The prothrombotic state in atrial fibrillation: pathophysiological and management implications

Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia and is associated with significant morbidity and mortality. There is plenty of evidence available to support the presence of a prothrombotic or hypercoagulable state in AF, but the contributory factors are multifactorial and cannot simply be explained by blood stasis. Abnormal changes in atrial wall (anatomical and structural, as ‘vessel wall abnormalities’), the presence of spontaneous echo contrast to signify abnormal changes in flow and stasis (‘flow abnormalities’), and abnormal changes in coagulation, platelet, and other pathophysiologic pathways (‘abnormalities of blood constituents’) are well documented in AF. The presence of these components therefore fulfils Virchow’s triad for thrombogenesis. In this review, we present an overview of the established and professed pathophysiological mechanisms for thrombogenesis in AF and its management implications.

Left Atrial or Left Atrial Appendage Thrombus Resolution After Adjustment of Oral Anticoagulant Treatment

BACKGROUND

There are few reports about non-vitamin K antagonist oral anticoagulant (NOAC) treatment for resolution of left atrium (LA) or left atrial appendage (LAA) thrombus. LAA thrombus is an important cause of cardiogenic cerebral thromboembolism, and the detection rate increases due to more and more patients receiving catheter ablation. However, the results from NOAC use for LA or LAA thrombus are still unknown in real-world practice. The aim of this study was to discover the resolution of LA or LAA thrombus after anticoagulant treatment in real-world practice.

METHOD

From January 2013 to December 2016, a total 864 patients underwent transesophageal echocardiography (TEE), and 41 cases of LA or LAA thrombus were detected in our hospital. Among them, a total of 22 patients underwent follow-up TEE to detect the resolution of LA or LAA thrombus.

RESULT

The average age of the study patients was 72.0 ± 11 years old, and 61% were male. The average CHA2DS2-VASc scores were 3.76 ± 2.01 points. A total of 22 patients underwent follow-up TEE, and 19 (86.4%) patients presented LA or LAA thrombus resolution. The average resolution duration was 258.47 ± 218.17 days. One-year all-cause mortality was 4.9%, and the incidence of ischemic stroke was 4.9%. Most physicians favored titration of the dosage of NOAC or warfarin in real-world practice.

CONCLUSION

In real-world practice, most physicians favored titration of the dosage of NOAC or warfarin for LA or LAA thrombus. LA or LAA thrombus could exist if the patient received a reduced dose of NOAC. High frequency of LAA or LA thrombi could resolve, and a low incidence of ischemic stroke occurred after adjustment of oral anticoagulant treatment.

Atrial endocardial expression of von Willebrand factor and thrombomodulin is associated with recurrence after minimally invasive surgical atrial fibrillation ablation

OBJECTIVES

We retrospectively analysed data from non-valvular atrial fibrillation (AF) patients who underwent minimally invasive surgical AF ablation at our centre. Our purpose was to explore the atrial endocardial expression of von Willebrand factor (vWF) and thrombomodulin (TM) and their association with rhythm results after the procedure.

METHODS

From January 2014 to May 2015, 60 patients underwent minimally invasive surgical AF ablation at our centre. Left atrial appendage samples were obtained during the procedure and immunohistochemistry for endocardial markers including vWF and TM was performed and semi-quantitatively graded. All patients underwent postoperative rhythm documentation at 3, 6, 12 and 24 months.

RESULTS

At the 2-year interval, 49 (82%) patients maintained sinus rhythm, and all patients were asymptomatic. Univariate analysis shows that patients with AF recurrence have higher vWF score 2/3 and longer AF duration (P < 0.05). In the multivariate analysis, AF duration, vWF score, TM score, left atrial diameter (LAD) and non-paroxysmal AF are included. The result suggests that higher vWF score 2/3, lower TM score 0/1 and non-paroxysmal AF are statistically significant (P < 0.05). In addition, higher vWF score 2/3 is associated with larger LAD (45.2 ± 5.6 mm vs 41.2 ± 7.6 mm, P = 0.032), while higher TM score 2/3, on the other hand, is associated with smaller LAD (44.6 ± 6.1 mm vs 39.9 ± 7.8 mm, P = 0.032). The Kaplan-Meier analysis shows that higher vWF score 2/3 and lower TM score 0/1 appear to be accompanied with higher recurrence rate (vWF: P = 0.021; TM: P = 0.036).

