LAUSR

OBJECTIVES Low von Willebrand factor (VWF) increases the risk of bleeding. The objective was to assess the influence of VWF on bleeding after valvular surgery. METHODS We studied 82 consecutive patients in median age of 65.5 years with severe isolated aortic stenosis (AS, n = 62) or mitral stenosis (MS, n = 20), undergoing heart valve surgery in extracorporeal circulation. Preoperatively, we assessed VWF antigen (VWF:Ag) and activity (VWF:RCo), a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), and fibrinolysis inhibitors. RESULTS Compared with AS, MS patients were more frequently female (80 vs. 55%, p = 0.045) with atrial fibrillation (AF) (80 vs. 8%, p < 0.0001), with no difference in age or comorbidities. Median postoperative drainage was 420 ml for AS, and 425 ml for MS (p = 0.37). Patients with AS had lower VWF:RCo (125.8 [88.5-160.8] vs. 188.0 [140.3-207.3] IU/dl, p = 0.003) and VWF:Ag (135.8 [112.0-171.2] vs. 191.7 [147.3-236.4] IU/dl, p = 0.01) than MS patients. Mean VWF:RCo/Ag ratio was 0.88 ± 0.17, with no intergroup differences. ADAMTS13 levels and activity were similar in both groups. In AS, both VWF:RCo and VWF:Ag correlated inversely with maximal (r = -0.39, p = 0.0003 and r = -0.39, p = 0.0004, respectively) and mean (r = -0.40, p = 0.0004 and r = -0.39, p = 0.0006, respectively) transvalvular pressure gradients. There was no difference in perioperative bleeding between patients following mitral and aortic valve surgery, and bleeding was not associated with VWF:Ag or VWF:RCo. CONCLUSIONS In severe AS, VWF levels and activity correlate inversely with transvalvular pressure gradients, and are lower than in severe degenerative MS, but do not affect blood loss after valvular surgery in extracorporeal circulation.