Factors influencing HLA sensitization in implantable LVAD recipients

Abstract

Background: Patients bridged to transplantation (TX) with the implantable left ventricular assist device (LVAD) may be at increased risk for the development of panel-reactive antibodies (PRA) during support.

Methods: To investigate that, we evaluated 60 patients who received the HeartMate LVAD at our institution, of whom 53 had PRA results available for analysis. T lymphocyte PRA levels were examined before LVAD, at the peak PRA level during LVAD support (PEAK), and just before TX. A PRA level more than 10% was considered indicative of sensitization against HLA antigens.

Results: The only factor that had a significant effect on PRA levels before LVAD was patient's sex (1.3% for men versus 7.4% for women; p = 0.005). During LVAD support, peak PRA levels increased significantly and the sex-associated differences were no longer evident (33.3% men, 34.3% women; not significant). At the time of TX, PRAs decreased to 10.9% (men) and 7.0% (women) (not significant). We examined the influence of blood products received before TX on PRA levels. Patients who received less than the median number of total units (<median) had lower peak PRA values (22.3% versus 49.2%; p = 0.01) and TX PRA values (3.5% versus 22.1%; p = 0.02) than those receiving more than the median (>median). When examined by the type of blood product, only the number of platelet transfusions significantly increased the peak PRA (<median: 24% versus >median: 46.9%; p = 0.03). Patients who received blood that was leukocyte-depleted tended to have lower TX PRA levels (2.9%) compared with those who did not (13.9%, p = 0.18). Forty-two patients were successfully bridged to TX, with three early and two late deaths after TX. Whereas 39 patients received transplants without intervention, 3 were treated by plasmapheresis with a 77% reduction in their HLA antibody levels at TX as measured by flow cytometry.

Conclusions: Patients with the implantable LVAD are at significant risk for the development of anti-HLA antibodies during support. Although this sensitization is often transient, intervention using plasmapheresis may be useful for some patients.