A new and improved blood test for diagnosing heart attacks measures a heart protein that increases greatly in number when a person is having a heart attack. While existing tests are only accurate several hours after symptoms begin, the new high-sensitivity troponin (hsTn) assay is reliable much sooner.
From the University of Michigan, researchers describe the new hsTn assay as highly accurate, quick-working, and reliable. The faster the diagnosis, the faster the person gets the right treatment. Even for people not having a heart attack, detecting high levels of troponin can predict a risk of future heart disease. The new assay was approved by the FDA in January 2017.
Troponin is a cardiac regulatory protein that controls the calcium-mediated interaction between actin and myosin, two proteins responsible for producing force and cellular movement. Troponin is coded by specific genes and is likely unique to the myocardium, the heart’s muscle tissue.
“The high-sensitivity assay is able to measure tenfold lower concentrations of troponin, much smaller amounts than the current assay is able to,” explained University of Michigan’s Frederick Korley, MD, PhD. “It takes some time for the proteins to leave the heart and get into the bloodstream, so this new test can tell us a lot sooner whether you're having a heart attack or not.”
This is what makes the hsTn assay different from past and existing troponin tests. It can detect even the lowest quantities of troponin, determining a heart attack quickly after symptoms begin with accuracy, something existing tests have trouble doing.
Even worse, Korley says, using the past tests, “if you had a measurement before six hours and it's negative, you can't be confident it's truly negative. The first test may miss it.”
Even with the enhanced accuracy and reliability of the existing tests, scientists are still concerned about the risk over overdiagnosis and “undue hospitalization.”
“As clinicians, we are going to need to be savvy in interpreting the results and not necessarily think that if someone's troponin value is high the person is having a heart attack,” Korley said. “Institutions have to learn how well the test is operating in their hands, and how best to use it to derive the benefits.”
The present study was published in JAMA Cardiology.