Assessing Rejection in Heart Patients.

• Position: ORGAN TRANSPLANTS

A new method of assessing organ rejection in heart transplant patients is more effective at estimating the probability of rejection than current practices, a finding that may improve the precision of the diagnosis and reduce overtreating patents with post-transplant medications.

The research was presented by Luciano Potena of Bologna University Hospital, Italy, at the annual International Society for Heart and Lung Transplantation meeting.

Physicians routinely biopsy heart transplant patients to monitor for rejection, which in current practice is diagnosed by histology-based grading. The grading consists of descriptive categories that rely on pathologists' interpretation, requiring them to describe the degree of tissue damage and infiltration by inflammatory cells.

The new method, based on gene expression profiling (GEP) techniques, foregoes descriptive histology and, instead, allows for analysis of genes that are active in the tissue. The analysis of GEP is based on patented technology called MMDx (Molecular Microscope Diagnostic System), which initially was developed for kidney transplantation, and now is being validated in heart, lung, and liver transplantation. MMDx algorithms have been developed based on graft function and outcomes by using machine learning--and reveal how cells are functioning, not how they look.

'Try to ask four poets to describe the same landscape. You'll obtain four different descriptions of the truth, which may be artistically intriguing, but would be difficult to interpret if you need to make technical decisions based on those descriptions," says Potena. 'This new research will help us provide a more-accurate diagnosis of rejection."

The current ISHLT grading system, adopted in 2006, provides categories of rejection severity, both for cellular and antibody-mediated rejection. It describes the degree of tissue damage and infiltration by inflammatory cells and relies on the concept that the larger the infiltrate, the worse the rejection. The purpose of the...