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CHICAGO – Scientists may be one step closer to a simple
blood test that could diagnose coronary artery disease (CAD),
according to data reported today by researchers from Duke
University Medical Center.

The scientists, reporting at the annual meeting of the
American College of Cardiology, say they have identified a
small handful of genes in circulating blood that can not only
identify the presence of coronary artery disease, but also
reveal how advanced the disease may be. It is estimated that
some 15 million people in the U.S. have coronary artery
disease.

Currently, diagnosing CAD can be a long and complex process,
often involving multiple electrocardiograms, echocardiograms
and stress tests. Even if all of the tests suggest the presence
of CAD, the full extent of the problem isn't fully known until
a patient undergoes angiography. Angiography is an invasive
procedure that involves inserting a catheter into the coronary
arteries to determine the extent of blockage, or stenosis.

"A blood test would potentially be a lot cheaper and
easier," says Dr. William Kraus, a cardiologist at Duke and the
senior author of the study. "In addition, our study shows that
the activity of these genes is proportional to the extent of
the disease. That means that a blood test based on these genes
could not only tell us if someone has CAD, but also how bad the
problem really is."

Kraus says patients who receive a positive blood test might
be able to short-circuit additional preliminary evaluations and
head directly to coronary catheterization, where any blockages
could be treated.

The investigators, working with colleagues at the Helios
Heart Center in Germany and at CardioDx, a biotechnology
company in Palo Alto, California, that is funding the research,
used whole genome microarray analysis to compare the genes of
41 patients who had undergone coronary catheterization.
Twenty-seven of the patients had blockages or narrowing of
their arteries, and 14 did not.

Scientists identified 526 genes that behaved very
differently between the two groups. Through additional tests
and analysis, they were able to narrow that number to just 11
genes, that when analyzed in a second, independent
catheterization group at Duke, were able to differentiate
between which patients had clinically significant coronary
artery disease and which did not.

"We believe this set of genes is exquisitely sensitive to a
number of inflammatory changes that occur when plaque is
building up in arterial walls," says Kraus. Kraus says the
genes carry tell-tale signs of those changes as they circulate
throughout the body, making them useful sentinels of
disease.

Investigators say additional work already under way may
yield even more genes that could form the basis of a blood test
for clinically important CAD.

CardioDX, in collaboration with eight clinical centers
including Duke, is also conducting a prospective clinical study
designed to validate the set of 11 genes in a larger
population.