The following are key points to remember about this position paper on perioperative myocardial injury and infarction in patients undergoing coronary artery bypass graft (CABG) surgery:

1. Coronary artery disease (CAD) is one of the leading causes of death and disability in Europe and worldwide. For patients with multivessel CAD, CABG surgery is of proven symptomatic and prognostic benefit.
2. The aim of this European Society of Cardiology (ESC) Joint Working Groups position paper is to provide a set of recommendations to better define the level of cardiac biomarker elevation following CABG surgery at which perioperative myocardial injury (PMI) should be considered prognostically significant, and therefore prompt further clinical evaluation.
3. Type 5 myocardial infarction (MI) has been defined in the Third Universal Definition of MI as an elevation of cardiac troponin (cTn) values >10× 99th percentile upper reference limit (URL) during the first 48 hours following CABG surgery, in patients with normal baseline cardiac troponin (cTn) values (<99th percentile URL) together with either: (a) new pathological Q waves or new left bundle branch block, or (b) angiographic documented new graft or new native coronary artery occlusion, or (c) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality.
4. In general, Type 5 MI is mainly due to an ischemic event arising from either a failure in graft function, an acute coronary event involving the native coronary arteries, or inadequate cardioprotection.
5. This position paper recommends that for patients with a baseline cTn <1× URL, isolated elevations of “standard” cTn assays (cTnT ≥7× URL and cTnI ≥20× URL) within the 48-hour postoperative period (in the absence of ECG/angiographic or other imaging evidence of MI), may be indicative of prognostically significant PMI, and require further clinical evaluation to determine whether there is evidence for Type 5 MI.
6. It is important to note that isolated elevations in cTn below these thresholds may still be clinically significant, but their impact on post-CABG mortality appears to be small.
7. There is limited evidence from clinical studies comparing strategies on how best to manage either prognostically significant PMI or Type 5 MI following CABG surgery. The key issue in the immediate postoperative period is to identify patients with regional ischemia due to graft-failure or an acute coronary event in the native coronaries, as this group of patients may benefit from urgent revascularization.
8. For nongraft-related PMI, there is currently no specific therapy available—only general supportive measures.
9. Once coronary angiography is performed following CABG in cases of suspected graft failure, the treatment strategy (conservative vs. revascularization) depends on many factors, and the decision needs to be made in close consultation with the Heart Team (intensivists, surgeons, and cardiologists). These factors include the coronary anatomy, graft occlusion vs. native vessel occlusion, extent of myocardial ischemia, extent of viable myocardium, clinical symptoms, hemodynamic status and inotrope support, and age and comorbidities.
10. Additional studies are needed to establish thresholds, especially for high-sensitivity cTnT elevations, which can be used in conjunction with clinical features and imaging findings, to predict those patients with regional ischemia or graft failure. Furthermore, studies are required to better define the role of coronary angiography post-CABG surgery to detect early graft failure.

Keywords: Biomarkers, Bundle-Branch Block, Cardiac Surgical Procedures, Coronary Angiography, Coronary Artery Bypass, Coronary Artery Disease, Coronary Occlusion, Electrocardiography, Hemodynamics, Myocardial Infarction, Myocardial Ischemia, Myocardial Reperfusion Injury, Myocardial Revascularization, Myocardium, Troponin

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