Perspective:

The following are 10 points to remember about the new definition of clinically relevant myocardial infarction (MI) after coronary revascularization:

1. Myocardial infarction (MI) in patients undergoing coronary revascularization is associated with an adverse outcome.

2. There are numerous definitions of periprocedural MI, but they do not carry identical clinical significance.

3. The universal definition for MI designates postprocedural troponin elevation thresholds for defining percutaneous coronary intervention (PCI)-related MI (type 4a, cardiac troponin [cTn] >5 x the 99th percentile of the upper reference limit [URL]) and coronary artery bypass grafting (CABG)-related MI (type 5, cTn >10 x the 99th percentile of the URL).

4. Myonecrosis after PCI may be associated with angiographic complications or occur in the absence of such complications.

5. Myonecrosis is also associated with the extent and complexity of coronary atherosclerosis, and the observed association between the degree of myonecrosis and long-term outcome may simply reflect the extent of underlying coronary disease burden. This implies that the biomarker elevation may be a marker rather than mediator of long-term mortality and morbidity.

6. cTn is a more sensitive and specific biomarker for myonecrosis than creatine kinase-myocardial band (CK-MB), but it may not be the optimal biomarker for defining post-PCI MI.

7. The association between biomarker elevation and post-PCI outcome is not linear, and only greater degrees of elevation have been associated with increased mortality. Biomarker elevation strongly associated with mortality has generally been CK-MB >8-10 x upper limit of normal (ULN).

8. A magnetic resonance imaging-based study suggested that changing the cTn I threshold for MI diagnosis to 40 x the 99th percentile URL would greatly enhance specificity (93%) without reducing sensitivity (100%).

9. The authors recommend that post-PCI, an elevation in CK-MB >10 ULN should be used as the preferred biomarker definition of MI. If troponin is used, a threshold of >70 x ULN should be used.

10. In patients undergoing CABG, early biomarker release (occurring within 1 hour post-CABG) may be a meaningful predictor of in-hospital mortality, while elevation in later samples (with 48 hours post-CABG) appears to be a stronger predictor of long-term mortality. The authors support the use of same degree of biomarker elevation to define MI in both the PCI and CABG population.