Non-traditional
tests may be dynamic duo in predicting
Heart problems
This
Article is in Courtesy of
American Heart Association
Oct 02 (American Heart Association) - Partnering
a blood test with an imaging scan may be a better gauge
of whether blocked arteries are about to trigger a heart
attack or stroke. The researchers reported their
results in yesterday's rapid access issue of Circulation:
Journal of the American Heart Association.
C-reactive protein (CRP) is a marker
for inflammation in the blood stream. Calcium deposits in
arteries - measured with computerized axial tomography (CAT)
scan - indicate the level of plaque buildup. High CRP levels
and calcium scores each have been linked with increased
heart disease risk, but routine screenings don't test for
them.
"The exact role of both calcium scores and CRP levels await
more definitive studies, but we have found that their combined
use is predictive of cardiovascular events," says Robert
Detrano, M.D., Ph.D. study coauthor and professor of medicine
at UCLA School of Medicine.
The tests are complementary: coronary
calcium indicates the presence and amount of coronary atherosclerosis,
while CRP suggests that plaque contains inflammatory factors
that make it more prone to rupture and block blood vessels.
"Together they can gauge the presence, the amount and the
stability of artery-clogging plaque," says Detrano.
Recent research has shown elevated CRP levels impart increased
risk of a coronary event, he says. However, it's uncertain
whether elevated levels of either cause risk or are just
an association.
In Detrano's study, researchers examined data from more
than 1,400 people free of heart disease when enrolled. Participants
were part of the South Bay Health Watch, a study of adults
from Los Angeles suburbs. They were 45 years or older with
multiple cardiovascular risk factors, but had not exhibited
symptoms of cardiovascular disease. All had their calcium
and CRP levels measured. Researchers followed 967 of the
people who didn't have diabetes for about six and a half
years. People with diabetes were excluded because calcium
scores have not been shown to predictive.
Fifty people had a heart attack or cardiovascular death
and 104 had a cardiovascular event of some kind in the follow
up. These people also had higher calcium scores and CRP
levels than people who didn't have a cardiovascular event.
Calcium and CRP levels appeared
to be synergistic predictors of cardiovascular events.
Researchers noted a six-fold difference in risk of heart
attack and cardiac death and a seven-fold difference in
the risk of any cardiovascular event between the people
at lowest risk compared to people at highest risk.
"Individuals at intermediate risk may benefit from profiling
based on high sensitivity CRP levels and coronary calcium,
as both factors contribute independently toward the incidence
of cardiovascular events," says Detrano.
However, he adds that the findings are not strong enough
to back widespread screening.
The research didn't address electron
beam computed tomography (EBCT), a popular, but scientifically
unvalidated way to measure coronary calcium.
Coauthors are Robert Park, M.D.; Min Xiang, M.S.; Paul Fu,
Ph.D.; Youhanna Ibrahim, M.D.; Laurie LaBree, M.S.; and
Stanley Azen, Ph.D. The National Heart, Lung and Blood Institute
funded the study.
