A new blood test can help emergency room doctors determine more quickly whether patients with chest pain are having a heart attack, a US study confirms.
The test is a more sensitive version of the one that emergency physicians have been using. It detects a protein called troponin, which is released into the blood when the heart muscle is damaged, by a heart attack, for example.
But while the conventional troponin test takes three hours, the high-sensitivity version can give results in less than an hour.
Each year, millions of Americans land in an ER with chest pain or other potential symptoms of a heart attack, said Dr Rebecca Vigen, lead researcher on the study.
Most, however, have something else causing their symptoms.
A quicker answer
The hope with the new test is to more quickly rule out a heart attack in those patients, said Dr Vigen, a cardiologist at the University of Texas Southwestern Medical Center.
"If we can give patients and families an answer sooner, that would be a good thing," she added.
High-sensitivity troponin tests have been available in Europe and elsewhere for years. But the first such test in the United States, marketed by Roche Diagnostics, was just approved last year.
In the new study, Dr Vigen's team gauged how well that blood test is performing among patients at their Dallas hospital system. It used both the standard test and the high-sensitivity version to measure troponin levels in 536 patients who arrived at the emergency department with chest pain, shortness of breath or other possible heart attack symptoms.
Results in 30 minutes
The study was published online in the journal Circulation. Some of its co-authors have financial relationships with Roche.
Patients' troponin levels were measured when they arrived at the ER, and then again one and three hours later. The high-sensitivity test yielded results in about 30 minutes, Dr Vigen said.
Overall, the study found, that initial high-sensitivity test ruled out a heart attack in 30% of patients. The second, done at the one-hour mark, put another 25% in the clear. By the three-hour point, the high-sensitivity test had ruled out a heart attack in 84% of patients versus 80% with the conventional test.
The other patients had abnormal troponin results and received further evaluation. In the end, 2% were diagnosed with a heart attack, while others had heart-muscle damage from other causes. The high-sensitivity test did not miss any heart attacks, Dr Vigen said.
Substantially improved efficiency of care
Dr Christopher Granger is a cardiologist at Duke University in Durham, North Carolina. He also serves on the American College of Cardiology/American Heart Association guideline committee for heart attack care.
Granger said only a limited number of US hospitals now have the high-sensitivity troponin test.
"But I expect it will be rapidly adopted over the next few years," said Dr Granger, who was not involved in the study. Evidence from Europe already shows the benefits of high-sensitivity tests, he noted. "It has substantially improved the efficiency of care," Dr Granger said.
The test can help speed a heart attack diagnosis. But the biggest advantage, according to Dr Granger, is that it more quickly rules out a heart attack in the many patients who are not having one. "And that's important to patients and their families," he said.
One hope, Dr Granger noted, is that the quicker test will encourage people with possible heart attack symptoms to get help immediately. As it stands, people often dismiss symptoms because they don't want to go the ER.
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