Blood Test Shows Promise for Gauging Heart Attack Risk After Chest Pain
More study is needed, but the screening method measures levels of a chemical signal tied to heart damage
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The researchers then examined how many of these patients went on to suffer a heart attack within 30 days. During that time, only 39 of the patients included in the study had a heart attack, the researchers reported. Of these, 15 had no signs of damage due to reduced blood flow.
Overall, only one in every 594 patients who go to the emergency room for chest pain with no sign of heart damage and undetectable levels of troponin are at immediate risk for heart attack, the researchers calculated.
The study found a 99.8 percent probability that this subset of patients was not at risk for heart attack and a 100 percent probability that it wasn't at risk for death. This was true even after other risk factors for heart disease and how long the patients experienced symptoms were considered.
"Despite our observations before the study, we were still surprised by the strength of our findings," Bandstein noted.
Current guidelines recommend that high-sensitivity cardiac troponin T be tested at least three hours after chest pain begins. This usually means patients must be admitted to the hospital. The study's authors said their findings suggest that only one testing would be needed, which could prevent some unnecessary hospital admissions.
Two U.S. heart experts said the study gives support to the validity of the blood test.
"This study provides increasing evidence for the selective use of high-sensitivity cardiac troponin T to help evaluate patients with chest pain for evidence of possible heart attack," said Dr. Robert Glatter, an emergency medicine physician at Lenox Hill Hospital in New York City.
He did have two caveats, however: First, that more study is needed to validate the accuracy of the test. And second, that a small minority of patients did go on to suffer a heart attack in the month after a good test result.
"This is important to know because having a single normal or negative troponin [test result] initially does not completely remove all risk of suffering a heart attack after discharge from the emergency department," Glatter said.