Unexpectedly High Prevalence of Acquired von Willebrand Syndrome in Patients with Severe Aortic Stenosis as Evaluated with a Novel Large Multimer Index

Aim: Severe gastrointestinal bleeding sometimes occurs in patients with aortic stenosis (AS), known as Heyde's syndrome. This syndrome is thought to be caused by acquired von Willebrand syndrome and is characterized by reduced large von Willebrand factor (vWF) multimers. However, the relationship between the severity of AS and loss of large vWF multimers is unclear. Methods: We examined 31 consecutive patients with severe AS. Quantitative evaluation for loss of large vWF multimers was performed using the conventional large vWF ratio and novel large vWF multimer index. This novel index was defined as the ratio of large multimers of patients to those of controls. Results: Loss of large vWF multimers, defined as the large vWF multimer index <80%, was detected in 21 patients (67.7%). The large vWF multimer ratio and the large vWF multimer index were inversely correlated with the peak aortic gradient (R = -0.58, p=0.0007, and R= -0.64, p<0.0001, respectively). Anemia defined as hemoglobin <9.0 g/dl was observed in 12 patients (38.7%), who were regarded as Heyde's syndrome. Aortic valve replacement was performed in 7 of these patients, resulting in the improvement of anemia in all patients from a hemoglobin concentration of 7.5 +/- 1.0 g/dl preoperatively to 12.4 +/- 1.3 g/dl postoperatively (p<0.0001). Conclusions: Acquired von Willebrand syndrome may be a differential diagnosis in patients with AS with anemia. The prevalence of AS-associated acquired von Willebrand syndrome is higher than anticipated.