CONCLUSIONS

Atrial endocardial expression of vWF and TM might be associated with recurrence after minimally invasive surgical AF ablation. Patients with AF recurrence seem to have elevated vWF expression and decreased TM expression.

[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.

Effect of sinus rhythm restoration on markers of thrombin generation in atrial fibrillation

Background

Atrial fibrillation (AF) confers a hypercoagulable state; however, it is not clear whether restoration of sinus rhythm is associated with normalisation of markers of thrombogenesis. We studied the impact of sustained sinus rhythm on prothrombotic markers, and their predictive abilities in foreseeing rhythm outcome after cardioversion.

Methods

In a double blind, placebo-controlled study, 171 patients referred for electrical cardioversion of persistent AF were randomised to receive candesartan or placebo for 3-6 weeks before and 6 months after cardioversion. Endogenous thrombin potential (ETP), prothrombin fragment 1 + 2 (F1 + 2) and D-dimer were measured before cardioversion and at end of study. These markers were also measured in a reference group comprising 49 subjects without AF.

Results

The markers remained unchanged in those 28 patients who maintained sinus rhythm. Discontinuation of warfarin treatment in a subset of 13 low-risk patients in sinus rhythm was associated with significantly higher levels of D-dimer and F1 + 2 compared to the reference group; D-dimer (456 ng/mL (276, 763) vs. 279 ng/mL (192, 348), p = 0.002) and F1 + 2 (700 pmol/L (345, 845) vs. 232 pmol/L (190, 281), p < 0.001). None of the markers were associated with rhythm outcome after electrical cardioversion.

Conclusions

Sustained sinus rhythm for 6 months after cardioversion for AF had no impact on ETP, F1 + 2 or D-dimer levels. Discontinuation of warfarin in low-risk patients with sustained sinus rhythm was associated with significantly higher levels of D-dimer and F1 + 2 compared to the reference group. Our results suggest persistent hypercoagulability in AF patients despite long-term maintenance of sinus rhythm.

Trial registration

The CAPRAF study was registered at clinicaltrials.gov (NCT00130975) in August 2005.

Predictive Role of Coagulation, Fibrinolytic, and Endothelial Markers in Patients with Atrial Fibrillation, Stroke, and Thromboembolism: A Meta-Analysis, Meta-Regression, and Systematic Review

Background

The pathophysiological mechanism associated with the higher prothrombotic tendency in atrial fibrillation (AF) is complex and multifactorial. However, the role of prothrombotic markers in AF remains inconclusive.

Material/Methods

We conducted a meta-analysis of observational studies evaluating the association of coagulation activation, fibrinolytic, and endothelial function with occurrence of AF and clinical adverse events. A comprehensive subgroup analysis and meta-regression was performed to explore potential sources of heterogeneity.

Results

A literature search of major databases retrieved 1703 studies. After screening, a total of 71 studies were identified. Pooled analysis showed the association of coagulation markers (D-dimer (weighted mean difference (WMD)=197.67 and p<0.001), fibrinogen (WMD=0.43 and p<0.001), prothrombin fragment 1–2 (WMD=0.53 and p<0.001), antithrombin III (WMD=23.90 and p=0.004), thrombin-antithrombin (WMD=5.47 and p=0.004)); fibrinolytic markers (tissue-type plasminogen activator (t-PA) (WMD=2.13 and p<0.001), plasminogen activator inhibitor (WMD=11.44 and p<0.001), fibrinopeptide-A (WMD=4.13 and p=0.01)); and endothelial markers (von Willebrand factor (WMD=27.01 and p<0.001) and soluble thrombomodulin (WMD=3.92 and p<0.001)) with AF.

