Cardiac biomarkers are substances that are released into the blood when the heart is damaged or stressed. Measurements of these biomarkers are used to help diagnose acute coronary syndrome (ACS) and cardiac ischemia, conditions associated with insufficient blood flow to the heart. Tests for cardiac biomarkers can also be used to help determine a person's risk of having these conditions or to help monitor and manage someone with suspected ACS and cardiac ischemia.
The root causes of both ACS and cardiac ischemia are usually the buildup of plaque in artery walls and hardening of the arteries (atherosclerosis). This can result in severe narrowing of the arteries leading to the heart or a sudden blockage of blood flow through these coronary arteries.
The symptoms of ACS and cardiac ischemia can vary greatly but frequently include chest pain, pressure, nausea, and/or shortness of breath. Though these symptoms are most often associated with heart attacks and angina, they may also be seen with non-heart-related conditions.
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. Cardiac biomarker tests are ordered to help detect the presence of ACS and cardiac ischemia and to evaluate their severity. Increases in one or more cardiac biomarkers in the blood can identify people with ACS or cardiac ischemia, allowing rapid and accurate diagnosis and appropriate treatment of their condition.
For ACS, prompt medical intervention is crucial to prevent death and to minimize heart damage and future complications. Cardiac biomarker tests must be available to a health practitioner 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 department or at a person's bedside. Usually, multiple cardiac biomarker tests are done over several hours 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 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:
Other biomarker tests that may be used include:
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:
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.
For more about these, visit the Non-Invasive Tests and Procedures article on the American Heart Association web site.
These tests are used to help diagnose, evaluate, and monitor people suspected of having Acute Coronary Syndrome (ACS).
|MARKER||WHAT IT IS||TISSUE SOURCE||REASON FOR INCREASE||TIME TO INCREASE||TIME BACK TO NORMAL||WHEN/HOW USED|
|Regulatory protein complex; two cardiac-specific isoforms: T and I||Heart||Injury to heart||3 to 4 hours||Remains elevated for 10 to 14 days||Diagnose heart attack, risk stratification, assist in deciding management, assess degree of damage|
High-sensitivity cardiac troponin
|Same as above, just measures the same protein at a much lower level||Heart||Injury to heart||Within 3 hours of onset of symptoms||Same as above||Same as above; may also be elevated in stable angina and people without symptoms and indicates risk of future cardiac events (e.g., heart attacks)|
|Enzyme; total of three different isoenzymes||Heart, brain, and skeletal muscle||Injury to skeletal muscle and/or heart cells||3 to 6 hours after injury, peaks in 18 to 24 hours||48 to 72 hours, unless due to continuing injury||Frequently performed in combination with CK-MB; sometimes to detect second heart attack occurring shortly after the first|
|Heart-related isoenzymes of CK||Heart primarily, but also in skeletal muscle||Injury to heart and/or muscle cells||3 to 6 hours after heart attack, peaks in 12 to 14 hours||48 to 72 hours, unless new or continuing damage||Less specific than troponin, may be ordered when troponin is not available|
|Oxygen-storing protein||Heart and other muscle cells||Injury to muscle and/or heart cells||2 to 3 hours after injury, peaks in 8 to 12 hours||Within one day after injury||Used less frequently; sometimes performed with troponin to provide early diagnosis|