Von Willebrand Factor Plasma Levels Variability In Nonvalvular Atrial Fibrillation

N-Terminal Pro B-Type Natriuretic Peptide's Usefulness for Paroxysmal Atrial Fibrillation Detection Among Populations Carrying Cardiovascular Risk Factors

Background: Atrial fibrillation (AF) systematic screening studies have not shown a clear usefulness in stroke prevention, as AF might present as paroxysmal and asymptomatic. This study aims to determine the usefulness of some blood-biomarkers to identify paroxysmal atrial fibrillation in the context of a screening programme. Methods: A total of 100 subjects aged 65-75 years with hypertension and diabetes were randomly selected. AF was assessed by conventional electrocardiogram (ECG) and 4 weeks monitoring with a wearable Holter device (Nuubo™). N-terminal pro B-type natriuretic peptide (NT-proBNP), apolipoprotein CIII (ApoC-III), von Willebrand factor (vWF), ADAMTS13, urokinase plasminogen activator surface receptor (uPAR), and urokinase plasminogen activator (uPA) were determined in serum/plasma samples and the levels were compared depending on AF presence and mode of detection. Results: The AF prevalence in the studied population was found to be 20%. In seven subjects, AF was only detected after 1 month of Holter monitoring (hAF group). NT-proBNP levels were higher in subjects with AF compared with subjects with no AF (p < 0.0001), even when only taking into account the hAF group (p = 0.031). No significant differences were found in the other biomarkers. The NT-proBNP >95 pg/ml cut-off showed high sensitivity and specificity to detect AF (95%, 66.2%) or hAF (85.72%, 66.2%) and was found to be an independent predictor of AF and hAF in a logistic regression analysis. NT-proBNP correlated with AF burden (r = 0.597, p = 0.024). Conclusion: NT-proBNP was elevated in AF cases not identified by ECG; thus, it may be used as a screening biomarker in asymptomatic high-risk populations, with a promising cut-off point of 95 pg/ml that requires further validation.

Prognostic value of von Willebrand factor in patients with atrial fibrillation: A meta-analysis

BACKGROUND

Studies on the prognostic role of von Willebrand factor (vWF) in patients with atrial fibrillation (AF) are conflicting. This meta-analysis aimed to evaluate the association of elevated circulating vWF level with adverse outcomes in patients with AF.

METHODS

PubMed and Embase were used to search literature through August 2017. Prospective observational studies that evaluated the association of elevated vWF level with major adverse cardiac events (MACEs) and all-cause mortality in patients with AF were deemed eligible. The MACEs included death, stroke/transient ischemic attack, heart failure, myocardial infarction, and systemic/peripheral embolism.

RESULTS

A total of 6 studies were included this meta-analysis. Patients with AF with the highest vWF level were independently associated with greater risk of MACEs (risk ratio [RR] 2.20; 95% confidence intervals [CI] 1.61-3.01) and all-cause mortality (RR 1.63; 95% CI 1.39-1.91). Subgroup analysis showed that the prognostic role of higher vWF level was consistently observed in each defined subgroups.

CONCLUSION

Patients with AF with elevated vWF level are independently associated with a higher risk of MACEs and all-cause mortality. However, more well-designed prospective studies are needed to confirm these findings.

Von Willebrand Factor: Multimeric Structure and Functional Activity in Patients With Atrial Fibrillation With and Without Oral Anticoagulation

von Willebrand factor (vWF) is a multimeric glycoprotein present in blood plasma. It is synthesized in megakaryocytes and endothelial cells, secreted into circulation in the form of high-molecular-weight multimers (HMWMs), and cleaved into shorter, less active multimers by ADAMTS13. It is essential for platelet adhesion and aggregation. Previous studies have investigated the relationship between vWF levels and thromboembolic events with little regard to vWF multimeric structure. Patients with atrial fibrillation (AF) exhibit higher plasma vWF and lower ADAMTS13 levels. One hundred seven patients with AF, 51 anticoagulated and 56 nonanticoagulated, were eligible for the study. Plasma samples were analyzed for vWF antigen, vWF activity, and ADAMTS13; vWF multimers were analyzed by Western blot in 1% to 1.3% sodium dodecyl sulfate agarose gel electrophoresis. Patients with AF without oral anticoagulation (OAC) had significantly higher vWF plasma levels (154.00 [75-201] UI/dL) and vWF activity (60.00% [20%-210%]) compared to patients with OAC (133.50 [90-192] UI/dL, P = <.001; 50.00% [20%-160%], P = .02). Both were specially decreased in patients treated with acenocumarin. Patients without OAC also showed lower ADAMTS13 levels and presence of vWF HMWMs. Patients with AF show higher plasma levels and vWF activity. Moreover, treatment with traditional OAC (acenocumarin) significantly reduced vWF levels. Patients without OAC might have an increased risk of thrombotic events showing lower ADAMTS13 and higher vWF levels. Patients with stroke had higher plasma levels, vWF activity, and HMWMs. Our study suggests that increased vWF levels and presence of HMWMs could be related to cerebrovascular disease and may represent useful biomarkers for stroke in AF.