Abstract P122: Characterization of Ventricular Assist Device Mediated Sensitization in the Bridge to Heart Transplant Patient

Abstract

Purpose: To clarify patterns of anti-HLA antibody expression (sensitization) occurring in patients bridged to transplantation (BTT) with ventricular assist devices (VADs). Methods: The study is a retrospective review of 68 patients undergoing BTT with either Heartmate II (HMII) axial flow LVAD or paracorporal BIVAD from January 2007 to July 2010 at UCLA Medical Center. Results: Five of 15 (33.3%) HMII pts became sensitized during treatment compared to 29 of 53 (54.7%) BIVAD patients, p=0.24. Table 1 shows common etiologies for patient sensitization of which only PRBC transfusion was statistically significant. [ table 1 ] Multiple variable analysis comparing BIVAD vs. HMII while controlling for previous cardiac surgery, pregnancy, and PRBC transfusion demonstrated an Odds Ratio of 5.20, p=0.029 (robust variance estimator). Of sensitized patients, all 5 (100%) of the HMII patients had pre-existing antibodies prior to VAD placement compared to 11 of 29 (62.1%) BIVAD patients, p=0.016. Maximum cumulative MFIs for BIVAD were 46,259 ± 66,349 vs. 42540 ± 12840 for HMII, p=0.90. Time to maximum antibody expression was shorter for the HMII group (34 ± 28 days vs. 5.8 ± 9 days, p=0.04). Table 1. Sensitization Risk Factors Antibodies + Antibodies − p-value Previous Cardiac Surgery 23.5% 8.8% 0.19 Pregnancy 20.6% 2.9% 0.05 PRBC 52.1±34.7 35.9±22.3 0.04 FFP 29.4±14.4 23.6±15.2 0.15 Platelets 9.8±9.7 6.8±6.7 0.20 Cryoprecipitate 3.2±2.6 3.1±2.6 0.74 Blood products expressed as mean units ± std dev Conclusion: BIVADs were associated with a five fold increased risk for sensitization when accounting for other risk factors. HMII patients required pre-sensitization to express antibodies during their treatment interval whereas BIVAD patients developed de novo antibodies. Although the peak cumulative MFIs were similar for both VAD types, the days to reach this peak were significantly less in the HMII group. These data suggest that sensitization in HMII patients may not be due to antigenic stimulation from the device itself.