Highly Sensitive Troponin Assays and the Cardiology Community: A Love/Hate Relationship?
The following are 10 key points about the highly sensitive troponin assays and the cardiology community:
1. New highly sensitive troponin assays offer new opportunities to improve cardiovascular health, but they also present challenges in the areas in which troponin testing is most commonly used today.
2. Highly sensitive assays for cardiac troponin (cTn) T and cTn I are more sensitive and more precise tools for identifying cardiac injury, with the ability to detect cTn concentrations 10-fold lower than the current prior assays, with high precision at the myocardial infarction (MI) detection limit.
3. In multiple large population-based studies, higher cTn concentrations have been strongly associated with an increased risk for all-cause and cardiovascular disease mortality, as well as heart failure. In contrast, the association for coronary heart disease events is much weaker.
4. Studies have demonstrated that the addition of cTn augments traditional risk-prediction models, such as the Framingham risk score, with improved discrimination and risk classification, performed at least as well as N-terminal pro-B-type natriuretic peptide, and outperformed high-sensitivity C-reactive protein.
5. Prior to widespread use, it will be necessary to identify lifestyle factors or drug treatments that can modify the risk associated with low-level increases in troponins; ideally, such treatments would also reduce the troponin concentration so that serial testing could be used to monitor treatment effectiveness.
6. Although structural heart disease and chronic kidney disease appear to explain some of the variation in troponin concentrations, troponins may function as nonspecific markers of “end-organ damage,” reflecting the final common pathway of multiple different pathways to chronic cardiac injury.
7. Although a troponin measurement is inexpensive, the impact and cost of downstream testing, particularly cardiovascular imaging, will need to be assessed prior to implementation of a screening strategy.
8. In the acute setting, more sensitive troponin assays improved discrimination of MI events, particularly in the early hours after symptom onset, and may allow more patients to be sent home sooner.
9. However, the majority of individuals presenting to an emergency department with chest symptoms will have measurable troponin concentrations. Appropriate interpretation of troponin results will require global assessment of the clinical probability of myocardial ischemia, rather than simply interpreting troponin results as positive or negative.
10. The adoption of highly sensitive assays for MI detection will require development of algorithms for interpreting detectable troponin values that are below the MI threshold, together with recommendations for additional testing and referral for patients with an increased cTn concentration and a low clinical suspicion for acute coronary syndrome.
A triad of knowledgeable experts in the field provide a valuable perspective concerning the use of high-sensitivity cTn assays. These assays are already in use in most of the world and eventually will be approved for use in the United States; thus, learning about them sooner rather than later is suggested.
Keywords: Myocardial Infarction, Acute Coronary Syndrome, Myocardial Ischemia, Biological Markers, Heart Failure, Coronary Disease, Renal Insufficiency, Chronic, United States, Treatment Outcome, Troponin, Natriuretic Peptide, Brain
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