MedWire News: A high level of von Willebrand Factor (vWF) is an independent risk factor for mortality and bleeding in patients with atrial fibrillation (AF), research suggests.
The study authors say that vWF levels predict adverse events even in patients who are receiving prophylactic anticoagulation and may therefore be valuable for use in risk stratification.
The conclusions reported by Gregory Lip (City Hospital, Birmingham, UK) and co-workers are based on a large prospective study in which 829 patients with permanent AF, who were on stable oral anticoagulation therapy, were followed-up for 2 years.
At baseline, the mean age of the patients was 76 years, 50% were male, the mean CHADS2 score was 2 (indicating moderate stroke risk), and median D-dimer and vWF levels were 257 IU/dl and 171 IU/dl, respectively. During a median follow-up duration of 828 there were 95 adverse cardiovascular events, 69 deaths, and 68 major bleeding episodes.
For each adverse event, Lip's team constructed receiver-operator characteristic curves that gave a median cutoff point of 221 IU/dl for vWF; there was no cutoff for D-dimer.
Multivariate regression analysis found that high vWF levels were independent predictors for four major endpoints: adverse cardiovascular events (hazard ratio[HR]=2.71), all-cause mortality (HR=2.03), cardiovascular mortality (HR=4.41), and major bleeding (HR=4.47).
Furthermore, adding plasma vWF levels as a risk factor improved the accuracy of two existing risk scores (CHA2DS2-VASc and HAS-BLED) for predicting the risk for stroke and bleeding.
Writing in the Journal of the American College of Cardiology, Lip et al remark: "In this study we showed for the first time how an increased plasma vWF level, an established marker for endothelial damage/dysfunction, is associated with an adverse prognosis in AF patients, with regard to cardiovascular (mainly thrombotic) events, mortality, and bleeding."
They conclude: "This biomarker may potentially be used to refine stroke and bleeding risk-stratification in AF."
In an accompanying editorial subtitled Victor Serebruany (Johns Hopkins University, Towson, Maryland, USA) said the data are "convincing" but stressed that further assessment of vWF in AF patients is "urgently needed to better validate this promising biomarker."
He said: "These intriguing data need to be confirmed in a properly designed and adequately powered randomized trial."
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