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Blood test helps rule out heart attack in ER with 99-percent accuracy

A simple test that looks for a heart-related biomarker in the blood appears to be very effective at ruling out heart attacks in people who go to emergency rooms with chest pain, a major public health issue for patients.

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"Chest pain is a potentially life-threatening symptom, as well as being a very common one," lead researcher Dr. Nadia Bandstein, a professor of medicine at Karolinska Institute in Sweden, said in a statement. "Since there are no established ways to quickly rule out heart attack, many patients are admitted to the hospital unnecessarily, at a large cost to the patient and to society."

Her study of nearly 15,000 people found that the blood test plus the usual electrocardiogram (EKG) of the heartbeat were 99 percent accurate at showing which patients could safely be sent home rather than be admitted for observation and more diagnostics.

Of nearly 9,000 patients judged low risk by the blood test and with normal EKGs, only 15 went on to suffer a heart attack in the next month, and not a single one died.

"We believe that with this strategy, 20 to 25 percent of admissions to hospitals for chest pain may be avoided," said Bandstein.

She helped lead the study, published in the Journal of the American College of Cardiology and presented March 30 at the college's annual meeting in Washington.

Chest pain sends more than 15 million people to emergency rooms in the U.S. and Europe each year, and it usually turns out to be due to anxiety, indigestion or other less-serious things than a heart attack. Yet doctors don't want to miss one -- about 2 percent of patients having heart attacks are mistakenly sent home.

People may feel reassured by being admitted to a hospital so doctors can keep an eye on them, but that raises the risk of picking up an infection and having expensive care they'll have to pay a share of, plus unnecessary tests.

Researchers looked at people who went to the Karolinska University hospital with chest pains over two years. About 8,900 had low scores on a faster, more sensitive blood test for troponin, a substance that's a sign of heart damage. The test has been available in Europe, Asia and Canada for about three years, but it is not yet available in the U.S.

The patients were 47 years old on average and 4 percent had a previous heart attack. About 21 percent of them wound up being admitted.

Researchers later looked back to see how the blood test and EKG would have predicted how they fared over the next month.

They figured that in order to find one heart attack in patients like this, 594 would have to be admitted -- a huge waste of resources.

A test like this would be "enormously useful," and the study's results are "almost too good to be true," said Dr. Judd Hollander, an emergency medicine specialist at the University of Pennsylvania.

He believes the test should be available in the U.S. and that the amount of evidence that regulators are requiring to approve it is too high.

OtOther experts cautioned the test, while ruling out a heart attack, may not predict one.

"One should be very careful, however, not to conclude that the opposite is true -- if you have elevated high-sensitive troponin you are having a heart attack, as there is data to suggest that it is elevated after running a marathon," Dr. Sripal Bangalore, director of research in the Cardiac Catheterization Laboratory at NYU School of Medicine in New York City, told HealthDay.

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