Cardiac Biomarker Tests
Only a few cardiac biomarker tests are routinely used by physicians. The current biomarker test of choice for detecting heart damage is troponin. Other cardiac biomarkers are less specific for the heart and may be elevated in other situations such as skeletal muscle injury.
Current cardiac biomarker tests that may be used to help diagnose, evaluate, and monitor individuals suspected of having acute coronary syndrome (ACS) include:
- Troponin (I or T)—this is the most commonly ordered and most specific of the cardiac markers. It is elevated (positive) within a few hours of heart damage and remains elevated for up to two weeks. Rising levels in a series of troponin tests performed over several hours can help diagnose a heart attack.
- High-sensitivity troponin—this test detects the same protein that the standard test does, just at much lower levels. Because this version of the test is more sensitive, it becomes positive sooner and may help detect ACS earlier than the standard test. The hs-troponin test may also be positive in people with stable angina and even in people with no symptoms. When it is elevated in these individuals, it indicates an increased risk of future heart events such as heart attacks. Currently, this test is not approved in the U.S., but research is ongoing and it may become available in the near future. It is already routinely used as a cardiac biomarker in clinical practice in Europe, Canada, and other countries as well.
- Creatine kinase (CK) and CK-MB—in the U.S., CK has been largely replaced by troponin. It may sometimes be used to help detect a second heart attack that occurs shortly after the first. CK-MB is one particular form of the enzyme creatine kinase that is found mostly in heart muscle; it rises when there is damage to the heart muscle cells and may be used in follow up to an elevated CK and/or when the troponin test is not available.
- Myoglobin—this test may be used along with troponin to detect a heart attack early, but in the U.S., it is used less frequently.
Other biomarker tests that may be used include:
- hs-CRP—this test may be used to help determine risk of future heart attacks in people who have already suffered one in the past.
- BNP (or NT-proBNP)—although usually used to recognize heart failure, an increased level in people with ACS indicates an increased risk of recurrent events.
On the horizon: several biomarkers are being investigated for their potential use in helping to evaluate people for ACS. These are currently only used in research settings and are not available in clinical practice.
General lab tests are frequently ordered along with cardiac biomarkers to evaluate a person's general health status and the current status of the individual's kidneys, liver, electrolyte and acid/base balance, blood sugar, and blood proteins. They may include:
- Blood gases
- Comprehensive metabolic panel (CMP) or basic metabolic panel (BMP)
- Complete blood count (CBC)
These tests allow health practitioners to look at the size, shape, and function of the heart as it is beating. They can be used to detect changes to the rhythm of the heart as well as to detect and evaluate damaged tissues and blocked arteries.
- EKG (ECG, electrocardiogram)
- Nuclear scan
- Coronary angiography (or arteriography)
- Echocardiogram (Cardiac echo, transthoracic echocardiography (TTE))
- Stress testing
- Chest X-ray
For more about these, visit the Non-Invasive Tests and Procedures article on the American Heart Association web site.