What is the clinical evidence from this study?

Study design: Meta-Analysis. Population: Atrial fibrillation (n=4008). Intervention: Elevated von Willebrand factor (vWF) level vs. Lowest category of vWF level. Primary outcome: Major adverse cardiac events (MACEs) (RR 2.20, 95% CI 1.61-3.01).

July 1, 2018Open Access

Prognostic value of von Willebrand factor in patients with atrial fibrillation

Key Result

Elevated von Willebrand factor levels in patients with atrial fibrillation were independently associated with a greater risk of major adverse cardiac events (RR 2.20) and all-cause mortality (RR 1.63).

Study Design

Type

Meta-Analysis (n=4,008)

Structured PICO

Does elevated von Willebrand factor predict major adverse cardiac events and all-cause mortality in patients with atrial fibrillation?

Population

4,008 patients with atrial fibrillation from 6 prospective observational studies, followed for 1.58 to 7.0 years to assess the prognostic value of elevated von Willebrand factor.

Exposure

Highest category of circulating von Willebrand factor (vWF) level

Comparator

Lowest category of circulating von Willebrand factor (vWF) level

Outcome

Major adverse cardiac events (MACEs: death, stroke/transient ischemic attack, heart failure, myocardial infarction, and systemic/peripheral embolism) and all-cause mortalitycomposite

Elevated circulating von Willebrand factor is independently associated with a higher risk of major adverse cardiac events and all-cause mortality in elderly patients with atrial fibrillation.

Main Result

Relative Risk: 2.2 (95% CI 1.61–3.01)

Limitations

Relatively small number of available studies
Substantial heterogeneity across studies in pooling MACEs
Different cutoff values of vWF used across studies to define higher vWF level
Circulating vWF level was only measured at baseline
Lack of adjustment for residual confounding factors such as vWF polymorphisms, systemic inflammation, blood type, and ADAMTS13 activity
Patients analyzed were predominantly elderly, limiting generalizability to younger patients

Abstract

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.

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