Paroxysmal atrial fibrillation: changes in factor VIII and von Willebrand factor impose early hypercoagulability

Cytotoxic CD8+ T Cells Are Involved in the Thrombo-Inflammatory Response during First-Diagnosed Atrial Fibrillation

BACKGROUND

Atrial myopathy and atrial fibrillation (AF) accompany thrombo-inflammation. This facilitates disease progression and promotes major adverse cardiovascular events (MACEs). Thrombin receptor (protease-activated receptor 1, PAR1) signalling is central in mediating thrombo-inflammation. We hypothesised that PAR1 signalling links coagulation and inflammation through cytotoxic CD8⁺ T lymphocytes in patients presenting with first-diagnosed AF (FDAF).

METHODS

A total of 210 patients were studied. We included data and blood samples from patients presenting with FDAF (n = 160), cardiac tissue from patients with paroxysmal AF (n = 32) and 20 controls.

RESULTS

During early AF, a pro-inflammatory and cytotoxic subset of T lymphocytes (CD8⁺) circulated more frequently when compared to patients with chronic cardiovascular disease but without AF, accompanied by elevated plasma levels of CD8⁺ effector molecules, which corresponded to biomarkers of adverse cardiac remodelling and atrial dysfunction. Activation of tissue factor (TF) and PAR1 was associated with pro-inflammatory and cytotoxic effector functions. PAR1-related CD8⁺ cell activation was more frequent in FDAF patients that experienced a MACE.

CONCLUSIONS

In patients with FDAF, the TF-factor Xa-factor IIa-axis contributes to thrombo-inflammation via PAR1 in CD8⁺ T cells. Intervening in this cascade might be a promising synergistic approach to reducing disease progression and the vascular complications of AF.

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.

Prevalence and determinants of atrial fibrillation progression in paroxysmal atrial fibrillation

OBJECTIVE

Atrial fibrillation (AF) often progresses from paroxysmal AF (PAF) to more permanent forms. To improve personalised medicine, we aim to develop a new AF progression risk prediction model in patients with PAF.

METHODS

In this interim-analysis of the Reappraisal of AF: Interaction Between HyperCoagulability, Electrical Remodelling, and Vascular Destabilisation in the Progression of AF study, patients with PAF undergoing extensive phenotyping at baseline and continuous rhythm monitoring during follow-up of ≥1 year were analysed. AF progression was defined as (1) progression to persistent or permanent AF or (2) progression of PAF with >3% burden increase. Multivariable analysis was done to identify predictors of AF progression.

RESULTS

Mean age was 65 (58-71) years, 179 (43%) were female. Follow-up was 2.2 (1.6-2.8) years, 51 of 417 patients (5.5%/year) showed AF progression. Multivariable analysis identified, PR interval, impaired left atrial function, mitral valve regurgitation and waist circumference to be associated with AF progression. Adding blood biomarkers improved the model (C-statistic from 0.709 to 0.830) and showed male sex, lower levels of factor XIIa:C1-esterase inhibitor and tissue factor pathway inhibitor, and higher levels of N-terminal pro-brain natriuretic peptide, proprotein convertase subtilisin/kexin type 9 and peptidoglycan recognition protein 1 were associated with AF progression.

CONCLUSION

In patients with PAF, AF progression occurred in 5.5%/year. Predictors for progression included markers for atrial remodelling, sex, mitral valve regurgitation, waist circumference and biomarkers associated with coagulation, inflammation, cardiomyocyte stretch and atherosclerosis. These prediction models may help to determine risk of AF progression and treatment targets, but validation is needed.

TRIAL REGISTRATION NUMBER

NCT02726698.

Paroxysmal Atrial Fibrillation in Horses: Pathophysiology, Diagnostics and Clinical Aspects

Atrial fibrillation (AF) is the most common arrhythmia in horses causing poor performance. As in humans, the condition can be intermittent in nature, known as paroxysmal atrial fibrillation (pAF). This review covers the literature relating to pAF in horses and includes references to the human literature to compare pathophysiology, clinical presentation, diagnostic tools and treatment. The arrhythmia is diagnosed by auscultation and electrocardiography (ECG), and clinical signs can vary from sudden loss of racing performance to reduced fitness or no signs at all. If left untreated, pAF may promote electrical, functional and structural remodeling of the myocardium, thus creating a substrate that is able to maintain the arrhythmia, which over time may progress into permanent AF. Long-term ECG monitoring is essential for diagnosing the condition and fully understanding the duration and frequency of pAF episodes. The potential to adapt human cardiac monitoring systems and computational ECG analysis is therefore of interest and may benefit future diagnostic tools in equine medicine.

Relationship between Serum FGF21 and vWF Expression and Carotid Atherosclerosis in Elderly Patients with Hypertension

Cardiovascular (CV) and cerebrovascular (CBV) diseases are common in the elderly and cause severe damage, with high morbidity, disability, and mortality. Hypertension, as a risk factor for a variety of CV and CBV diseases, also affects many elderly patients. This study aimed to investigate the relationship between serum FGF21 and vWF expression and carotid atherosclerosis (CAS) in elderly patients with hypertension. We recruited 143 elderly hypertensive patients admitted to our hospital from July 2017 to November 2019 to this study, including 75 patients with comorbid CAS (the observation group, OG) and 68 patients without CAS (the control group, CG). Enzyme-linked immunosorbent assay (ELISA) was used to test serum expression levels of FGF21 and vWF; receiver operating characteristic (ROC) curves to evaluate the value of FGF21 and vWF in diagnosing CAS and predicting the 6-month prognosis in elderly hypertensive patients; Pearson's correlation analysis to analyze the correlation of FGF21/vWF with the plaque thickness and stenosis area in hypertensive patients with CAS. The incidence of CV and CBV events was markedly higher in the high FGF21/vWF group than in the low FGF21/vWF group. Patients from OG were divided into the high FGF21/vWF group and the low FGF21/vWF group based on the median expression level of FGF21/vWF, then the incidence of cardiovascular (CV) and cerebrovascular (CBV) events was compared between the high and low expression groups. Serum levels of FGF21 and vWF were markedly higher in patients from OG than in patients from CG. Both FGF21 and vWF were in positive correlation with the plaque thickness and stenosis area in patients from OG. The area under the ROC curve (AUC) for diagnosing CAS was 0.790 by FGF21 and 0.807 by vWF; the AUC for predicting the occurrence of CV and CBV events was 0.771 by FGF21 and 0.754 by vWF. Serum levels of FGF21 and vWF are increased in elderly patients with hypertension and comorbid CAS, so they can be used for diagnosing CAS and predicting prognosis.