Conclusions

The levels of coagulation, fibrinolytic, and endothelial markers have been reported to be significantly higher in AF patients than in SR patients.

Does von Willebrand factor improve the predictive ability of current risk stratification scores in patients with atrial fibrillation?

Von Willebrand factor (vWF) is a biomarker of endothelial dysfunction. We investigated its role on prognosis in anticoagulated atrial fibrillation (AF) patients and determined whether its addition to clinical risk stratification schemes improved event-risk prediction. Consecutive outpatients with non-valvular AF were recruited and rates of thrombotic/cardiovascular events, major bleeding and mortality were recorded. The effect of vWF on prognosis was calculated using a Cox regression model. Improvements in predictive accuracy over current scores were determined by calculating the integrated discrimination improvement (IDI), net reclassification improvement (NRI), comparison of receiver-operator characteristic (ROC) curves and Decision Curve Analysis (DCA). 1215 patients (49% males, age 76 (71–81) years) were included. Follow-up was almost 7 years. Significant associations were found between vWF and cardiovascular events, stroke, mortality and bleeding. Based on IDI and NRI, addition of vWF to CHA₂DS₂-VASc statistically improved its predictive value, but c-indexes were not significantly different. For major bleeding, the addition of vWF to HAS-BLED improved the c-index but not IDI or NRI. DCA showed minimal net benefit. vWF acts as a simple prognostic biomarker in AF and, whilst its addition to current scores statistically improves prediction for some endpoints, absolute changes and impact on clinical decision-making are marginal.

Application of Biomarkers for Risk Stratification in Patients with Atrial Fibrillation

BACKGROUND

Atrial fibrillation is the most common sustained arrhythmia and an important contributor to cardiovascular morbidity and mortality. Several strategies have been proposed for prediction of outcomes and individualization of treatments to better balance the benefits of stroke prevention and risks of bleeding during anticoagulation.

CONTENT

The availability of analytically more specific and sensitive methods to measure circulating biomarkers of cellular and organ stress and dysfunction has led to testing of their utility in several cardiovascular conditions. In patients with atrial fibrillation, biomarkers of myocardial injury (troponin) and cardiovascular stress and dysfunction (natriuretic peptides, growth differentiation factor 15), myocardial fibrosis (galectin-3), renal dysfunction (creatinine, cystatin C), inflammation (C-reactive protein, cytokines) and coagulation activity (d-dimer) have been found associated with underlying pathophysiology, clinical outcomes and effects of treatment. Measurements of these markers might therefore expand the understanding of the pathophysiology, improve risk assessment and optimize treatment in individual patients with atrial fibrillation.

SUMMARY

Biomarkers for risk stratification have potential roles as tools for evaluation of patients with atrial fibrillation and for selection of the best treatment strategies to prevent stroke, major bleeding, and mortality.

Early Changes in the Antithrombin and Thrombin-Antithrombin Complex in Patients With Paroxysmal Atrial Fibrillation

Background

Data on coagulation changes in paroxysmal atrial fibrillation (PAF) are scarce. The aim of this study was to examine plasma antithrombin (AT) levels and activity as well as thrombin-antithrombin (TAT) complex levels in the early hours of the clinical manifestation of PAF.

Methods

Fifty-one patients (26 men and 25 women; mean age 59.84 ± 1.60 years) were consecutively selected with PAF duration < 24 hours, and 52 controls (26 men and 26 women; mean age 59.50 ± 1.46 years) matched the patients in terms of gender, age and comorbidities. Plasma levels and activity of AT and levels of the covalent TAT complex were studied once in each study participant.

