NSTEMI, the catch-all diagnosis

The diagnostic label NSTEMI (non ST segment elevation MI) tends to be inappropriately applied to many cases of acute troponin elevation in the absence of electrocardiographic ST segment elevation. The result has been that NSTEMI has become a catch all diagnosis, to the point of being devoid of meaning.  Actually, troponin elevations without ST segment elevation have a differential diagnosis including NSTEMI, type 2 MI, takotsubo cardiomyopathy,  PE, and acute nonischemic myocardial injury. This last one is frequently seen in sepsis and other non cardiac critical illnesses. Labeling such instances as NSTEMI is problematic because it can lead to inappropriate and potentially harmful treatments such as systemic anticoagulation.

This problem has been addressed in the literature. The paper linked below from JAMA is somewhat dated but useful.

Increasingly Sensitive Assays for Cardiac Troponins

Figure 1  from the paper is a proposed algorithm.

A good general resource, one with which all internists should be familiar, is the following,

Fourth Universal Definition of Myocardial Infarction (2018)

The JAMA article was published before the most recent addition of the universal definition. It contains references to the third universal definition, now out of date. I should also point out that although not explicitly addressed in the fourth universal definition one should not conflate type 2 MI with NSTEMI, as the latter term implies ACS. Thus terms like “ type 2 NSTEMI”  should be discouraged.