Characterization of Von Willebrand Factor Multimer Structure in Patients With Severe Aortic Stenosis.

Acquired von Willebrand syndrome (AVWS) associated with severe aortic stenosis (AS) has been frequently subclassified into a subtype 2A based on the deficiency of high-molecular-weight (HMW) multimers as it is seen in inherited von Willebrand disease (VWD) type 2A. However, the multimeric phenotype of VWD type 2A does not only include an HMW deficiency but also a decrease in intermediate-molecular-weight (IMW) multimers and an abnormal inner triplet band pattern. These additional characteristics have not been evaluated in AVWS associated with severe AS. Therefore, we recruited N = 31 consecutive patients with severe AS and performed a high-resolution Western blot with densitometrical band quantification to characterize the von Willebrand factor (VWF) multimeric structure and reevaluate the AVWS subtype classification. Study patients showed an isolated HMW VWF multimer deficiency without additional abnormalities of the IMW portions and the inner triplet structure in 65%. In conclusion, the multimeric pattern of AVWS associated with severe AS does neither resemble that seen in AVWS type 2A nor that seen in inherited VWD type 2A. Therefore, a subclassification into a type 2A should not be used.