LETTER TO THE EDITOR
Troponin and outcomes
Charles A. Henrikson, MD and
Nisha Chandra-Strobos, MD
Division of Cardiology, Johns Hopkins Medical Institutions, Carnegie 568, 600 North Wolfe Street, Baltimore, MD 21205
(Email: chenriks{at}jhmi.edu).
We read with interest the report of Kontos et al. (1), which showed that any detectable troponin I in the serum of patients admitted with chest pain was associated with worse outcomes. We recently reported the results of a similar study involving troponin T levels (2), and we found that among 428 patients admitted with ongoing chest pain, troponin T levels that were detectable but within the range reported as normal were markers of an increased risk of death/subsequent myocardial infarction/revascularization during the four-month follow-up.
We would like to comment on two aspects of the Kontos et al. (1) study: 1) the conclusion that most of thetests with detectable cardiac troponin I in the normal range "represent analytical false positive results due to the assays themselves" and 2) what to call detectable troponin values within the normal range. Troponin assays are exquisitely sensitive and, conceptually, a minor event, that cannot be detected clinically, can lead to a detectable level of troponin in the serum. Instead of thinking of detectable levels of troponin in patients with a negative subsequent workup as "false positive," we believe that the patientsshould be thought of as having suffered a minor event, be it transient vascular occlusion, blood pressure changes, short runs of ventricular arrhythmias, or any number of other conditions (3). Whereas most patients suffer no testable harm from such events, some do, and hence the observed higher risk of poor outcomes.
Finally, in our report we referred to detectable troponin within the normal range as "marginal" troponin, indicative of "minor myocardial injury." We believe these terms aid in thinking about these patients, and we would advocate their continued use.
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References
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1. Kontos MC, Shah R, Fritz LM, et al. Implication of different cardiac troponin I levels for clinical outcomes and prognosis of acute chest pain patients J Am Coll Cardiol 2004;43:958-965.[Abstract/Free Full Text]
2. Henrikson CA, Howell EE, Bush DE, et al. Prognostic usefulness of marginal troponin T elevation Am J Cardiol 2004;93:275-279.[CrossRef][Medline]
3. Antman EM. Decision making with cardiac troponin tests N Engl J Med 2002;346:2079-2082.[Free Full Text]
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