Preparing the United States for High-Sensitivity Cardiac Troponin Assays
The following are 10 points to remember about this state-of-the-art paper:
1. The use of the 99th percentile upper reference limit (URL) increases the ability of cardiac troponin (cTn) assays to detect both acute myocardial infarction (AMI) and structural cardiac morbidities.
2. The authors advocate the use of the term ‘high-sensitivity cardiac troponin assays’ (hs-cTn) for cTn assays that measure cTn values in at least 50% of a reference population. Ideally, assays should have a coefficient of variation of <10% at the 99th percentile value.
3. Routine use of hs-cTn assays in the United States is inevitable in the future. These assays hold the promise of improving the sensitivity of AMI diagnoses, shortening the duration of AMI evaluation, and improving the risk stratification of other noncardiac diagnoses.
4. The optimal delta criteria for distinguishing between acute and chronic cardiac injury remain unclear, and are likely to be assay-specific.
5. Distinguishing between type 1 and type 2 AMI is challenging, and more type 2 AMIs will be detected with hs-Tn assays.
6. Regardless of reference values, solitary elevations of hs-cTn values (>99th percentile) will be inadequate for clinical decision making. The exception may be very elevated values, which are most often caused by MI or myocarditis, once possible analytical confounding factors are eliminated. In other circumstances, serial changes in hs-cTn values will be required to determine whether acute myocardial injury is present.
7. Factors affecting the analytical precision of troponin assays (including how we collect samples) will become more important with the use of hs-cTn assays.
8. Elevated hs-cTn, regardless of the cause, has important prognostic implications and deserves additional evaluation; many cases of chronic elevations can be evaluated in an outpatient setting.
9. Hs-cTn can be used to risk-stratify patients with non–acute coronary syndrome cardiovascular comorbidities.
10. Clinicians need to learn how to use the 99th% URL and the concept of changing values so that when the day comes that hs-cTn assays are available, they will have experience with the important basic concepts.
Keywords: Prognosis, Myocardial Infarction, Acute Coronary Syndrome, Biological Markers, Outpatients, Decision Making, Cardiology, Comorbidity, Myocarditis, United States, Troponin
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