Individual Variability in von Willebrand Factor Fragility in Response to Shear Stress: A Possible Clue for Predicting...

Area of Science:

• Cardiovascular Medicine
• Hematology
• Biomaterials Science

Background:

• Acquired von Willebrand syndrome (AVWS) is a significant cause of bleeding in patients with left ventricular assist devices (LVADs).
• The severity of AVWS and associated bleeding complications varies considerably among LVAD recipients.
• Understanding the mechanisms behind this variability is crucial for improving patient outcomes.

Purpose of the Study:

• To investigate individual variability in von Willebrand factor (VWF) fragility as a cause for differing AVWS severity in LVAD patients.
• To assess the correlation between VWF large multimer degradation and shear stress levels compatible with LVAD function.
• To evaluate the potential of VWF multimer analysis under shear stress for predicting bleeding risk in LVAD candidates.

Main Methods:

• Developed a custom shear stressor to generate shear rates (20,000–40,000 s⁻¹) mimicking LVAD-induced stress.
• Collected whole-blood samples and subjected them to controlled shear stress.
• Quantified the degradation of VWF large multimers using the VWF large multimer index.

Main Results:

• A significant inverse correlation was found between the VWF large multimer index and increasing shear rates (P < 0.0001).
• Experimental VWF degradation levels aligned with those observed in LVAD patients (median 28.9%).
• Individual variations in VWF response to shear stress were evident, suggesting differential fragility.

Conclusions:

• Individual VWF fragility, assessed by response to shear stress, contributes to the variable severity of AVWS in LVAD patients.
• The novel shear stress assay and VWF multimer analysis show promise for predicting bleeding risk prior to LVAD implantation.
• This approach may enable personalized risk assessment and management strategies for LVAD recipients.