Heart Health

Updated 26 April 2017

Blood test may gauge death risk after surgery

A study found that testing for a protein found in heart muscle can help identify those post-op patients most at risk of heart disease.

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Traditionally blood tests are used to help doctors check for certain diseases and conditions and help check the function of our organs. But now, according to a recent study, a highly sensitive blood test can identify patients with a raised risk of death in the month after surgery.  

On average, 1% of patients die within 30 days after noncardiac surgery – most from a heart attack, said researcher Dr P.J. Devereaux, a professor at McMaster University in Ontario, Canada.

Testing for a protein called troponin that's found in heart muscle can help identify those post-op patients most at risk, Devereaux and an international team of researchers reported.

However, the study, which was published in the Journal of the American Medical Association, could not prove a direct cause-and-effect relationship between troponin levels and death risk.

Affordable test

Surgery is a major stress to the body's organs. Troponin is released into the blood when the heart muscle has been damaged, Devereaux explained.

"Most of the heart injuries happen in the first day-and-a-half after surgery, when most patients are getting narcotics that can mask typical heart symptoms," said Devereaux, who specialises in health research methods, evidence and impact.

The US Food and Drug Administration recently approved a high-sensitivity troponin test. Devereaux's team found it accurately pinpointed at-risk patients – even those with no obvious symptoms of heart damage.

At its highest levels in the first three days after surgery, troponin can indicate a nearly 30% increased risk of heart attack within a month, the researchers found.

Measuring troponin after an operation should be part of standard care, Devereaux said, adding that the test is relatively inexpensive.

A simple blood test might provide a new way to detect signs of concussion – especially if no symptoms are present immediately –  up a week after patients suffered a head injury, researchers previously reported.

A recent study suggests that a highly sensitive blood test may aid doctors in ruling out heart attack for nearly two-thirds of people who seek emergency room treatment for chest pain. The blood test may rule out heart attack fairly quickly, which could reduce unnecessary hospital visits and accompanying costs.

Researchers are also claiming that an experimental blood test has shown promise as a method to diagnose autism in children. The test proved to be nearly 98% accurate in children aged three to 10 years.

Heart injury may otherwise go 'unnoticed'

"One of the biggest risks with any kind of surgery is a heart attack during or immediately after the operation," said Dr Byron Lee, a professor of medicine and director of electrophysiology laboratories and clinics at the University of California, San Francisco.

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This new test picks up minor injury to the heart that could go unnoticed, he said.

However, "in order for this to be truly groundbreaking, we will need to find ways to protect the patients who test positive," Lee said.

Dr Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, agreed that the test by itself isn't enough to keep patients alive.

"While this biomarker identifies patients at higher risk for dying, further studies are needed to determine if this information can be used in a way that will modify the risk and improve outcomes in postoperative patients," Fonarow said.

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