WEDNESDAY, March 5, 2003 (HealthDayNews) -- Stress tests are a helpful tool to figure out if someone has clogged arteries. Just ask talk-show host David Letterman, whose doctors gave him one and discovered he needed an immediate quintuple bypass operation. However, the tests require someone either exert himself or take a drug that simulates physical stress, difficult propositions for the most fragile patients.
Now, a small study suggests doctors could order less-invasive magnetic resonance imaging (MRI) scans instead.
"The interesting aspect is that you may be able to detect significant blockages in the arteries without having to stress the heart," says Dr. Sidney Smith, former president of the American Heart Association and a professor of medicine at the University of North Carolina at Chapel Hill.
Stress tests are common, especially among older patients. Typically, a patient will walk on a treadmill or ride a stationary bicycle to increase the heart rate. The doctor will track the progress of radioactive dye that's been injected into the patient's bloodstream.
As the dye reaches the heart, doctors can use scanning technology to watch what it does. "If a portion of the heart wall isn't receiving enough oxygen, it can't generate the energy it needs to contract and it usually bulbs out," says Dr. John Mazur, a cardiologist at Scripps Mercy Hospital in San Diego. Doctors can then figure out where a blockage is by determining which artery supplies that part of the heart.
Some patients, such as those with arthritis or neurological damage, can't exert themselves through heavy exercise and need to take a drug similar to adrenaline to make their hearts work hard, Mazur says.
While studying the use of MRI scans, researchers in Germany discovered they could detect which parts of the heart aren't receiving enough oxygen without requiring a stress test or a dye injection. The researchers report their findings in the March 5 issue of the Journal of the American College of Cardiology.
The MRI scans picked up magnetic signals from blood that was coming back to the heart to be refilled with oxygen. If there was less deoxygenated blood coming into the heart, the scans showed a darker area, suggesting an artery was blocked down the line.
MRI scans confirmed that researchers could detect problems in the hearts of 16 patients with major artery blockages that had already been diagnosed.
Experts who reviewed the study findings say it's much too early to tell if the MRI scans will supplement or even replace stress tests. However, they add the research deserves further study.
It's possible the fine resolution of MRIs could help doctors detect smaller artery blockages, says Dr. Francis J. Klocke, director of the Feinberg Cardiovascular Research Institute at Northwestern University and author of a commentary that accompanied the journal article.
"The thing is to be settled whether [the MRI] has usefulness, whether it would provide added value," he says. Considering that MRIs can cost $1,000 to $1,500 each, the issue of their value will be important.
More information
Learn more about stress tests from HeartSite.com. And get more information about any heart health issue from the American Heart Association's online encyclopedia.
