By Salynn Boyles
WebMD Health News
Reviewed by Louise Chang, MD
Aug. 21, 2012 -- A test that measures calcium deposits in the walls of the blood vessels supplying the heart is better than other tests for identifying patients at risk for heart attack and stroke.
Coronary artery calcium score (CAC) was found to be the most accurate predictor of whether people would suffer one of these events, in a study published today in the Journal of the American Medical Association.
The test is increasingly used by heart doctors to identify heart disease, says cardiologist Gordon Tomaselli, MD, of Johns Hopkins University Medical Center. He was not involved with the study.
"Someone who has calcium in their coronary arteries is no longer at risk for developing heart disease -- they have heart disease," he tells WebMD. "That is why more and more cardiologists are using this test."
28 Million Americans
About 28 million Americans are considered to have an intermediate risk for having a heart attack or stroke, says researcher Joseph Yeboah, MD, of Wake Forest University School of Medicine in Winston-Salem, N.C.
In the study, researchers compared six predictive tests.
In addition to coronary artery calcium imaging, they examined:
- Ankle-brachial index testing, in which blood pressure is measured in the lower leg as well as the arm.
- High-sensitivity C-reactive protein blood testing, which is a measure of inflammation.
- Brachial flow-mediated dilation, in which ultrasound imaging is used to measure blood flow through a major blood vessel in the upper arm.
- Carotid wall thickness imaging, which identifies narrowing of the arteries that supply blood to the brain.
- Assessment of family history.
First Study to Compare Risk Tools
The study included about 1,300 people with heart disease risk factors (except diabetes) who were determined to have an intermediate risk for developing heart disease, based on the widely used prediction model known as the Framingham Risk Score (FRS).
Specifically, the Framingham model determines the probability of having a heart attack, stroke, or other cardiovascular event over the next 10 years.
After having all six of the tests, they were followed for an average of 7 1/2 years.
Coronary artery calcium imaging was the most highly predictive of the six tests evaluated. Family history, ankle-brachial index, and high-sensitivity CRP were also predictive of heart attack and stroke risk.
"This is the first study to examine the predictive value of the current clinical tools for determining risk in patients who fall into this intermediate-risk group," says Yeboah.
But he says that it is too soon to recommend CAC imaging for everyone in this group.
The next step is to confirm that the test leads to better decisions about treatment and better outcomes in the real-world setting, he says.
Tomaselli, who is a past president of the American Heart Association, says new-generation scanners will combine CAC imaging with imaging tests that are routinely used in hospital ERs.
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