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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.
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 by causing irregular heart contractions (arrhythmia). Unstable angina and AMI are together called acute coronary syndrome since they are both due to a very acute decrease in blood flow to the heart.
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.
|Marker||what it is||Tissue source||Reason for Increase||Time to Increase||Time Back to Normal||When/How Used|
|Cardiac Troponin||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
Currently not approved in U.S. but may be soon; it is routinely used in Canada, Europe
|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)|
|CK||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|
|CK-MB||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|
|Myoglobin||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|
|bioMarker||what it is||Reason for Increase||When/How Used|
|hs-CRP||Protein||Inflammation||May help determine risk of future cardiac events in those patients who have had a heart attack|
|BNP and NT-proBNP||Heart hormone||Heart failure; increased risk of another heart attack||Usually used to recognize heart failure, but an increased level in people with ACS indicates an increased risk of recurrent events|
Sources Used in Current Review
Coven, D. and Kalyanasundaram, A. (Updated 2015 April 2). Acute Coronary Syndrome. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/1910735-overview through http://emedicine.medscape.com. Accessed April 2015
Schreiber, D. and Miller, S. (Updated 2014 December 18). Cardiac Markers. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/811905-overview through http://emedicine.medscape.com. Accessed April 2015
(© 1995–2015). ST2, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/61723 through http://www.mayomedicallaboratories.com. Accessed April 2015
(© 1995–2015). Lipoprotein Associated Phospholipase A2 (PLAC). Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/57353 through http://www.mayomedicallaboratories.com. Accessed April 2015
Henry-Okafor, Q. et. al. (2012 April 20). Soluble ST2 as a Diagnostic and Prognostic Marker for Acute Heart Failure Syndromes. Open Biomark J. 2012 Apr 20; 2012(5): 1–8. [On-line information]. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3578210/ through http://www.ncbi.nlm.nih.gov. Accessed April 2015
McLean, A. and Huang, S. (2012). Cardiac biomarkers in the intensive care unit. Annals of Intensive Care 2012, 2:8 [On-line information]. Available online at http://www.annalsofintensivecare.com/content/pdf/2110-5820-2-8.pdf through http://www.annalsofintensivecare.com. Accessed April 2015
Delgado, J. et. al. (2014 November).Cardiovascular Disease (Non-traditional Risk Markers) - Risk Markers - CVD (Non-traditional). ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/CVDRiskMarkerNontrad.html?client_ID=LTD through http://www.arupconsult.com. Accessed April 2015
Stone, N. J. et. al. (2013 ). 2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;00:000–000 [On-line information]. Available online at http://circ.ahajournals.org/content/early/2013/11/11/01.cir.0000437738.63853.7a through http://circ.ahajournals.org. Accessed April 2015
Apple F, et. al. Future Biomarkers for Detection of Ischemia and Risk Stratification in Acute Coronary Syndrome. Clinical Chemistry May 2005 vol. 51 no. 5 810-824. Available online at http://www.clinchem.org/content/51/5/810.long through http://www.clinchem.org. Accessed April 2015.
Sherwood M, Newby L. High‐Sensitivity Troponin Assays: Evidence, Indications, and Reasonable Use. J Am Heart Assoc. 2014; 3: e000403 originally published January 27, 2014 doi: 10.1161/JAHA.113.000403. Available online at http://jaha.ahajournals.org/content/3/1/e000403.full through http://jaha.ahajournals.org. Accessed June 2015.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Morrow, D. et. al. (2004 April 8). Clinical: Acute Coronary Syndromes – Chapter 1. NACB Laboratory Medicine Practice Guidelines [On-line Draft Guidelines]. Available online at http://www.nacb.org/lmpg/biomark/card_biomarkers_chp1.doc through http://www.nacb.org.
Tang, W., et. al. (2004 February 27, Second Draft). NACB: Recommendations for the use of Cardiac Biomarkers in Heart Failure. [On-line Draft Guidelines]. Available online at http://www.nacb.org/lmpg/biomark/card_biomarkers_chp2.doc through http://www.nacb.org.
