August 14, 2009

New technique uses blood test to check for signs of heart transplant rejection

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Mark Wigger, M.D.

New technique uses blood test to check for signs of heart transplant rejection

Rather than undergo an invasive procedure in the catheterization lab, heart transplant patients at Vanderbilt Medical Center now have the option of having a simple blood test to monitor signs of rejection — a technique that is getting favorable reviews from clinicians and patients alike.

AlloMap testing, created by molecular diagnostics company XDx, looks for genes associated with an increased risk of heart rejection, said Mark Wigger, M.D., medical director of the heart transplant program at the Vanderbilt Transplant Center.

Vanderbilt was the first center in the state to use the new monitoring tool.

“This testing modality is now being used throughout the country at 15-20 centers,” said Wigger. “Although this is not a perfect test, it is a rather accurate predictor that there is no presence of ACR (acute cellular rejection) or high-grade rejection.

“The patients absolutely love it,” said Wigger. “It is a much easier process, more comfortable and costs less. It is a quality of life issue. The tests are done every 4-6 months.”

Previously, the only means to monitor rejection was through an endomyocardial biopsy. Traditionally, patients would have more than 20 biopsy procedures during the first year after their heart transplant, eventually tapering down to two or three a year for the rest of their lives.

Recently the FDA approved the use of AlloMap testing in patients who are at least six months post transplant. VTC only allows the new testing on patients who are at least two years post transplantation.

“The risk of rejection is a lot lower two years out, while the risk of complications from a biopsy is higher the further out a patient is from transplant,” said Wigger. “So it’s a calculated risk. I am sure we will begin to move back our time frame, but for now our patients are happy and we are very pleased with the outcomes.”

Wigger anticipates that researchers will identify more genes specifically targeting low-grade rejection in the hope that clinicians will be able to rely on AlloMap testing and resort to biopsy methods under extreme circumstances. In an effort to better serve patients, specialized labs have been opened in Memphis and Knoxville for AlloMap testing.

Vanderbilt recently developed an extensive outreach program in Johnson City, Knoxville and Lebanon with locations in Jackson and Hopkinsville, Ky., in the works.

“There are times when a patient cannot get back to VTC,” said Wigger. “We are able to offer this convenience in their own communities. This way they can stay with their own primary care physician and cardiologist and we provide community physician counseling and guidelines so that the local doctors will have a better understanding of post transplant complications and how we can work together.”

Heart transplants at VTC are seeing a marked increase. There were 22 heart transplants performed during fiscal year 2008, up from 13 in fiscal year 2007.

“We have grown into a coalesced team with good transplant and surgical experience and a nationally recognized advanced heart failure program,” said Wigger. “We have improved and have exceptional patient survival and quality of life outcomes. We are giving patients more options to bridge them to transplant, or some kind of recovery without transplant, through newer technologies.”