Study suggests alternative to invasive heart test
New York: People about to be scanned for suspected heart disease may want to consider a low-radiation, non-invasive test, doctors said Monday.
Dr. Moritz Wyler von Ballmoos of Children`s Hospital Boston, who worked on the study, said low-radiation CT scans compared favorably to standard tests.
"They have a lot to offer because they are less invasive and expose patients to less radiation," he said. "I think it is a very reasonable option for patients."
After reviewing the medical literature, they concluded the test is just as good at ruling out heart problems as the current gold standard, called catheter coronary angiography.
During that procedure, doctors take x-ray pictures of the heart while injecting contrast fluid into it through a slim catheter. The catheter is threaded into the heart via a blood vessel, which sometimes causes bleeding, and in very rare cases, death.
Partly to get around those risks, some patients get a CT, or computed tomography, heart scan instead. The scan is non-invasive, but it exposes people to more x-rays than the catheter-based method.
That extra radiation increases the patients` cancer risk. Although the added risk is small -- around one cancer per 1,000 scans -- it still stokes concern with more than 2 million CT heart scans done every year in the U.S.
In the new work, published in the Annals of Internal Medicine, researchers looked at the performance of low-radiation CT scans, technically known as prospectively gated CT.
Such scans cut the radiation dose to just less than 3 millisieverts, or around the yearly background radiation from natural sources. By comparison, people get about 12 millisieverts from a standard CT heart scan, the researchers say, and 7 to 9 from the catheter test.
The report summarizes 16 earlier studies that compared low-radiation CT scans with the catheter procedure. Most of the studies had been done outside of the U.S., and they included only 960 patients in total.
Pooling the results from each study, the researchers found low-radiation CT scans rule out heart problems just as effectively as the gold standard test.
The scans did result in 11 percent more false positives, however. But von Ballmoos said that was less important because those cases would just go on to have a catheter-based test.
The researchers note there was little information on the harms done by the tests, and von Ballmoos said they weren`t arguing for using heart scans in patients without symptoms.
"It`s not a test for the general population who don`t have chest pains," von Ballmoos told Reuters Health. "It is a diagnostic test, not a screening test."
Dr. Andrew J. Einstein, a cardiologist at Columbia University in New York, called the new findings "encouraging."
But Einstein, who was not part of the study, said not all patients are candidates for the test, because they need to have a slow heart rate, and can`t have lots of irregular heartbeats.
Einstein estimates about 85 percent of patients who are seen for suspected heart disease are good candidates for the test, which is available in many hospitals across the country.
"I think it is certainly reasonable to ask if they are being sent to an imaging facility that has the capability of using this" technique, he told Reuters Health.
"It is always a balance of the benefits and risks of the testing options available," he added. "In general, if there is a non-invasive test that works as well as an invasive one, that`s going to be a better choice for a patient than an invasive test."
First Published: Tuesday, March 15, 2011, 00:00
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