The Fourth Universal Definition of Myocardial Infarction

You’ve seen Sepsis-3 – but did you miss MI-4?  Not, unfortunately, a James Bond reference – but the “long-awaited” 2018 Fourth Universal Definition of Myocardial Infarction.

Effectively, the crux of this document is to help specifically describe cardiac injury and differentiate the MI and non-MI causes of troponin elevation. This ties to tweezing out the difference between “myocardial injury” and “myocardial infarction”. “Myocardial injury” simply describes circulating cardiac troponin levels ≥99th percentile, and can be acute or chronic. “Myocardial infarction”, on the other hand, is effectively myocardial injury plus supporting evidence for acute myocardial ischemia.

Exciting, I know!

Finally, to recap, the five (six?) types of myocardial infarction:

• Type 1 – Myocardial ischemia and troponin levels ≥99th percentile resulting from atherosclerosis and thrombosis, encompassing STEMI and NSTEMI.
• Type 2 – Myocardial ischemia and troponin levels ≥99th percentile resulting from thophysiologic mechanisms leading to a mismatch of oxygen supply and demand.
• Type 3 – Sudden death suspected to be from new cardiac ischemia, specifically when cardiac biomarkers are not available.
• Type 4a – Coronary intervention-related MI with troponin levels more than 5 times the 99th percentile, or rising troponin levels, and other supporting evidence for new ischemia within 48 hours of PCI and relating to a specific procedural complication.
• Type 4b – Same criteria as Type 1 MI, but related to stent/scaffold thrombosis, absent a specific procedural complication.
• Type 5 – Effectively Type 4a, but with troponin levels 10 times the 99th percentile, and associated with complications from CABG.

Just keeping up, keeping up.

“Fourth Universal Definition of Myocardial Infarction (2018)”
http://www.onlinejacc.org/content/early/2018/08/22/j.jacc.2018.08.1038