Blood test detects early heart transplant rejection without surgery

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Test could help reduce disparities among Black patients, who have higher rates of donor rejection

About 2,000 heart transplants are performed each year in the United States, but not all are successful.

A new study,however, might improve those outcomes.

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Researchers have developed a blood test that could help doctors to detect acute heart transplant rejection, which can occur in the early months after a procedure.

“There’s an urgent need for an alternative method to monitor patients for acute heart transplant rejection,” said Sean Agbor-Enoh, study co-author and chief of the National Heart, Lung and Blood Institute’s Laboratory of Applied Precision Omics. The NHLBI is part of the National Institutes of Health,

“We showed in our initial assessment that this ‘liquid biopsy’ is highly sensitive for detecting acute rejection, finding it weeks to months before current clinical tools. This could potentially save lives in the wake of a critical shortage of donor organs,” said Hannah Valantine, senior study author and the former lead investigator of the Laboratory of Organ Transplant Genomics in the Cardiovascular Branch at the NHLBI.

According to a press release, the researchers estimate the test could eliminate up to 80% of invasive heart tissue biopsies used to detect rejection.

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The study was published today in the journal Circulation, a publication of the American Heart Association.

Valantine said the test is also important for addressing serious health disparities. Because Black patients tend to have higher rates of heart transplant rejection and experience poorer transplant outcomes than other groups nationwide, the test could help reduce existing transplant-related health disparities that have persisted for decades.

The test, called the donor-derived cell-free DNA test, tracks DNA markers from the organ donor that appear in the blood of the transplant recipient. Because injured or dying cells from the donor organ release lots of donor DNA fragments into the bloodstream compared to normal cells, higher amounts of donor DNA indicate a higher risk for transplant rejection. The biomarkers can be detected using specialized lab equipment.

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Current tests used to detect heart transplant rejection rely on frequent and painful biopsies of heart tissue. Those biopsies run the risk of damaging the heart and are limited by their invasiveness and reliability.

In the study, the research team collected blood samples from 171 people who had recently undergone a heart transplant at one of five centers in or near the District of Columbia. The sampling included nearly 2,000 cell-free DNA measurements. The population was about 44% Black. The researchers monitored the patients for signs of acute rejection for nearly 18 months using both traditional heart tissue biopsy and the new blood test.

The researchers found the blood test performed better in their study than tissue biopsy, detecting higher amounts of rejection markers and earlier signs of rejection. It also detected more instances of other types of transplant injury that were missed by biopsy, including so-called antibody mediated rejection, one of the deadliest forms of rejection and the hardest to treat and diagnose. The new blood test may be able to detect rejection as early as 28 days after heart transplantation and at least three months before rejection is detectable using heart tissue biopsy.

However, the new test still has limitations. “This test will not completely eliminate the need for invasive procedures, but it can eliminate about 80% of the biopsies currently performed after heart transplant,” said study co-author Palak Shah, a heart disease specialist at Inova Heart and Vascular Institute, Falls Church, Virginia.

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