Patient selection for high sensitivity cardiac troponin testing and diagnosis of myocardial infarction: prospective cohort studyBMJ 2017; 359 doi: https://doi.org/10.1136/bmj.j4788 (Published 07 November 2017) Cite this as: BMJ 2017;359:j4788
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We thank Dr Gupta for his comments on our study. Many clinicians incorrectly consider an elevated cardiac troponin concentration to be synonymous with myocardial infarction. Our analysis shows that widespread cardiac troponin testing without considering the pre-test probability of myocardial infarction has significant potential to limit the diagnostic utility of high-sensitivity cardiac troponin testing. If implemented without a considered approach to patient selection for testing, high-sensitivity cardiac troponin assays may increase diagnostic uncertainty and increase the need for further invasive and non-invasive cardiac investigations with cost implications for the healthcare system.
Although elevated cardiac troponin concentrations without acute coronary syndrome may be challenging to interpret, we acknowledge that they convey potentially important clinical information. In our analysis, nearly all of these patients were already recognised by their attending physician as being acutely unwell and were admitted to hospital. Cardiac troponin is a powerful prognostic marker, but currently no guidance exists on how to investigate patients with septicaemia or respiratory tract infarction who have elevated cardiac troponin concentrations, and as yet no evidence is available to suggest that cardiovascular treatments will improve outcomes in these conditions.
Competing interests: Speaker fees from Abbott Diagnostics
Bayes' theorem has already taught us: the positive predictive value of any test depends upon the pretest probability of the disease.
Therefore, the results of the study are not surprising. Testing of Troponin I is important not only to rule-in or to rule-out AMI, in the given context, but is equally important in evaluating prognosis (as one of the important parameters) in most critical illnesses like septicemia, severe injuries, cerebrovascular accidents, severe respiratory illnesses, etc.
Therefore readers of this paper should not limit the use of this important and sensitive biomarker to diagnose AMI only. Think about prognosis in any critical illness, even if it is non-cardiovascular.
Competing interests: No competing interests