Canto, J. (2002 July 1) Cardiac Biomarkers in Acute Coronary Syndrome, An Update in 2002. Univ of Alabama School of Medicine Division of Continuing Medical Education and Alabama Quality Assurance Foundation [On-line CME]. Available online at http://www.cme.uab.edu/onlineCourses/CardiacBiomarkers/ID0073.htm through http://www.cme.uab.edu.
Titus, Karen. (March 2004) The Latest on IMA Levels, High and Low. CAP Today. Available online at http://www.cap.org/apps/docs/cap_today/feature_stories/0304IMA.html through http://www.cap.org.
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 1035, 319, 321, 668, 950, 670.
Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC. Pp 306-315.
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 261-268.
Christenson, R., Editor (© 2007). Biomarkers of Acute Coronary Syndrome and Heart Failure. National Academy of Clinical Biochemistry, Laboratory Medicine Practice Guidelines [On-line information]. Available online at http://www.aacc.org/AACC/members/nacb/LMPG/OnlineGuide/PublishedGuidelines/ACSHeart/ through http://www.aacc.org. Accessed on 2/24/08.
Weinrauch, L. (2007 March 30, Updated). Heart Attack. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000195.htm . Accessed on 2/17/08.
(2007 May). What is a Heart Attack. National Heart Lung and Blood Institute. Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/HeartAttack/HeartAttack_WhatIs.html through http://www.nhlbi.nih.gov. Accessed on 2/17/08.
Schreiber, D. and Miller, S. (2006 June 26, Updated). Use of Cardiac Markers in the Emergency Department. emedicine. Available online at http://www.emedicine.com/emerg/TOPIC932.HTM through http://www.emedicine.com. Accessed on 2/24/08.
(2007 April). April 2007 Clinical Laboratory News: New NACB Guidelines Emphasize Cardiac Troponin for ACS. Clinical Laboratory News April 2007: v33 (4). Available online at http://www.aacc.org/AACC/publications/cln/2007/april/cover1_0407.htm through http://www.aacc.org. Accessed on 2/17/08.
(July 2, 2008). Journal of American Medical Association, Patient page: Acute Coronary Syndrome. (JAMA, Vol 300, No. 1). PDF available for download at http://jama.ama-assn.org/cgi/reprint/300/1/132.pdf through http://jama.ama-assn.org. Accessed July 2008.
American Heart Association: What is Acute Coronary Syndrome? Available online at http://www.americanheart.org/presenter.jhtml?identifier=3010002 through http://www.americanheart.org. Accessed July 2008.
Zieve, D. (Updated 2010 March 15). Troponin Test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/007452.htm. Accessed November 2011.
Dugdale, D. (Updated 2011 February 21). Myoglobin – serum. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003663.htm. Accessed November 2011.
Grenache, D. et. al. (Updated 2011 January). Ischemic Heart Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/IHD.html#tabs=0 through http://www.arupconsult.com. Accessed November 2011.
Mayo Clinic staff (Updated 2010 May 19). Myocardial ischemia. Mayo Clinic [On-line information]. Available online at http://www.mayoclinic.com/health/myocardial-ischemia/DS01179/METHOD=print through http://www.mayoclinic.com. Accessed November 2011.
Zafari, A.M. (Updated 2011 October 11). Myocardial Infarction. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/155919-overview through http://emedicine.medscape.com. Accessed November 2011.
(April 28, 2004) National Academy of Clinical Biochemistry (NACB): Laboratory Medicine Practice Guidelines – Biomarkers of Acute Coronary Syndromes and Heart Failure. Accessed November 2011.
Robert H. Christenson, Ph.D., DABCC, FACB. Professor of Pathology, Professor of Medical and Research Technology. Director, Rapid Response Laboratories, University of Maryland School of Medicine, Baltimore, Maryland.