Troponin testing: an audit in three metropolitan hospitals

To the Editor: In the article by Davey1 no evidence other than deviation from a protocol published months before the study is produced to document the implied inappropriateness of single troponin assays.

Emergency physicians are experienced in assessing undifferentiated chest pain. Acute coronary syndromes are but one cause of presentation to emergency departments (EDs) of patients with chest pain, and indeed are but one cause of elevated serum troponin levels.

Many reasons may justify the “appropriate” ordering of single troponin assays. Some patients present to EDs many hours after their episode of chest pain. A single troponin test may be a very useful and sensitive test for a patient whose chest pain occurred yesterday. How many patients in the study group had their single troponin test done more than 12 hours after their episode of pain? How many patients discharged themselves against medical advice as they were unwilling to wait 6–8 hours for a second blood test to triage their risk for an acute coronary syndrome? How many patients died or were transferred to another hospital? How many patients had their single troponin test ordered in the investigation of a primarily non-cardiac illness, such as sepsis or pulmonary embolism?

I have no doubt that many troponin assays ordered in the study population were inappropriate. But, by failing to conduct an explicit medical record review of those patients whose tests were deemed inappropriate, the author has failed to answer his stated aim of determining if the troponin assay is used appropriately when chest pain is encountered. We are left with no knowledge of whether this problem is small or large.

Finally, does it matter? Are two consecutive negative troponin assays required to triage patients with chest pain? Recently, the Journal published a clinical outcome study that examined the implementation of a chest pain assessment protocol at a metropolitan university teaching hospital in Bankstown, Sydney.2 Patients presenting to the ED with “possibly cardiac” non-traumatic chest pain who were deemed to be low risk did not receive a second, late troponin assay, and yet this approach appeared to be safe.

Those of us who have an interest in the rational use of diagnostic testing for patients with acute coronary syndromes eagerly await the publication of further evidence on this important matter.