Last reviewed and revised by Faculty of Harvard Medical School on December 20, 2010
By Thomas H. Lee, M.D.
Brigham and Women's Hospital
Doctors have a new way to help diagnose coronary artery disease. It's an ultra-fast CT scan.
Older CT scans could detect calcium deposits in the arteries, usually a sign of some narrowing. But they couldn't tell how much blockage there was inside the arteries.
The newer machines, called "64-slice CT scanners, collect so much information at once that they can nearly "freeze" the beating heart. With older CT scanners, the collection of information took longer and, as a result, the heart was blurred because it moves as it beats. There was too much motion to get a good look inside the arteries of the heart, which are about the thickness of a ball point pen refill.
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Accurate and Less Risky
With the new scanners, however, physicians usually can get an excellent picture of the inside of your coronary arteries good enough to tell you if you have significant blockages. They are not perfect
but they are really, really good. These CT scans are almost as accurate as having coronary angiography with a thin tube (catheter) inserted into your arteries, but they do not carry the same risk of heart attack or stroke.
Many experts believe that these 64-slice scanners are going to revolutionize cardiology care, and they are probably right. Many patients who currently undergo coronary angiography now will be able to avoid the pain and risk of that test. People with acute chest pain who come to the emergency department may go directly into the scanner, to determine right away whether or not they have coronary disease.
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Costs and Excess Use
But, as is true with any new technology, there is real potential for it being used too much. People with mild symptoms only vaguely suggestive of heart disease may get scanned whereas in the past, physicians might have just reassured them, or perhaps ordered an exercise test. Or scans may be performed on people who have no symptoms at all, but are worried about heart disease.
It would be one thing if these scans were free or had no risk. But they will cost several hundred dollars or more, and they do involve a significant amount of radiation exposure to patients. In addition, the "dye" used to visualize the arteries can cause kidney damage.
There is also a real chance that minor abnormalities of coronary arteries will be seen, and that people won't be able to relax about them until they undergo coronary angioplasty or even bypass surgery. These procedures may lead to complications that wouldn't have occurred if the abnormalities never had been seen.
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Don't Schedule One Yet
So the bottom line is that these new scans are simply marvelous technologies but it is going to take a little time for physicians to figure out how they should be used. Right now, no one can tell you for sure whether the benefits outweigh the potential harm for you. Eventually, we will figure this out, and guidelines will specify which patients should undergo this test. The answer is unlikely to be "everyone."
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Thomas H. Lee, M.D. is the chief executive officer for Partners Community HealthCare Inc. He is a professor of medicine at Harvard Medical School. He is an internist and cardiologist at Brigham and Women's Hospital. Dr. Lee is the chairman of the Cardiovascular Measurement Assessment Panel of the National Committee for Quality Assurance.