Perioperative myocardial injury evidenced by cardiac biomarker elevation is common after cardiac surgery.1,2 The fourth universal definition of myocardial infarction (UDMI)2 defines perioperative or Type 5 myocardial infarction as an elevation of cardiac troponin (cTn) of 10× the 99th percentile upper reference limit (URL) combined with (i) new pathological Q waves on electrocardiogram (ECG), (ii) flow-limiting angiographic complications, and/or (iii) new loss of viable myocardium on imaging.2 While valuable as a definition, these criteria are not to be used to indicate the need for invasive workup of post-operative patients.
For clinical decision-making, numerous algorithms by the European Society of Cardiology (ESC) joint working group,1 the Society for Cardiovascular Angiography and Interventions,3 and the Academic Research Consortium-24 have been proposed utilizing the best available evidence on the relationship between cTn levels and mortality or evidence of myocardial ischaemia by employing a combination of different cTn cut-off values with additional criteria similar to the above-mentioned definition of Type 5 myocardial infarction. These algorithms propose an isolated elevation in cTn levels within the first 48 h after surgery of ≥70× URL or elevations of cTn levels ranging from >10× URL to ≥35× URL combined with at least one of the above-mentioned additional abnormalities as criteria necessitating further workup, in most cases invasive coronary angiography (ICA). Several limitations exist for the cTn cut-off values used in these definitions: (i) they have either been arbitrarily chosen, as in the case of the UDMI,2 or (ii) are based solely on prognostic associations, which are not necessarily suitable to inform further clinical decision-making regarding revascularization.