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Background: Organ transplant candidates with serum antibodies directed against human leukocyte antigens (HLA) face longer waiting times and higher mortality while awaiting transplantation. This study examined the accuracy of virtual crossmatch, in which recipient HLA-specific antibodies, identified by solid-phase assays, are compared to the prospective donor HLA-type in heart transplantation. Methods: We examined the accuracy of virtual crossmatch in predicting immune compatibility of donors and recipients in heart transplantation and clinical outcomes in immunologically sensitized heart transplant recipients in whom virtual crossmatch was used in allograft allocation. Results: Based on analysis of 257 T-cell antihuman immunoglobulin complement-dependent cytotoxic (AHG-CDC) crossmatch tests, the positive predictive value of virtual crossmatch (the likelihood of an incompatible virtual crossmatch resulting in an incompatible T-cell CDC-AHG crossmatch) was 79%, and the negative predictive value of virtual crossmatch (the likelihood of a compatible virtual crossmatch resulting in a compatible T-cell CDC-AHG crossmatch) was 92%. When used in a cohort of 28 sensitized patients awaiting heart transplantation, 14 received allografts based on a compatible virtual crossmatch alone from donors in geographically distant locations. Compared with the other 14 sensitized patients who underwent transplant after a compatible prospective serologic crossmatch, the rejection rates and survival were similar. Conclusion: Our findings are evidence of the accuracy of virtual crossmatch and its utility in augmenting the opportunities for transplantation of sensitized patients. [Copyright &y& Elsevier]

Left ventricular assist device (LVAD) implantation before heart transplantation has been associated with formation of antibodies directed against human leukocyte antigens (HLA), often referred to as sensitization. This study investigated whether prior sensitization or LVAD type affected the degree of post-implantation sensitization. The records of consecutive HeartMate (HM) I and HM II LVAD patients were reviewed. Panel reactive antibody (PRA) was assessed before LVAD implantation and biweekly thereafter. Sensitization was defined as PRA > 10%, and high-degree sensitization was defined as PRA > 90%. An HM LVAD was implanted in 64 patients, and 11 received a HM II LVAD as a bridge to transplant. Ten HM I patients (16%) were sensitized before LVAD implantation (HM I-S), and 54 (84%) were not (HM I-Non-S). Nine HM I-S patients (90%) became highly sensitized (PRA > 90%) compared with 9 HM I-Non-S patients (16.7%; p < 0.001). The PRA remained elevated (> 90%) in 8 of the 9 (88.9%) highly sensitized HM I-S patients vs 5 of the 9 (55.6%) HM I-Non-S highly sensitized patients. The PRA levels in the rest of the HM I-S highly sensitized patients declined from 93% ± 4% to 55% ± 15% (p = 0.01). Among the 11 HM II patients, 1 (9%) was sensitized before LVAD implantation (PRA, 40%) and the PRA moderately increased to 80%. No other HM II patient became sensitized after implantation. Thus, 1 of 11 (9%) HM II patients became sensitized compared with 29 of 64 (45%) HM I patients (p = 0.04). Pre-sensitized patients are at higher risk for becoming and remaining highly HLA-allosensitized after LVAD implantation. The HeartMate II LVAD appears to cause less sensitization than HeartMate I. [Copyright &y& Elsevier]