Cardiac Troponins T and I: Reproducible Discrepancies in the Clinical Setting

Abstract

To the Editor: The universal definition of myocardial infarction includes the increase and/or decrease in cardiac biomarkers, with at least 1 value greater than the 99th-percentile upper reference limit, concurrently with evidence of myocardial ischemia and corresponding clinical symptoms, electrocardiographic changes, or imaging evidence (1). Among cardiac biomarkers, cardiac troponins, including cardiac troponin I (cTnI)1 and cardiac troponin T (cTnT), have become the gold standard. Several noncardiac etiologies for increases in cardiac troponins have been described, however (2), and discordant values for cTnT and cTnI have been encountered in the clinical setting. The aim of our study was to systematically compare a cTnT assay and a cTnI assay with regard to discrepant values. This study was conducted in accord with the World Medical Association Declaration of Helsinki (3). We used the Architect cTnI STAT Troponin-I assay (Abbott Diagnostics) and the new high sensitive troponin T (hsTnT) assay (Troponin T hs) on the Modular Analytics system (Roche Diagnostics) to make 9004 simultaneous cTnI and cTnT measurements on 3995 patients and then analyzed the data. Because we were concerned about major discrepancies, we used 0.032 μg/L as the cutoff value for both the cTnI and hsTnT measurements. After applying this cutoff to our …