What are cardiac markers?

Updated: Jul 30, 2021
  • Author: Kamal (Komo) Gursahani, MD, MBA; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Cardiac markers are used for the diagnosis and risk stratification of patients with chest pain and suspected acute coronary syndrome (ACS) and for management and prognosis in patients with acute heart failure, pulmonary embolism, and other disease states. Cardiac markers can be classified into those that signify myocardial necrosis (creatine kinase-MB [CK-MB] fraction, myoglobin and cardiac troponins), those that indicate myocardial ischemia (ischemia modified albumin), those that suggest myocardial stress (natriuretic peptides), and those markers of inflammation and prognosis (C-reactive protein [CRP], soluble CD40 ligand [sCD40L], and homocysteine). [1]

The cardiac troponins, in particular, have become the cardiac markers of choice for patients with ACS, eclipsing CK-MB and myoglobin in terms of clinical value. Indeed, cardiac troponin is central to the definition of acute myocardial infarction (MI) in the consensus guidelines from the European Society of Cardiology (ESC) and the American College of Cardiology (ACC): These guidelines recommend that cardiac biomarkers should be measured at presentation in patients with suspected MI, and that the only biomarker that is recommended to be used for the diagnosis of acute MI at this time is cardiac troponin due to its superior sensitivity and accuracy. [2, 3, 4, 5, 6]

For example, patients with elevated troponin levels but negative CK-MB values who were formerly diagnosed with unstable angina or minor myocardial injury are now reclassified as non–ST-segment elevation MI (NSTEMI), even in the absence of diagnostic electrocardiographic (ECG) changes.

Similarly, only one elevated troponin level above the established cutoff is required to establish the diagnosis of acute MI, according to the ACC guidelines for NSTEMI. [3, 7, 8]

These changes were instituted following the introduction of increasingly sensitive and precise troponin assays. Up to 80% of patients with acute MI will have an elevated troponin level within 2-3 hours of emergency department (ED) arrival, versus 6-9 hours or more with CK-MB and other cardiac markers. [6]

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