Hot off the press:  The Fifth Universal Definition of Myocardial Infarction

What are the Universal Definitions of Myocardial Infarction (UDMI)?  This term refers to a series of documents published as a collaboration among several professional societies including the American College of Cardiology, the American Heart Association, and the European Society of Cardiology.  Their purpose is to define and categorize the various forms of acute cardiac disease with a focus on myocardial infarction.  The diversity of cardiac presentations and troponin elevations can be bewildering.  The UDMI attempts to provide clarity.  The fifth edition was published August 28 and can be accessed here.  

How is myocardial infarction defined?

Myocardial infarction is defined as a dynamic troponin trend (rise and or fall) with at least one value above the upper limit of normal, PLUS at least one indicator of ischemia (chest pain, ECG findings, imaging findings).  An abnormal troponin pattern WITHOUT associated indicators of ischemia is defined as acute nonischemic myocardial injury.  These definitions are unchanged from those of the Fourth UDMI.

The numeric categories of MI have been replaced

Type 1 MI is now designated primary MI.

Type 2 MI is now designated secondary MI.

Types 4 and 5 MI are now designated procedure related MI.

Type 3 MI has been eliminated as a category.  Patients with sudden cardiac death suspected to be due to MI (formerly classified as type 3) should be placed in one of the above new categories, based on clinical judgment.  

The binary electrocardiographic classification (STEMI/NSTEMI) has, unfortunately, been retained.

However, the report does acknowledge the significant number of patients with acute coronary occlusions who do not meet STEMI criteria but need an immediate trip to the cath lab nonetheless.  (Such patients are deceptively labeled NSTEMI and are thus deprived of timely reperfusion).  The report also cites several ECG patterns of acute coronary occlusion not meeting STEMI criteria, including hyperacute T waves, reciprocal ST depressions, posterior infarction, South African Flag sign, Aslanger pattern, De Winter T waves, and Sgarbossa sign.  There are more.  I recently covered them in a Blackboard post here.