# Diagnosis of rejection following heart transplantation: diving into the future

## TL;DR

This paper reviews current and emerging non-invasive methods for detecting heart transplant rejection and highlights the need for multi-modal approaches to improve diagnosis.

## Contribution

The paper emphasizes the limitations of existing non-invasive rejection detection methods and advocates for future research into multi-modal diagnostic strategies.

## Key findings

- Current non-invasive methods for diagnosing heart transplant rejection lack sufficient sensitivity or specificity.
- Emerging techniques like donor-derived cell-free DNA and gene expression profiling show promise but are not yet sufficient alone.
- A multi-modal approach combining non-invasive diagnostics and personalized medicine is recommended for future research.

## Abstract

Since the standardization of the grading system for pathologic diagnosis of antibody-mediated and acute cellular rejection, endomyocardial biopsy has remained the gold-standard. However, biopsies are invasive, costly, and limited by sampling error. As such, adjuvant non-invasive methods including cardiac biomarkers, imaging including cardiac magnetic resonance and echocardiography, and donor-specific antibodies and non-HLA antibodies have been traditionally used. However, all these techniques are limited by either sensitivity or specificity. More recently, there has been a shift to other contemporary non-biopsy surrogate markers for rejection surveillance including donor-derived cell free DNA, gene expression profiling, and messenger RNA and micro-RNA in tissue. Herein we review the methods currently utilized to diagnose rejection and their limitations. We find that while there have been significant advancements in technology and non-invasive techniques, no current method alone adequately diagnoses rejection (Central Image). Thus, future studies are warranted to investigate new strategies involving a multi-modal approach that incorporates non-invasive diagnostic methods and personalized medicine to monitor postoperative progression in heart transplant patients.