Graphical Abstract
Trade-off between early benefits and potential late hazards. 'Rule-out' is a triage category and not a diagnosis. There is a hazard for late major cardiovascular events if the reason for presentation at the Emergency Department has not been addressed appropriately post-discharge.
In this issue of the European Heart Journal,[1] Lowry and co-workers present a secondary analysis from the randomized High-STEACS trial[2] on 41 103 patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). They carefully investigated the value of a single high-sensitivity cTnI (hs-cTnI) concentration below the limit of detection (LoD) measured by the Abbott Architect hs-cTnI assay to safely rule out acute myocardial infarction (MI) in early and late presenters. The findings were tested in 7088 patients from the multi-centre APACE registry where the same cTnI assay was validated in a similar NSTE-ACS population.[3]
The investigators confirm the concept that a very low hs-cTn concentration in blood at baseline enables the 'rule-out' of MI with a sensitivity and negative predictive value (NPV) of 99.4% and 99.7%, respectively, in patients presenting <3 h from onset of symptoms to troponin testing. Not unexpectedly, discriminator sets using higher hs-cTnI concentrations such as limit of quantitation (LoQ), i.e. the concentration that can be measured with an imprecision of <10%, and the sex-specific 99th centile of the upper limit of normal (ULN) were associated with lower sensitivities and NPVs. The latter finding may be surprising, since the 99th centile is a key component of the universal MI definition.
