It’s almost impossible to have an ER shift without encountering a chest pain patient!
The first thing that always comes to mind is to rule out STEMI; well, unless the patient is having chest pain, and you see a knife stabbed in his chest!
It’s a no brainer situation; investigations wise, you will start with an EKG, and a set of labs, including cardiac markers.
Acute coronary syndrome (ACS) with its subcategories, ST-elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), and unstable angina, is responsible for one third of total mortality in individuals more than 35 years of age.(1)
The role of cardiac markers in diagnosis and management of ACS and cardiovascular problems is vital. In the United States cardiac biomarkers testing occurs in nearly 30 million emergency department visits nationwide each year.(2)
What is a biomarker?
The National Institutes of Health defined a biomarker as “a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.” (3)
Biomarkers utilization in cardiovascular medicine is a wide domain; it’s used in screening, diagnosis, prognosis and monitoring. (4)
Numerous cardiac markers are available today and can be classified as:
- Biomarkers of myocardial injury, which is further divided into:
- Biomarkers of myocardial necrosis: CK-MB fraction, myoglobin, cardiac troponins
- Biomarkers of myocardial ischemia: Ischemia-modified albumin (IMA), heart-type fatty acid-binding protein (H-FABP)
- Biomarkers of hemodynamic stress: Natriuretic peptides (NPs): atrial natriuretic peptide (ANP), N-terminal proBNP (NT-proBNP), B-type natriuretic peptide (BNP)
- Inflammatory and prognostic markers: hs C-reactive protein (CRP), sCD40L, homocysteine. (4)
Cardiac Troponin and the B type cardiac natriuretic peptides are the two markers recommended by ACEP and AHA in diagnosis of ACS and heart failure respectively.(5)
The ACS biomarker of choice
ACS is subcategorized based on ECG and cardiac troponin. The fourth universal consensus definition of Myocardial Infarction (MI); by the European Society of Cardiology (ESC) and American College of Cardiology (ACC), takes Troponin as a detrimental parameter in case definition, because of its high sensitivity and specificity.(6)
ACEP and AHA guidelines recommend the use of Troponin as level A class 1 in diagnosis of ACS. (7) It was practiced before to consider multiple markers dealing with ACS, more precisely in NSTEMI ruling out recommendation. However, this practice is now outdated with the use of hs cT solely.(7-9)
What’s troponin and why do we like it?
It’s a protein that regulates the interaction between actin and myosin filaments, found in skeletal and cardiac myocytes. Cardiac troponin (cTn) has three subunits troponin T, troponin C and troponin I. Troponin T and I are highly specific and sensitive.(10) The half-life of troponin T and troponin I in the blood is about 2 hours and last in serum for 4 to 10 days10
For ACS, the sensitivity of troponin is about 95%, and the specificity is about 80%, higher than any other marker available.(12)
However, many causes can elevate serum troponin which includes pericarditis, myocarditis, heart failure and chest trauma; non-cardiac conditions are sepsis, renal disease, pulmonary embolism, COPD, strenuous exercise and hypertension.(14)
High-sensitivity cardiac troponin (hs-cTn T and I) can detect troponin at concentrations much lower than the old cTn tests, and has replaced it.7 For ACS, hs cT substituted and limited the roles of other markers; it’s proven to be safe, cost effective, and a valuable prognostic factor. (7-9, 14)
For all of the above and the heart score… In ACS, use Troponin and nothing more!
References and Further Reading
- Anumeha Singh; Abdulrahman S. Museedi; Shamai A. Grossman. Acute Coronary Syndrome. StatPearls[Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan.
- Alvin MD, Jaffe AS, Ziegelstein RC, Trost JC. Eliminating Creatine Kinase–Myocardial Band Testing in Suspected Acute Coronary Syndrome: A Value-Based Quality Improvement. JAMA Intern Med. 2017;177(10):1508-1512. doi:10.1001/jamainternmed.2017.3597.
- Biomarkers and surrogate endpoints: preferred definitions and conceptual framework. Biomarkers Definitions Working Group. Clin Pharmacol Ther. 2001 Mar; 69(3):89-95. doi.org/10.1067/mcp.2001.113989.
- Jacob R, Khan M. Cardiac Biomarkers: What Is and What Can Be. Indian J Cardiovasc Dis Women WINCARS. 2018 Dec; 3(4): 240–244. doi: 10.1055/s-0039-1679104.
- Richards AM. Future biomarkers in cardiology: My favourites. European Heart Journal Supplements, Volume 20, Issue suppl_ G, 1 August 2018, Pages G37-G44. doi.org/10.1093/eurheartj/suy023.
- Thygesen K, Alpert JS, Jaffe AS, et al., on behalf of the Joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/American Heart Association (AHA)/World Heart Federation (WHF) Task Force for the Universal Definition of Myocardial Infarction. Fourth Universal Definition of Myocardial Infarction (2018). J Am Coll Cardiol. 2018. Volume 72 DOI: 10.1016/j.jacc.2018.08.1038.
- Ezra A. Amsterdam, Nanette K Wenger, Ralph G. Brindis, Donald E. CaseyJr, Theodore G. Ganiats, David. HolmesJr, Allan S. Jaffe, Hani Jneid, Rosemary F. Kelly, Michael C. Kontos, Glenn N. Levine, Philip R. Liebson,Debabrata Mukherjee, Eric D. Peterson, Marc S. Sabatine, Richard W. Smalling, Susan J. Zieman. 2014 AHA/ACC Guideline for the Management of Patients With Non–ST-Elevation Acute Coronary Syndromes: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014; 130:e344–e426. 2014. doi.org/10.1161/CIR.0000000000000134.
- Edward W Carlton, Louise Cullen, Martin Than, James Gamble, Ahmed Khattab, Kim Greaves. A novel diagnostic protocol to identify patients suitable for discharge after a single high-sensitivity troponin. Heart. 2015 Jul 1; 101(13): 1041–1046. doi: 10.1136/heartjnl-2014-307288.
- Ron M. Walls, Robert S. Hockberger, Marianne Gausche-Hill, Katherine Bakes, Jill Marjorie Baren, Timothy B. Erickson, Andy S. Jagoda, Amy H. Kaji, Michael VanRooyen, Richard D. Zane. Rosen’s Emergency Medicine: Concepts and clinical practice. 9th edition. Elseivier; 2018.
- Ooi DS1, Isotalo PA, Veinot JP. Correlation of antemortem serum creatine kinase, creatine kinase-MB, troponin I, and troponin T with cardiac pathology. Clin Chem. 2000 Mar; 46(3):338-44.
- Harvey D. White, DSC. Pathobiology of Troponin Elevations: Do Elevations Occur With Myocardial Ischemia as Well as Necrosis?. Journal of the American College of Cardiology. Vol. 57, No. 24, ISSN 0735-1097/$36.00 Published by Elsevier Inc. doi:10.1016/j.jacc.2011.01.029.
- John E. Brush, Jr., Harlan M. Krumholz. A Brief Review of Troponin Testing for Clinicians. American College of Cardiology. 2017 Aug 7th. acc.org/latest-in-cardiology/articles/2017/08/07/07/46/a-brief-review-of-troponin-testing-for-clinicians.
- Asli Tanindi, Mustafa Cemri. Troponin elevation in conditions other than acute coronary syndromes. Vasc Health Risk Manag. 2011; 7: 597–603. PMID: 22102783. doi: 10.2147/VHRM.S24509.
- Donald Schreiber, Barry E Brenner. Cardiac Markers. emedicine.medscape.com/article/811905-overview [Accessed 2020 March 23rd].