Molecular Heterogeneity and Prognostic Implications of Low-Grade Acute Cellular Rejection (1R/1A) in Heart Transplantation

The authors aimed to investigate the molecular and clinical significance of low-grade acute cellular rejection (ISHLT grade 1R/1A) in heart transplantation, questioning whether this histological finding reflects biologically meaningful alloimmune activation and affects prognostic risk. Their study found that while histologic 1R/1A was not associated with graft dysfunction, it correlated with higher levels of circulating biomarkers and an increased risk of subsequent rejection. Importantly, molecular diagnostics revealed a subset of 1R/1A cases with elevated risk for future rejection, suggesting the need for integrating molecular assessments into post-transplant risk stratification.