A new, 'next-generation' blood test that speeds up the time it takes to help diagnose heart attacks was recently cleared by the U.S. Food and Drug Administration (FDA). Though the test has been used in other countries for seven years, it only became cleared for use in the U.S. on January 18, 2017.
The test measures a patient’s blood level of cardiac troponin, a protein that is a specific marker of cardiac cell death. Troponin is released into the bloodstream when cardiac cells are damaged by an interruption of blood flow to a part of the heart, which is what happens during a heart attack (acute myocardial infarction).
Confirming or ruling out a heart attack is critical because about five million people seek care at emergency rooms complaining of chest pain every year, but only about 5 to 20 percent are actually having a heart attack. Other causes of chest pain can include digestive system problems, anxiety and stress, or other heart conditions, but physicians say chest pain should never be ignored.
A blood test to check troponin levels, along with an electrocardiogram (ECG) and assessment of signs and symptoms such as chest pain, are standard care in the ER. Conventional troponin tests are typically performed when a person with a suspected heart attack first comes into the emergency room, followed by a series of troponin tests performed over several hours. The test needs to be repeated because it could take an average of three to four hours for troponin levels to increase in patients having a heart attack. Significantly elevated troponin levels and, in particular, a rise in the levels over several hours means it is likely that the person has had a heart attack or some other form of damage to the heart.
The new test, also known as a high-sensitivity troponin test, detects the same protein that the standard test does but at much lower levels. Because this version of the test is more sensitive, it can detect increases in blood troponin sooner after a person experiences a heart attack and chest pain compared to the standard test. New research published in the January 2017 issue of Clinical Chemistry suggests that high-sensitivity tests may allow healthcare practitioners to rule out acute myocardial infarction earlier, using a single blood test obtained when a patient arrives in the emergency department. If so, there would be no need for serial blood testing, as is currently required and recommended for the standard test.
Interviewed in TCTMD, an interventional cardiology publication, about the new troponin test, James Januzzi, Jr, MD, a professor of medicine at Harvard Medical School said "…chest discomfort is one of the most common diagnoses we see in the emergency department setting, and having a more sensitive test to identify or exclude acute myocardial infarction is a big step forward."