How to Use High-Sensitivity Cardiac Troponins in Acute Cardiac Care

Perspective:

The following are 10 points to remember about this article:

1. A high-sensitivity (hs) cardiac troponin (cTn) T assay can measure cTn in the single digit range of nanograms per liter (= picograms per milliliter) and provide a more precise calculation of the 99th percentile of cTn concentration in reference subjects (the recommended upper reference limit [URL]).

2. The high precision of hs-cTn assays increases their ability to determine small differences in cTn over time.

3. The key differentiating feature of hs-cTn assays when compared with the former cTn assays is increased sensitivity, which is only apparent at values near the 99th percentile URL.

4. At least two measurements of hs-cTn to verify a kinetic pattern are required to comply with the universal definition of myocardial infarction (MI).

5. Use the 99th percentile concentration of the reference population as the cTn URL.

6. The diagnosis of acute myocardial necrosis requires a significant change with serial testing. At low cTn baseline concentrations (around the 99th percentile), the change in serial testing in order to be clinically significant requires to be marked, in case of markedly elevated baseline, a minimum change of >20% in follow-up testing is required.

7. Additional testing of other early markers of acute myocardial necrosis, such as myoglobin or creatine kinase-myocardial band, is no longer needed.

8. Blood sampling in patients with suspicion of acute MI should be performed on admission and 3 hours later. Measurement of hs-cTn should be repeated 6 hours after admission in patients of whom the 3-hour values are unchanged, but in whom the clinical suspicion of acute MI is still high.

9. cTn is a marker of myocardial necrosis and not a specific marker of acute MI. The latter may be only diagnosed with a rise and/or fall of cTn together with characteristic symptoms, and/or electrocardiogram changes indicative of ischemia and/or imaging evidence of acute myocardial ischemia. Consider also other causes of myocardial necrosis (e.g., acute heart failure or myocarditis) when an elevated hs-cTn test result is obtained.

10. Stable or inconsistently variable cTn values without significant dynamic changes are likely markers of chronic structural heart disease.

Clinical Topics: Acute Coronary Syndromes, Heart Failure and Cardiomyopathies, Acute Heart Failure

Keywords: Acute Coronary Syndrome, Myocardial Infarction, Phlebotomy, Creatine Kinase, MB Form, Troponin T, Transcription Factors, Myocarditis, Heart Diseases, Diterpenes, Troponin I, Heart Failure, Cardiovascular Diseases, Hospitalization


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