Early Diagnosis of Myocardial Infarction Using Absolute and Relative Changes in Cardiac Troponin Concentrations
How do absolute changes in high-sensitivity cardiac troponin T (hs-cTnT) concentrations impact diagnostic accuracy in the early diagnosis of acute myocardial infarction (AMI), when compared to relative changes, and does the combination of absolute and relative change increase accuracy?
The Advantageous Predictors of Acute Coronary Syndromes Evaluation study is a prospective, international, multicenter study, in which hs-cTnT was measured with three novel assays at presentation and after 1 and 2 hours (both in a blinded fashion) in 830 unselected patients with suspected AMI. Receiver operating characteristic (ROC) curves were constructed to assess the diagnostic accuracy for the diagnosis of AMI for absolute and relative changes within the first hour and within the first 2 hours after presentation alone and in combination with each other.
The area under the ROC curves of the baseline values for all three assays to diagnose AMI were similar (0.94). Furthermore, the area under the ROC curve for diagnosing AMI was significantly higher for 1- and 2-hours absolute (vs. relative hs-Tn changes) for all three assays (p < 0.001). The combination of absolute and relative changes, versus absolute values alone, did provide small incremental benefit for hs-cTnT, but not for hs-cTnI.
Compared to relative hs-Tn changes, absolute changes have significantly higher diagnostic accuracy in the early diagnosis of AMI. The combination of absolute and relative changes provides only a small incremental benefit for hs-cTnT assays (and not for hs-cTnI assays).
The results from this prospective observational study corroborate findings from other studies about the comparative diagnostic accuracy of absolute and relative hs-cTnT concentrations in the early diagnosis of AMI. Absolute changes have significantly higher diagnostic accuracy and outperform relative changes; the combination of absolute and relative offers alone a small incremental benefit for hs-cTnT assays.
Keywords: Myocardial Infarction, Acute Coronary Syndrome, Biological Markers, Early Diagnosis, Troponin T, ROC Curve
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