Stress Test May Miss Some Heart Disease
Treadmill Tests May Not Catch All Who Have Significant Atherosclerosis
Aug. 17, 2004 -- Using only a stress tests to screen for heart disease may not catch many people who have atherosclerosis, or hardening of the arteries, and are at risk for heart attack or stroke.
A new study suggests that additional testing using computer imaging that looks for calcium deposits on the arteries of the heart may be necessary to determine the level of risk in people with suspected heart disease. Calcium deposits may indicate atherosclerosis.
Researchers found 56% of people who had normal results on their stress tests had calcium scores that put them at increased risk for heart disease, and 31% had scores that placed them at highest risk for heart attack.
"Our findings demonstrate that a relatively high number of patients who had normal readings on their stress tests had a calcium score of greater than 100, a score that is accepted as implying the need for aggressive medical treatment," says researcher Daniel Berman, MD, director of cardiac imaging at Cedars-Sinai Medical Center, in a news release.
Comparing Heart Disease Screening Tests
Stress tests have been widely used for more than 50 years to identify people with heart disease and help direct treatment. In a stress test, heart rate and blood pressure is monitored before, during, and after exercise on a treadmill. It helps determine how much work the heart can take and can help diagnosis heart disease.
In the last 30 years, stress tests done with imaging techniques have become the most common type of stress testing. These tests use a small amount of radioactive material that's injected into the patient during exercise, and the material sends signals to a camera that picks up abnormalities in blood flow to the heart that indicate atherosclerosis.
More recently, computer-assisted imaging tests that use computed tomography (CT) scans have been used to screen for the presence of calcium within the arteries. These tests do not require an injection. Instead, they use special X-ray equipment to get a cross-sectional picture of calcium buildup in the arteries.
The calcium score from these tests represents the patient's risk of future heart-related complications. A score of zero is the best. Scores between 1 and 100 indicate a low level of risk, scores from 100 to 400 indicate an increased risk with treatment recommended, and a score over 400 identifies patients at highest risk for heart attack.