Extracellular vesicles (EVs)-mediated inter-organ communication represents a promising frontier in transplant immunology; however, its role in cardiac allograft rejection remains poorly characterized. We performed proteomic profiling of plasma-derived EVs in a rat heterotopic heart transplantation model. By comparing allogeneic and isogeneic graft recipients to sham-operated controls, we identified significant enrichment of hepatic-specific proteins in circulating EVs during acute rejection, with ATIII emerging as a top candidate.