• Karin Wildi, Tobias Reichlin, Raphael Twerenbold, Fabienne Mäder, Christa Zellweger, Berit Moehring, Fabio Stallone, Jan Minners, Maria Rubini Gimenez, Rebeca Hoeller, Karsten Murray, Seoung Mann Sou, Mira Mueller, Kris Denhaerynck, Tamina Mosimann, Miriam Reiter, Philip Haaf, Bernadette Meller, Heike Freidank, Stefan Osswald, and Christian Mueller.
• Department of Cardiology, University Hospital Basel, Switzerland; Department of Internal Medicine, University Hospital, Basel, Switzerland.
• Int. J. Cardiol. 2013 Oct 9;168(4):4103-10.

BackgroundCurrent guidelines require a change (rise and/or fall) in levels of cardiac troponin (cTn) for the diagnosis of acute myocardial infarction (AMI). It is unknown whether absolute or relative changes provide higher accuracy when using high-sensitivity cTnI assays.MethodsIn a prospective international multicentre study, we assessed the diagnostic accuracy of early absolute and relative changes in cTnI measured with two novel pre-commercial high-sensitivity assays (Siemens and Beckman Coulter) in 943 unselected patients presenting to the ED with suspected AMI. The final diagnosis of AMI was adjudicated using all available data including serial hs-cTnT levels by two independent cardiologists.ResultsThe diagnostic accuracy of absolute changes in the diagnosis of AMI as quantified by the area under the receiver operating characteristics curve (AUC) was very high (e.g. at 2 h, Siemens high-sensitivity cTnI AUC 0.93, 95%Cl 0.90-0.96; Beckman Coulter high-sensitivity cTnI AUC 0.93, 95%Cl 0.90-0.96) and superior to relative changes at all time points (p < 0.001). The results were consistent in clinically important subgroups. Direct comparison of the absolute changes in the two high-sensitivity cTnI assays showed similar accuracy. When combined with the baseline cTnI levels, the difference between absolute and relative changes became much smaller and remained statistically significant only for the Siemens assay.ConclusionsAs single variables early absolute changes in high-sensitivity cTnI levels have significantly higher diagnostic accuracy than relative changes. When combined with the baseline cTn level, reflecting clinical practice, both absolute and relative changes provided very high accuracy with much smaller differences between both approaches.© 2013.

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