FOR RELEASE: 1:45 p.m. CT, ThursdayMarch 1, 2001
CONTACT:Darcy Spitz or Carole BullockAHA News Media RelationsSan Antonio Marriott RivercenterPh. (210) 554-6255
Abstract P25
American Heart Association meeting report: Calcium scan predicts heart attack risk in physically fit people
SAN ANTONIO, March 1 -- An electron beam computed tomography (EBCT) scan was able to identify individuals at elevated risk for a heart attack who did not fit the usual high-risk profile, according to a study presented today at the American Heart Association's 41st Annual Conference on Cardiovascular Disease Epidemiology and Prevention.
The research indicates that the scan may identify a risk of heart attack in some apparently healthy adults who don't have the usual risk factors - high cholesterol, smoking, obesity, high blood pressure, physical inactivity, diabetes, or a family history of heart disease.
An EBCT scan, which takes about 90 seconds and costs about $600, detects calcium deposits in the coronary arteries. Atherosclerosis, the process of thickening and hardening of the arteries, starts with the build-up of soft plaque, but as time passes calcium becomes part of the build-up. A higher calcium score may mean more advanced atherosclerosis and a higher risk for future coronary events such as a heart attack.
"For people who are at risk because of a family history of early heart disease, this is an extremely good test to add to a regular physical exam," says Jerel M. Zoltick, M.D., a U.S. Army cardiologist and consultant with the Office of the Surgeon General. It can be useful as part of a cardiovascular screening program.
"The test has a correlation with standard risk factors in that the more risk factors you have, the higher your calcium score. However, there is a tremendous amount of variability among individuals and their tendency to develop coronary disease. Along with the standard risk factors, EBCT helps us to define a person's cardiovascular disease status," says Zoltick.
The researchers used the scan on 436 students in the U.S. Army War College in Carlisle, Penn. The students, average age 43, were considered to be very fit individuals. Participants were given extensive cardiovascular and fitness evaluations including medical, fitness and nutritional histories, lipid profiles and fasting blood sugar levels. The students also underwent physical examination, resting electrocardiogram, treadmill tests and measurements of maximal oxygen consumption.
Calcium scores ranged from 0 to 2112 and were classified into four standard categories. Those with a score of 10 or less had insignificant atherosclerosis, those with scores of 10-99 had mild atherosclerosis, while calcium scores of 100-399 were considered moderate atherosclerosis, and a score of 400 or above was considered to be advanced atherosclerosis.
A low calcium score doesn't necessarily rule out atherosclerosis because the soft plaque in the artery that has not yet calcified is not detected by EBCT. The test results for the students showed that 83.3 percent had insignificant atherosclerosis. Another 13.5 percent had mild atherosclerosis and 1.6 percent had moderate atherosclerosis.
Seven of the students, or 1.6 percent, were found to have advanced atherosclerosis. Four of the seven had calcium scores higher than 1000 and within six months, two of them had heart attacks despite normal treadmill tests.
"In this group, traditional exercise stress tests were not predictive of a coronary event," Zoltick says. "We were surprised by the high scores in a group that was very physically fit and had undergone routine physical examinations."
Individuals with high total cholesterol and those with high low-density lipoprotein (LDL) levels - both risk factors for heart attack - tended to have high calcium levels. However, there was some variance; not all of the students who had high calcium levels also had high cholesterol levels.
There was little or no correlation between calcium levels and fitness as determined by strength measurements, aerobic capacity or body fat, the researchers report.
Individuals with a family history of early coronary artery disease tended to have coronary artery calcification, but there was a wide variation in the calcium scores, Zoltick says.
"For individuals with risk factors or a family history of coronary heart disease this test can be useful in determining the level of risk and what further tests or treatment options to consider," Zoltick says. "However, for people who are at very low risk with no family history of heart disease the benefits of the EBCT may be limited."
The American Heart Association and the American College of Cardiology published a consensus statement in July 2000 concerning the use of EBCT. The writing group stated that by detecting calcium deposits in the coronary arteries, EBCT may help guide appropriate treatment for patients with coronary artery disease. However, at the time the statement was released, the scientists said there was not enough compelling evidence to warrant widespread use of the scan.
Other researchers include Irwin M. Feuerstein, M.D.; Michael P. Brazaitis, M.D.; Mark A. Vaitkus, Ph.D.; and William F. Barko, M.D.
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NR01 - 1255 (Epi/Zoltick)Media Advisory: Dr. Zoltick can be reached at (703) 692-0965. His fax is (703) 692-6118. (Please do not publish contact information.)
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