Results

AT plasma levels in PAF patients were statistically significantly lower compared to controls (164.69 ± 10.51 vs. 276.21 ± 8.29 μg/mL, P < 0.001). Plasma activity of the anticoagulant was also significantly lower in PAF (71.33±4.87 vs. 110.72±3.09%, P < 0.001). TAT complex concentration in plasma was higher in the patient group (5.32 ± 0.23 vs. 3.20 ± 0.14 μg/L, P < 0.001).

Conclusion

We can say that PAF is associated with significantly reduced AT levels and activity and increased levels of TAT complex during the first 24 hours after its manifestation. These changes indicate a reduced activity of AT anticoagulant system, which is a probable prerequisite for the established enhanced coagulation (high TAT complex levels).

Decreased Activity of the Protein C Anticoagulant Pathway in the Early Hours of Paroxysmal Atrial Fibrillation

BACKGROUND

Increased coagulation activity has been established in paroxysmal atrial fibrillation (PAF), but data on the anticoagulant system are scarce.

PURPOSE

To examine the protein C anticoagulant pathway in the early hours of the disease.

MATERIALS AND METHODS

Fifty-one patients (26 men and 25 women; mean age 59.84 ± 1.60 years) and 52 controls (26 men and 26 women; mean age 59.50 ± 1.46 years) were selected for the study. Protein C antigen and its activity, total protein S, free protein S and its activity, soluble forms of endothelial protein C receptor (sEPCR), and thrombomodulin (sTM) were examined in the plasma.

RESULTS

The indicators were studied in patients between the 2nd and the 24th hour after the onset of arrhythmia. Levels of protein C were significantly elevated in patients compared to controls (111.40% ± 6.66% vs 94.83% ± 4.47%; P = .039). Protein C activity showed significant reduction in PAF (73.13% ± 5.80% vs 103.3% ± 3.80%; P < .001). Total protein S levels did not differ significantly (108.20% ± 4.07% vs 102.40% ± 3.65%; P = .30). Free protein S (76.81% ± 6.01% vs 122.10% ± 3.97%; P < .001) and its activity (71.39% ± 6.27% vs 119.50% ± 6.54%; P < .001) were reduced in patients. Higher levels of sEPCR (203.10 ± 10.33 vs 133.10 ± 7.37 ng/mL; P < .001) and sTM (6.50±0.40 vs 4.48±0.28 ng/mL; P < .001) were measured in PAF.

CONCLUSION

Protein C activity is reduced still in the first hours (until the 24th hour) of PAF clinical manifestation, determining reduced activity of the anticoagulant pathway as a whole. The established low levels of free protein S and its activity as well as low sEPCR and sTM levels are a possible explanation of the changes in protein C activity.

Association of hemostatic markers with atrial fibrillation: a meta-analysis and meta-regression

BACKGROUND

There is growing evidence that indicates the presence of a prothrombotic state in atrial fibrillation (AF). However, the role of hemostatic markers in AF remains inconclusive.

METHODS

We conducted a meta-analysis of observational studies to evaluate the association between hemostatic markers and AF. A meta-regression was performed to explore potential sources of heterogeneity.

RESULTS

A total of 59 studies met our inclusion criteria for the meta-analysis. For platelet activation, increased circulating platelet factor-4, β-thromboglobulin (BTG) and P-selectin were significantly higher in AF cases compared with controls (standardized mean difference [SMD][95% confidence interval (CI)]: 1.72[0.96-2.49], 1.61[1.03-2.19] and 0.50[0.23-0.77], respectively). For coagulation activation, increased levels of plasma D-dimer, fibrinogen, thrombin-antithrombin, prothrombin fragment 1+2, and antithrombin-III were significantly associated with AF (SMD[95% CI]: 1.82[1.38-2.26], 0.72[0.55-0.89], 0.42[0.13-0.72], 1.00 [0.00-1.99] and 1.38[0.16-2.60], respectively). For fibrinolytic function, tissue-type plasminogen activator and plasminogen activator inhibitor-1 were significantly increased in AF cases compared with controls (SMD[95% CI]: 0.86[0.04-1.67] and 0.87[0.28-1.47], respectively) but the associations became nonsignificant after performing subgroup analysis by anticoagulants treatment status. For endothelial function, increased von Willebrand factor was significantly associated with AF (SMD, 0.79; 95% CI, 0.60-0.99); however, no association was observed for soluble thrombomodulin (SMD, 0.60; 95% CI, -0.13-1.33).

