BACKGROUND: Mitral valve regurgitation is associated with an acquired hemostatic 
defect.
OBJECTIVE: We sought to assess the prevalence and severity of acquired von 
Willebrand syndrome in patients with native valve mitral regurgitation (MR).
PATIENTS/METHODS: Fifty-three patients were prospectively observed with bleeding 
questionnaires and laboratory tests when undergoing an echocardiographic 
assessment of MR. In patients referred for mitral valve surgery, testing was 
repeated postoperatively.
RESULTS: Echocardiography identified 13 patients with mild MR, 14 with moderate 
MR, and 26 with severe MR. Among patients with mild, moderate or severe MR, loss 
of the highest molecular weight von Willebrand factor (VWF) multimers occurred 
in 8%, 64%, and 85%, respectively, median platelet function analyzer collagen 
ADP closure times (PFA-CADPs) were 84 s (interquartile range [IQR] 73-96 s), 156 
s (IQR 104-181 s), and 190 s (IQR 157-279 s), respectively, and the ratios of 
VWF latex activity to antigen were 0.92 (IQR 0.83-0.97), 0.85 (IQR 0.76-0.89), 
and 0.79 (IQR 0.75-0.82), respectively (all P < 0.001). Nine patients reported 
clinically significant bleeding, and seven had intestinal angiodysplasia and 
transfusion-dependent gastrointestinal bleeding (Heyde syndrome), with the 
median number of transfusions required being 20 (IQR 10-33; range 4-50). In 
patients who underwent mitral valve repair (n = 13) or replacement (n = 7), all 
measures of VWF function reported above improved significantly.
CONCLUSION: The high-shear environment of moderate to severe MR is sufficient to 
produce prevalent perturbations in VWF activity. Acquired von Willebrand 
syndrome may occur in this setting, and appears to be reversible with mitral 
valve surgery.