Association of the von Willebrand Factor–ADAMTS13 Ratio With Incident Cardiovascular Events in Patients With Peripheral Arterial Disease

Background: Platelet adhesion is mediated by von Willebrand factor (vWF), and disintegrin-like and metalloprotease domain with thrombospondin type-1 motif, number 13 (ADAMTS13) is a protease that cleaves vWF. A change in the balance between vWF and ADAMTS13 in favor of thrombosis might occur shortly before ischemic cardiovascular (CV) events. Objective: To determine whether vWF, ADAMTS13, and the ratio of vWF and ADAMTS13 change during the months preceding an acute CV event. Design: Prospective longitudinal observational study. Setting: Outpatient. Patients: A total of 595 participants with peripheral artery disease (PAD). Measurements: Blood samples were obtained every 2 months for up to 3 years and hemostatic factors examined at intervals preceding events. Results: Sixty-one participants (cases) experienced events and were matched to 122 PAD controls. During the 2-month interval prior to an event, cases (n = 48) had higher levels of the vWF and ADAMTS13 than controls (n = 95; P = .05), but significance was lost after adjusting for the baseline differences in myocardial infarction, unstable angina, and stroke. During the 10 months prior to an event, median values for vWF and the ratio of vWF and ADAMTS13 were higher in cases than in controls, but the differences were not statistically significant. However, in a subset of 20 patients with complete bimonthly data, there was a trend toward an increase in the ratio in the 10 months prior to a CV event (P = .04). Conclusion: In patients with PAD experiencing an ischemic CV event, a significant increase in the ratio of vWF to ADAMTS13 prior to the event could not be confirmed, although there was a weak trend in this direction.