CONCLUSIONS

Increased circulating hemostatic factors (PF-4, BTG, P-selectin, D-dimer, fibrinogen, TAT, F1+2, AT- III, and vWf) are significantly associated with AF. Future research is necessary to elucidate the precise mechanism of the prothrombotic state and how hemostatic markers promote thromboembolism in AF.

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.

Impaired platelet nitric oxide response in patients with new onset atrial fibrillation

BACKGROUND

Clinical factors associated with thromboembolic risk in AF patients are well characterized and include new onset AF. Biochemically, AF is associated with inflammatory activation and impairment of nitric oxide (NO) signalling, which may also predispose to thromboembolism: the bases for variability in these anomalies have not been identified. We therefore sought to identify correlates of impaired platelet NO signalling in patients hospitalized with atrial fibrillation (AF), and to evaluate the impact of acuity of AF.

METHODS

87 patients hospitalized with AF were evaluated. Platelet aggregation, and its inhibition by the NO donor sodium nitroprusside, was evaluated using whole blood impedance aggregometry. Correlates of impaired NO response were examined and repeated in a "validation" cohort of acute cardiac illnesses.

RESULTS

Whilst clinical risk scores were not significantly correlated with integrity of NO signalling, new onset AF was associated with impaired NO response (6 ± 5% inhibition versus 25 ± 4% inhibition for chronic AF, p<0.01). New onset AF was a multivariate correlate (p<0.01) of impaired NO signalling, along with platelet ADP response (p<0.001), whereas the associated tachycardia was not. Platelet ADP response was predicted by elevation of plasma thrombospondin-1 concentrations (p<0.01). Validation cohort evaluations confirmed that acute AF was associated with significant (p<0.05) impairment of platelet NO response, and that neither acute heart failure nor acute coronary syndromes were associated with similar impairment.

CONCLUSION

Recent onset of AF is associated with marked impairment of platelet NO response. These findings may contribute to thromboembolic risk in such patients.

Hypercoagulability, D-dimer and atrial fibrillation: an overview of biological and clinical evidence

Atrial fibrillation (AF) is the most common among the severe cardiac arrhythmias and carries a significant risk of mortality and morbidity in the general population. The most important complication is represented by development of one or more thrombi in the left atrium of the dyskinetic heart, and their successive cerebral and peripheral embolization. The pathophysiological basis of the thromboembolic complications in AF entails the presence of a hypercoagulable state, which is mirrored by increased concentrations of a variety of prothrombotic markers. D-dimer is universally considered the gold standard among the various biomarkers that reflect activation of coagulation, fibrinolysis, or both, and several studies have assessed its diagnostic and prognostic role in AF. With a few exceptions and despite a broad heterogeneity in the study designs, published data seem to demonstrate that D-dimer values may be associated with the presence of atrial thrombosis, may be predictive of primary adverse outcomes and death, may be correlated with cerebral infarction volume, and may also be a useful parameter for assessing the degree of hypercoagulability of AF patients after cardioversion. If larger prospective studies confirm these findings, D-dimer assessment may hence become an integral part of the clinical decision-making in patients with AF.

Stroke prevention in atrial fibrillation in heart failure

Heart failure and atrial fibrillation are major problems of modern cardiology with important clinical, prognostic, and socioeconomic implications. The risks are high morbidity, impaired quality of life, poor outcome, and increased risk of stroke. Oral anticoagulation with vitamin K antagonists or novel licensed medicines should be considered unless contraindicated. Possible benefits of sinus rhythm maintenance are not entirely clear and need to be explored further. Relatively scarce data are available on stroke prevention in atrial fibrillation in heart failure with preserved ejection fraction; this requires further research.

