P477 Pirche (Predicted Indirectly Recognizable Hla Epitopes) Algorithm as a Possible Predictor of Amr (Antibody Mediated Rejection) Following Heart Transplant, From Lab Experience to Clinical Practice: A Case Report

Abstract

PIRCHE–II is an algorithm used to estimate the risk for developing alloreactivity towards HLA mismatches. A 35–year–old man with idiopathic dilated cardiomyopathy with several previous hospitalizations for heart failure is admitted to our unit for a new episode in August 2021. After evaluation, the patient was placed on the waiting list for transplant. The following month the patient underwent heart transplant. The donor had a compatible CDC crossmatch and was negative for anti–HLA antibodies. After 46 days, the patient was discharged at home in stable conditions after 2 negative endomyocardial biopsies (EMB): ISHLT’04 0. In January 2021, the patient was newly admitted for dyspnea and oliguria. Imaging revealed bilateral severe pleural effusion, biventricular cardiac disfunction; EMB showed acute rejection (ISHLT’04 3R). Panel–reactive antibody (PRA) screening found 93 % of class I PRA, 3 % of class II PRA with IgM and IgG donor–specific antibodies (DSA), C1q–positive. After 2 months, the patient was placed again on the transplant waitlist for a persistent severe biventricular disfunction, massive tricuspid regurgitation and diffuse myocardial fibrosis; class I PRA was decreasing (41 % in March 2022, 31 % in April 2022). Unfortunately, the patient died of infection before re–transplantation. After the event, which was recognized as AMR caused by class I DSA, a form rarely described in literature, we employed the PIRCHE (Predicted Indirectly Recognizable HLA Epitopes) algorithm to predict indirect donor–recipient alloreactivity: PIRCHE–II was 54. Is a high PIRCHE–II score a reliable predictor of AMR following heart transplant? More data and deeper understanding is surely needed. A correct after–transplant serologic monitoring is definitely needed to search for de–novo DSA.