STEMI/NSTEMI vs. OMI/NOMI

The goal of identifying a STEMI vs. NSTEMI is to rapidly stratify patients who need reperfusion therapy immediately. A STEMI was indicative of a significant occlusion that cardiac catheterization, the gold standard for reperfusion, could resolve quickly. While it's still true that most STEMIs would benefit greatly from reperfusion therapy, not so much for NSTEMIs.

In fact, there are a lot of NSTEMIs that also involves occlusion of a coronary vessels and where reperfusion therapy is essential for decreased morbidity and mortality. For this reason, there's a growing school of thought that instead of classifying unstable MIs as either STEMI or NSTEMI, we should be classifying these unstable MIs as either OMI or NOMI: Occlusive MI, or Non-occlusive MI. An OMI would therefore be one that requires immediate cardiac catheterization, while a NOMI could be treated with catheterization or a more conservative strategy (e.g. medical management).

As the body of literature is still growing on OMI vs. NOMI, we're instead going to link to a number of resources in the #FOAMed world that does a pretty good job of talking about this topic.

Since the criteria of what kind of NSTEMIs would classify as an OMI/NOMI goes beyond the scope of what is covered by this site, we'll instead focus on four ECG findings that might show up on conventional cardiac monitoring.

Wellens Syndrome: Pattern A

Wellens syndrome refers to a pattern of ECGs that occurs while the patient is pain-free. It characteristically has none to minimal ST elevation. In the first pattern (Pattern A), the T waves are biphasic - first positively-deflected, then negatively-deflected (and always in that order). The biphasic T waves are most prominent in leads V2-V3.

Wellens Syndrome: Pattern B

In the second pattern (Pattern B), the T waves are deeply inverted and again, most prominently in leads V2-V3.

Wellens Syndrome classically shows after any incident where the coronary vessels occluded, but then reperfused (e.g. due to a thrombus, vasospasm, etc.). Thus this ECG pattern often indicates that perfusion through the coronary vessels is precarious.

Hyperacute T Waves

Hyperacute T Waves refers to the presence of T waves that are significantly broad and wide. Notice that the area under the T wave is signifcantly out-of-proportion when compared to the preceding QRS complex. While it occurred in leads II and III in the ECG above, hyperacute T waves could occur in any lead. Their presence indicates a potential incoming ST elevation.

De Winter T Waves

De Winter T Waves refers to the pattern of:

  • J-point depression in the precordial leads (V1-V6), followed by
  • Upward ST depression, followed by
  • Tall, symmetric T waves

Notice that there's mild ST elevation in lead aVR. They could be thought of as a subset of Hyperacute T waves.