Impact of left venticular assist device (LVAD)-mediated humoral sensitization on post-transplant outcomes

Background: Humoral sensitization, defined as a panel-reactive antibody (PRA) screen of > 10%, places heart transplant recipients at a greater risk of acute rejection and mortality. Previous studies have suggested an increased sensitization in left ventricular assist device (LVAD) recipients, although neither the impact of device selection nor the clinical importance of elevated PRA in these patients has been completely described. Methods: Using the registry of the International Society for Heart and Lung Transplantation (JSHLT), we compared PRA levels in 7,686 heart transplant recipients to determine the impact of LVAD therapy on humoral sensitization, acute rejection and mortality. To determine the impact of device selection on sensitization, we compared data from the ISHLT registry as well as from our own institution. Results: Elevated PRA levels were found in 16.6% of LVAD recipients, compared with 7.6% of non-LVAD controls (p < 0.0001). Sensitization differed by device type, being present in 21.9% of Thoratec recipients, 14.4% of HeartMate recipients, and 15.5% of Novacor recipients (P = 0.01). Despite these findings, LVAD use had no impact on rejection rates. LVAD use was associated with a small increase (4.4% and 4.3%, respectively) in 1- and 2-year mortality. Conclusions: These findings support the concept that mechanical circulatory support increases the rate of humoral sensitization. However, these differences in sensitization do not translate to substantial differences in the clinical outcomes of rejection and mortality.