What are cardiac biomarkers?
Cardiac biomarkers are substances that are released into the blood when the heart is damaged or stressed. Measurement of these biomarkers is used to help diagnose, risk stratify, monitor and manage people with suspected acute coronary syndrome (ACS) and cardiac ischemia. The symptoms of ACS and cardiac ischemia can vary greatly but frequently include chest pain, pressure, nausea, and/or shortness of breath. These symptoms are associated with heart attacks and angina, but they may also be seen with non-heart-related conditions. Increases in one or more cardiac biomarkers can identify people with ACS or cardiac ischemia, allowing rapid and accurate diagnosis and appropriate treatment of their condition.
ACS is caused by rupture of a plaque that results from atherosclerosis. Plaque rupture causes blood clot (thrombus) formation in coronary arteries, which results in a sudden decrease in the amount of blood and oxygen reaching the heart. Cardiac ischemia is caused when the supply of blood reaching heart tissue is not enough to meet the heart’s needs. The root causes of both ACS and cardiac ischemia are usually atherosclerosis and buildup of plaque, resulting in severe narrowing of the coronary arteries or a sudden blockage of blood flow through these arteries. Angina is caused by a decrease in the supply of blood to the heart. When blood flow to the heart is blocked or significantly reduced for a longer period of time (usually for more than 30-60 minutes), it can cause heart cells to die and is called an acute myocardial infarction (AMI or heart attack). This leads to death of the affected portion of heart muscle with permanent damage and scarring of the heart and sometimes can cause sudden death to the person.
Cardiac biomarker tests are ordered to help detect the presence of ACS and cardiac ischemia and to evaluate their severity as soon as possible so that appropriate therapy can be initiated. It is important to distinguish heart attacks from angina, heart failure, or other conditions that may have similar signs and symptoms because the treatments and monitoring requirements are different. For heart attacks, prompt medical intervention is crucial to minimize heart damage and future complications. Cardiac biomarker tests must be available to the doctor 24 hours a day, 7 days a week with a rapid turn-around-time. Some of the tests may be performed at the point of care (POC) – in the Emergency Room or at the person’s bedside. Serial testing of one or more cardiac biomarkers is necessary to ensure that a rise in blood levels is not missed and to estimate the severity of a heart attack.
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 skeletal muscle injury, liver disease, or kidney disease. Many other potential cardiac biomarkers are being researched, but their clinical utility has yet to be established.
Current cardiac biomarker tests used to help diagnose, evaluate, and monitor individuals suspected of having acute coronary syndrome (ACS) include:
Other biomarker tests that may be used:
- 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
Phased out biomarkers—the tests below are not specific for damage to the heart and are no longer recommended for evaluating people with suspected ACS:
More general tests frequently ordered along with cardiac biomarkers include:
These tests allow doctors 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.