New genetic test monitors heart transplant rejection

April 27, 2010, 1:01 a.m.

Stanford researchers published findings from a clinical trial that may lead to a reduction in biopsies to monitor rejection in heart transplant patients.

The study compared rates of rejection and other complications between two cohorts of transplant patients: one undergoing biopsy monitoring and the other undergoing a combination of the genetic test and echocardiogram imaging. The rates of rejection, death, re-transplantation and other primary complications were slightly lower in the genetic testing group (14.5 percent) than those in the biopsy group (15.3 percent).

“The major finding is that a noninvasive approach to the monitoring of heart transplant patients for rejection is not inferior to an endomyocardial biopsy approach that has been in place for nearly 30 years,” said Hannah Valantine, a professor of cardiovascular medicine and the chair of the study.

The results of the study indicate that the two tests are comparable in effectiveness and that the new genetic test could, in many cases, possibly replace the biopsy monitoring that many patients fear and find uncomfortable.

“Heart biopsies can be reduced by a quarter of what’s performed currently using a combination of this new blood test with the echocardiography,” Valantine said. “That can be done safely without any risks to the patient.”

The 602 patients studied had had their transplants six months to five years before the study and were characterized by a lower risk of rejection. The conclusions of the study are limited to this low-risk group, posing the question of whether or not investigators need to further study its relevance in higher risk groups.

Heart transplant patients can “reject” their donated heart if their immune system, even under immunosuppressant drugs, attacks the organ as a foreign object, as it would attack a foreign pathogen. This episode of rejection can compromise the transplant’s effectiveness and have major complications.

Currently, to ensure that rejection is not occurring, doctors take a biopsy of a patient’s heart muscle and examine it under a microscope. To get the tissue, doctors insert a catheter through a vein in the groin or neck and travel down to the heart to collect the tissue. Complications happen in fewer than one percent of these invasive procedures.

The new genetic test utilizes biomarkers — in this case, the activity of 11 different genes — to determine the risk that the body is rejecting the organ.

“There are many biomarkers out there for a whole number of things,” Valantine said. “It is very rare to want to do this type of clinical trial that asks the question of the relevance of the biomarker to the management of patients.”

Patients also fear the biopsy procedure, and Valantine explained that their satisfaction, which the study also monitored, significantly improved with the genetic treatment as opposed to the biopsy.

The trial, called Invasive Monitoring Attenuation through Gene Expression (IMAGE), was conducted at 13 heart transplant centers across the country from 2005 to 2009. The findings were published in the New England Journal of Medicine on Thursday.

An Le Nguyen contributed to this report.

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