Antibody testing for cardiac antibody-mediated rejection: which panel correlates best with cardiovascular death?

Abstract

Background: Recent efforts are being undertaken to update and refine current diagnostic criteria for antibody-mediated rejection (AMR) in heart transplantation. We believe that the appropriate reactants are those that best predict the adverse consequences of AMR and therefore tested various models using different reactants to find the best predictors of cardiovascular mortality in pathologically defined AMR.

Methods: The study group included only patients in whom all immunofluorescence antibodies of interest had been tested on biopsy specimens obtained after 2002 when C4d was routinely added. We analyzed our data using 3 Cox proportional hazard models with time-varying covariates using an end point of cardiovascular mortality, as previously defined.

Results: In 3,712 biopsy specimens from 422 patients, the 2-antibody model achieved a value of R(2) = 0.930 using C3d and C4d antibodies alone. A model that used 4 antibodies--C3d, C4d, human leukocyte antigen-D related (HLA-DR) and fibrin--was superior (R(2) = 0.988). The model that best predicted cardiovascular mortality included all 6 antibodies: HLA-DR, immunoglobulin (Ig) G, IgM, C3d, C4d, and fibrin (R(2) = 0.989). The models using 4 or 6 antibodies were significantly superior to the model using only C3d and C4d (for each interaction, p < 0.0001).

Conclusions: The combination of complement components, HLA-DR and fibrin, is valuable in defining AMR in patients at risk for allograft loss from cardiovascular causes. Fibrin is particularly important for detecting the presence of severe AMR, with a high likelihood of poor long-term patient outcome.