Cardiac markers
Encyclopedia
Biomarker (medicine)
In medicine, a biomarker is a term often used to refer to a protein measured in blood whose concentration reflects the severity or presence of some disease state...
measured to evaluate heart function. They are often discussed in the context of myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
, but other conditions can lead to an elevation in cardiac marker level.
Most of the early markers identified were enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s, and as a result, the term "cardiac enzymes" is sometimes used. However, not all of the markers currently used are enzymes. For example, in formal usage, troponin would not be listed as a cardiac enzyme.
Types
Types include:| Test | Sensitivity and specificity Sensitivity and specificity Sensitivity and specificity are statistical measures of the performance of a binary classification test, also known in statistics as classification function. Sensitivity measures the proportion of actual positives which are correctly identified as such Sensitivity and specificity are statistical... |
Approximate peak | Description |
|---|---|---|---|
| Troponin test Troponin test The troponin test can be used as a test of several different heart disorders, including myocardial infarction.-Cardiac conditions:Certain subtypes of troponin are very sensitive and specific indicators of damage to the heart muscle... |
The most sensitive and specific test for myocardial damage. Because it has increased specificity compared with CK-MB, troponin is a superior marker for myocardial injury. | 12 hours | Troponin is released during MI from the cytosolic pool of the myocytes. Its subsequent release is prolonged with degradation of actin and myosin filaments. Differential diagnosis of troponin elevation includes acute infarction, severe pulmonary embolism causing acute right heart overload, heart failure, myocarditis. Troponins can also calculate infarct size but the peak must be measured in the 3rd day. released in 2–4 hours and persists for up to 7 days. |
| Creatine Kinase (CK-MB) test | It is relatively specific when skeletal muscle damage is not present. | 10–24 hours | CK-MB resides in the cytosol and facilitates high energy phosphates into and out of mitochondria. It is distributed in a large number of tissues even in the skeletal muscle. Since it has a short duration, it cannot be used for late diagnosis of acute MI but can be used to suggest infarct extension if levels rise again. This is usually back to normal within 2–3 days. |
| Lactate dehydrogenase Lactate dehydrogenase Lactate dehydrogenase is an enzyme present in a wide variety of organisms, including plants and animals.Lactate dehydrogenases exist in four distinct enzyme classes. Two of them are cytochrome c-dependent enzymes, each acting on either D-lactate or L-lactate... (LDH) |
LDH is not as specific as troponin. | 72 hours | Lactate dehydrogenase catalyses the conversion of pyruvate to lactate Lactate Lactate may refer to:*The act of lactation*The conjugate base of lactic acid... . LDH-1 isozyme is normally found in the heart muscle and LDH-2 is found predominately in blood serum. A high LDH-1 level to LDH-2 suggest MI. LDH levels are also high in tissue breakdown or hemolysis. It can mean cancer Cancer Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the... , meningitis Meningitis Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs... , encephalitis Encephalitis Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue... , or HIV HIV Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive... . this usually back to normal 10–14 days. |
| Aspartate transaminase Aspartate transaminase Aspartate transaminase , also called aspartate aminotransferase or serum glutamic oxaloacetic transaminase , is a pyridoxal phosphate -dependent transaminase enzyme . AST catalyzes the reversible transfer of an α-amino group between aspartate and glutamate and, as such, is an important enzyme in... (AST) |
This was the first used. It is not specific for heart damage, and it is also one of the liver function tests Liver function tests Liver function tests , are groups of clinical biochemistry laboratory blood assays designed to give information about the state of a patient's liver. The parameters measured include PT/INR, aPTT, albumin, billirubin and others... . |
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| Myoglobin Myoglobin Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates in general and in almost all mammals. It is related to hemoglobin, which is the iron- and oxygen-binding protein in blood, specifically in the red blood cells. The only time myoglobin is found in the... (Mb) |
low specificity for myocardial infarction Myocardial infarction Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die... |
2 hours | Myoglobin is used less than the other markers. Myoglobin is the primary oxygen-carrying pigment of muscle tissue. It is high when muscle tissue is damaged but it lacks specificity. It has the advantage of responding very rapidly, rising and falling earlier than CK-MB or troponin. It also has been used in assessing reperfusion after thrombolysis Thrombolysis Thrombolysis is the breakdown of blood clots by pharmacological means. It is colloquially referred to as clot busting for this reason... . |
| Ischemia-modified albumin (IMA) | low specificity | IMA can be detected via the albumin cobalt binding (ACB) test, a limited available FDA approved assay. Myocardial ischemia alters the N-terminus of albumin reducing the ability of cobalt to bind to albumin. IMA measures ischemia in the blood vessels and thus returns results in minutes rather than traditional markers of necrosis that take hours. ACB test has low specificity therefore generating high number of false positives and must be used in conjunction with typical acute approaches such as ECG and physical exam. Additional studies are required. | |
| Pro-brain natriuretic peptide | This is increased in patients with heart failure. It has been approved as a marker for acute congestive heart failure. Pt with < 80 have a much higher rate of symptom free survival within a year. Generally, pt with CHF will have > 100. | ||
| Glycogen phosphorylase isoenzyme BB Glycogen phosphorylase isoenzyme BB Glycogen phosphorylase isoenzyme BB is an isoenzyme of glycogen phosphorylase. This isoform of the enzyme exists in cardiac and brain tissue.... |
high sensitivity and specificity early after chest pain | 7 hours | Glycogen phosphorylase isoenzyme BB (abbreviation: GPBB) is an isoenzyme of glycogen phosphorylase. Glycogen phosphorylase exists in 3 isoforms. One of these Isoforms is GP-BB. This isoform exists in heart and brain tissue. Because of the blood-brain barrier GP-BB can be seen as heart muscle specific. During the process of ischemia, GP-BB is converted into a soluble form and is released into the blood. This isoform of the enzyme exists in cardiac (heart) and brain tissue. GP-BB is one of the "new cardiac markers" which are discussed to improve early diagnosis in acute coronary syndrome. A rapid rise in blood levels can be seen in myocardial infarction and unstable angina. GP-BB elevated 1–3 hours after process of ischemia. |
Alcohol septal ablation
Alcohol septal ablation is a percutaneous, minimally-invasive treatment performed by an interventional cardiologist to relieve symptoms and improve functional status in severely symptomatic patients with hypertrophic cardiomyopathy who meet strict clinical, anatomic and physiologic selection...
has led to the identification of additional potential markers.
Limitations
Depending on the marker, it can take between 2 to 24 hours for the level to increase in the blood. Additionally, determining the levels of cardiac markers in the laboratory - like many other lab measurements - takes substantial time. Cardiac markers are therefore not useful in diagnosing a myocardial infarctionMyocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
in the acute phase. The clinical presentation and results from an ECG are more appropriate in the acute situation.
However, in 2010, research at the Baylor College of Medicine
Baylor College of Medicine
Baylor College of Medicine, located in the Texas Medical Center in Houston, Texas, USA, is a highly regarded medical school and leading center for biomedical research and clinical care...
revealed that, using diagnostic nanochips and a swab of the cheek, cardiac biomarker readings from saliva can, with the ECG readings, determine within minutes whether someone is likely to have had a heart attack.
See also
- Myocardial markers in myocardial infarction
- Reference ranges for blood tests#Cardiac tests