Troponin I levels can now be measured much more accurately and assays have a greater sensitivity. In Edinburgh, the diagnostic level for acute coronary syndrome was lowered from 0.20 ng/mL to 0.05. As a result, when patients presented with suspected ACS they were more likely to be diagnosed — and a year later were more likely be alive and without recurrent infarction.

How do we know this? Because as the more sensitive test was first being introduced, the lab continued to report the old threshold level for six months. That group of patients with lower (yet not reportable) levels than 0.20 ng/mL fared much worse than those with similar troponin results that were reported as being above the threshold during the implementation phase.

Is this just a recipe for overdiagnosis, or should your institution be adjusting its diagnostic threshold?

We have a lively conversation with Dr. Nicholas Mills, the first author of a paper describing all this in JAMA this week.

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