Acquired von Willebrand syndrome in continuous-flow ventricular assist device recipients

Background: Bleeding is a major cause of morbidity in recipients of continuous-flow left ventricular assist devices (CF-LVAD). A better understanding of the impact of CF-LVAD support on the hemostatic profile is necessary to establish better strategies for anticoagulation therapy and risk assessment for bleeding complications. A prospective multicenter study was conducted to characterize von Willebrand factor (vWF) profiles in patients undergoing CF-LVAD implantation. Methods: Blood samples were collected before and after CF-LVAD implantation from 37 patients between July 2008 and April 2009 at Duke University and the University of Minnesota. Blood samples were analyzed for vWF, platelet and collagen-binding ability. The presence of high-molecular-weight (HMW) vWF multimers were detected through gel electrophoresis, and deficiency was graded on a scale of 0 (normal) to 3 (severe loss). Results: All 37 patients exhibited significant loss of HMW vWF multimers within 30 days of CF-LVAD implantation. Ten of the 37 patients experienced bleeding complications after CF-LVAD placement. Conclusions: All CF-LVAD recipients had acquired von Willebrand syndrome after LVAD placement, demonstrated by reduced or absent HMW vWF multimer levels. However, not all recipients had bleeding complications. These findings suggest that loss of HMW vWF multimers alone cannot predict bleeding risk. Further refinement of laboratory techniques and a larger follow-up is required to identify risk factors for bleeding in CF-LVAD recipients.