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New Scanning Tool Could Prevent Unneeded Heart Attack Hospitalizations

Computerized technique reveals blocked arteries

MONDAY, Oct. 30, 2006 (HealthDay News) -- A new imaging technique may soon help doctors determine which people with chest pain can safely be sent home rather than hospitalized for a suspected heart attack.

The technique, coronary multidetector computed tomography (MDCT), successfully distinguished between people who had an acute coronary syndrome -- a heart attack or other severe heart problem -- and those who didn't. The small trial included 41 women and 62 men, with an average age of 54.

"The emphasis of the study was not to detect heart attack," said study author Dr. Udo Hoffman, an assistant professor of radiology at Harvard Medical School. "The emphasis was to rule it out."

A huge number of Americans -- possibly millions -- seek emergency care each year because of acute chest pain. In many cases, the doctor faces a quandary when the electrocardiogram and blood tests don't show signs of a heart attack.

"There is no good instrument right now that predicts whether those people will develop acute coronary syndrome," Hoffman said. "Only a small percentage will, as our study shows. But there is no incentive for the physicians to discharge a patient. They don't want to send home a patient who has an infarction [heart attack]."

MDCT scans could help physicians make the decision because they produce clear images of blood vessels, showing which are blocked by deposits of plaque and which are open to normal blood flow, he said.

The study included 103 people who came to Massachusetts General Hospital with acute chest pain. All had normal electrocardiograms and blood tests but were hospitalized because doctors suspected acute coronary syndrome. All agreed to undergo MDCT imaging before admission.

Only 14 of the 103 patients were diagnosed with acute coronary syndrome while in the hospital. In each case, MDCT scans showed significant plaque deposits. The scans did not show significant artery blockage in the patients who did not develop acute coronary syndrome.

"What this study shows is that when you do the MDCT picture of coronary artery disease, it distinguishes between patients who appear similar at baseline," Hoffman said.

The study results are published in the Oct. 31 issue of Circulation.

But MDCT testing, a 15-second, noninvasive scan, won't be widely available for some time at best, Hoffman said.

The trial results are "justification to move on to a randomized trial" to prove that the technology works, Hoffman said. An application for a controlled study that would include as many as 2,000 patients is being prepared for submission to the U.S. National Institutes of Health, he said, with the earliest starting time estimated to be "at the end of next year."

In addition, MDCT machines aren't found in every medical center, Hoffman said, although "availability is dramatically increasing. Almost every hospital, when they think about a new CT scanner, they think about major advances."

When the equipment is available, radiologists "will need to get experience with it and to trust in the findings of cardiac CT," he said. "There has not been big experience with it, and they will have to learn for themselves."

Despite all those caveats, MDCT scanning "has the potential to discharge about 30 percent of patients who now would be admitted," Hoffman said.

"Some hospitals already are using the technology in this manner, although it has never been tested very well," said Dr. Robert O. Bonow, chief of cardiovascular medicine at Northwestern University and a spokesman for the American Heart Association.

The new report is important because "it gives validity to the concept that it [MDCT] can have a useful role in determining which patients should be hospitalized," Bonow said.

"Still, one always wants to see confirmation from other centers," he said.

Another report in the same issue of the journal said that the speed in which artery-opening angioplasty is done is a key factor for the survival of heart-attack patients.

Previous studies had shown that patients who have angioplasty as a first treatment have a better chance of surviving than those getting clot-dissolving drugs, said the report by cardiologists at Harvard Medical School. Their new study of 192,509 patients listed in the National Registry of Myocardial Infarction found that delays in performing angioplasty over clot-dissolving therapy were associated with increased mortality.

Whatever therapy is done should be done quickly, the report said, since a 30-minute delay in restoring blood flow to the heart increased the death rate by 10 percent.

More information

The American Heart Association has more about heart attack symptoms.

SOURCES: Udo Hoffman, M.D., assistant professor, radiology, Harvard Medical School, Boston; Robert O. Bonow, M.D., chief of cardiovascular medicine, Northwestern University, Chicago, and spokesman, American Heart Association; Oct. 31, 2006, Circulation
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