Unanswered questions in patients with concurrent atrial fibrillation and acute coronary syndrome

The best regimen for the long-term management of patients with atrial fibrillation who present with an acute coronary syndrome or require placement of a coronary stent remains unclear. Clinicians need to understand the risk of stroke, stent thrombosis, and major bleeding associated with treating these patients. Numerous studies and risk assessment schemes provide clinicians with an estimation of the risk of stroke, stent thrombosis, and major bleeding that may be associated with the use or avoidance of dual antiplatelet therapy with concurrent anticoagulation therapy (triple therapy). This review discusses the special antithrombotic needs in patients who have atrial fibrillation and either acute coronary syndrome or a requirement for percutaneous coronary intervention, including the published evidence for non-vitamin K oral anticoagulants, and the unanswered questions in this patient population. In conclusion, until the results of additional ongoing or planned randomized trials are known, clinicians must continue to rely on expert opinion and their own clinical judgment when treating these patients.

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.

Evidence-based percutaneous closure of the left atrial appendage in patients with atrial fibrillation

Atrial fibrillation is the most common cardiac arrhythmia, and its prevalence is increasing. Cardioembolic stroke, most of the times secondary to thrombus formation in the left atrial appendage, is its most feared and life threatening consequence. Oral anticoagulation with vitamin-K-antagonists is currently the most used prophylaxis for stroke in patients with atrial fibrillation; unfortunately, its benefits are limited by a narrow therapeutic window and an increased risk for bleeding, making it often undesired. Percutaneous occlusion of the left atrial appendage is a novel alternative strategy for cardioembolic stroke prophylaxis in patients with atrial fibrillation at a high risk of stroke but with contraindication for long-term oral anticoagulation therapy. At present, several devices have been developed specifically for percutaneous occlusion of the left atrial appendage. Current results show good feasibility and efficacy for these devices, with a high rate of successful implantation, although also associated with the inherent potential periprocedural complications. This work reviews the current state of the art of percutaneous left atrial appendage closure for stroke prophylaxis in patients with atrial fibrillation.

Biomarkers in atrial fibrillation: a clinical review

Assessment of atrial fibrillation (AF)-associated stroke risk is at present mainly based on clinical risk scores such as CHADS2 and CHA2DS2-VASc, although these scores provide only modest discrimination of risk for individual patients. Biomarkers derived from the blood may help refine risk assessment in AF for stroke outcomes and for mortality. Recent studies of biomarkers in AF have shown that they can substantially improve risk stratification. Cardiac biomarkers, such as troponin and natriuretic peptides, significantly improve risk stratification in addition to current clinical risk stratification models. Similar findings have recently been described for markers of renal function, coagulation, and inflammation in AF populations based on large randomized prospective clinical trials or large community-based cohorts. These new findings may enable development of novel tools to improve clinical risk assessment in AF. Biomarkers in AF may also improve the understanding of the pathophysiology of AF further as well as potentially elucidate novel treatment targets. This review will highlight novel associations of biomarkers and outcomes in AF as well as recent progress in the use of biomarkers for risk stratification.

Biochemical predictors of cardiac rhythm at 1 year follow-up in patients with non-valvular atrial fibrillation

C-reactive protein (CRP) is increased in patients with atrial fibrillation (AF) and it might predict the lack of sinus rhythm maintenance in the long term follow-up. Scarce data have been reported relating endothelial dysfunction and/or haemostatic or platelet markers to sinus rhythm maintenance in AF patients. We aimed to determine whether some biochemical markers including soluble thrombomodulin (sTM), soluble P-selectin, thrombin-antithrombin (TAT) complex and CRP levels could predict sinus rhythm maintenance at 1 year follow-up in non-valvular AF patients. 130 patients (70 males, mean age 67 ± 13 years) with newly diagnosed AF naïve of antithrombotic or antiplatelet therapy were studied. Baseline CRP, P-selectin, sTM and TAT levels were compared to those of 20 matched-healthy subjects in sinus rhythm. AF patients had significantly higher plasma CRP (10.5 ± 2.2 vs 3.25 ± 0.3 mg/l, p = 0.001), P-selectin (219 ± 141 vs 126 ng/ml, p = 0.01), and TAT (54 ± 237 vs 2.7 ± 3.3 ng/l, p = 0.001) levels compared with controls. Soluble TM levels, although higher than controls, did not reach statistical significance. Multivariate regression analyses showed that elevated CRP (OR = 4.8, p = 0.02) and sTM (OR = 1.05, p = 0.04) were the only two predictors of lack of sinus rhythm at 1 year follow-up. An altered inflammatory, haemostatic, endothelial and platelet environment exists in newly diagnosed AF patients. CRP and sTM levels might be used as biochemical markers to predict the status of cardiac rhythm at 1 year follow-up in some AF patients.

The predictive value of cardiac biomarkers in prognosis and risk stratification of patients with atrial fibrillation

PURPOSE OF REVIEW

Atrial fibrillation is a significant public health issue considering its high prevalence in the general population, and is associated with an increased risk of cardiovascular mortality and morbidity and thrombo-embolic complications.Asymptomatic paroxysms of atrial fibrillation occur frequently in the first stages of the disease but patients present to the doctor at a relatively late stage when the associated complications have already taken place. It is crucial to identify such patients as early as possible in order to start preventive therapy. Clinical diagnostic tests to identify patients prone to atrial fibrillation complications have not yet been developed as the exact mechanism and substrate of subclinical atrial fibrillation are not known. Further research is necessary to understand the pathophysiology of subclinical atrial fibrillation and to identify potential risk markers that determine the development and prognosis of the disease.

RECENT FINDINGS

Biomarkers have recently been identified which have been shown to be related to the incidence of atrial fibrillation and its prognosis. They reflect inflammation, neurohumoral activation and subclinical heart damage.

SUMMARY

New biomarkers may help to understand the mechanisms of subclinical atrial fibrillation and signal the likelihood of disease progression. Such biomarkers, though subject to further validation, may be of value in predicting the prognosis and guiding the treatment of patients with atrial fibrillation. They may enhance the ability of risk scores to guide anticoagulant treatment strategies.

Persistent atrial fibrillation is not associated with thrombomodulin level increase in efficiently anticoagulated patients

INTRODUCTION

Atrial fibrillation (AF) is the most common arrhythmia and leads to a five-fold increased risk of stroke compared to persons with sinus rhythm. A soluble form of thrombomodulin (sTM) is a recognized marker of endothelial dysfunction and may contribute to the hypercoagulable state in AF. The aim of the study was to evaluate plasma concentration of sTM in persistent AF patients before and after sinus rhythm recovery following direct current cardioversion (CV).

MATERIAL AND METHODS

In 45 effectively anticoagulated consecutive patients, with persistent non-valvular AF, and normal left ventricular function, CV was performed. Blood samples for sTM assessment were collected twice: 24 hours before and 24 hours after CV.

RESULTS

In 43 patients sinus rhythm was obtained. The mean plasma sTM level was significantly lower in AF patients compared to the control group with sinus rhythm and without anticoagulation (38.5 ±9.9 ng/ml vs. 44.1 ±9.1 ng/ml, p = 0.04). Plasma sTM levels did not change 24 hours after successful CV (36.7 ±9.5 ng/ml vs. 38.5 ±9.9 ng/ml, p = 0.16).

CONCLUSIONS

Plasma sTM concentration was lower in patients with persistent AF and normal left ventricle systolic function than in patients with sinus rhythm, presumably due to chronic oral anticoagulant therapy in the AF group. CV has no impact on sTM plasma level evaluated 24 hours after sinus rhythm restoration.