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NSTEMIs

"Some good news, sir...you're not having a heart attack..."


How many of us have either said that or have overheard someone else telling that to the patient after looking at the 12 lead? A "yes" answer from me, for both (unfortunately).


I was a year or so into my paramedic career when I incorrectly told a patient that they were not having a heart attack, After that, I quickly changed the way that I communicated with my patients. The, "Sir, you are not having a heart attack." changed to, "Sir, there are two types of heart attacks and I am only able to check for one of them. From the tests that I can do, it appears that you are not having that type of heart attack. However, the hospital will need to do some additional EKGs and bloodwork to completely rule in/out a heart attack." Lengthy, I know, but at least I wouldn't give false hope if a non-STEMI and elevated troponin was found once at the Emergency Department.


As paramedics, we are trained to recognize ST elevated myocardial infarctions (STEMIs) but we often have little to no training in identifying NSTEMIs (non ST elevated myocardial infarctions). Identifying NSTEMIs can certainly be challenging but I do think that through continuing education every paramedic should dive a little deeper into the topic.

According to a 2021 study (Basit, Malik, Huecker) the incidence of ACS in the United States is 780,000 and of those, approximately 70% will have a NSTEMI. This further engrains the importance of becoming familiar with how some of these patterns present; especially since STEMI and NSTEMI patients can clinically present identically.


Photo Credit: Unknown

If you dust off some (okay, a lot) of those cob webs from paramedic school, you may remember learning about subendocardial and transmural ischemia. Typically, NSTEMIs will occur with subendocardial ischemia. Subendocardial ischemia occurs when the ischemia has only partially extended through the myocardium. Whereas as transmural ischemia represents ischemia that extends through the entire wall of the myocardium.


Now, let's talk about those NSTEMI patterns...


De Winter's T-Waves

De Winter's T-waves are characterized by tall, prominent and symmetrical T-waves in the precordial leads (the "V" leads) with upsloping ST segment depression and reciprocal ST segment elevation in aVR. "Wait, I thought aVR was completely irrelevant on the 12 lead?" You're not alone - me too. aVR is electrically opposite of I, II, aVL, V4 - V6. So, when depression is seen in these leads, we may see some reciprocal elevation in aVR.

De Winter's T-waves occur in approximately 2% of acute LAD occlusions and is treated as a STEMI equivalent. These patients will undergo emergency percutaneous coronary intervention (PCI).




Aslanger Pattern

The 2% of acute LAD occlusions mentioned above may not have been significant enough to get you invested in NSTEMI patterns, but this one certainly may. Aslanger pattern is seen in approximately 13% of Inferior MIs (II, III, aVF) and in approximately 6% of NSTEMIs.


How's it characterized:

  • Isolated ST elevation in Lead III

  • ST depressions in any of V4 - V6 with a positive T-wave

  • The ST segment in V1 > V2


Wellen's Syndrome

Wellen's Syndrome is typically suggestive of left anterior descending (LAD) stenosis but it can actually occur in the left circumflex (LCx) or the right coronary artery (RCA). An interesting piece about Wellen's is that it is typically seen in a pain-free state and may have normal or slightly elevated troponin levels.


Wellen's is characterized by biphasic or deeply inverted T-waves in V2 - V3 and a recent history of chest pain.

Biphasic T-waves. Credit: www.litfl.com
Deeply Inverted T-waves. Credit: www.litfl.com

Wellen's is typically seen once the LAD has been "reperfused." This can occur after the administration of aspirin or nitroglycerin, after the lysis of a clot or following coronary artery vasospasm.


Life in the Fast Lane does a great job of providing the following case on their site (which by the way is an incredible EKG website - check it out if you haven't!)


Pre-hospital 12 lead EKG performed at 1938 hours. Patient was presenting with diaphoresis and chest pain. This is pretty obvious, an Anteroseptal MI (STE in V1 - V3).

Approximately 15 minutes later, the patient is pain-free and the hospital captures a 12 lead and biphasic t-waves are found in V2 - V3 with minimal ST-elevation.


There is a TON of information available on the web regarding NSTEMIs. Hopefully this post provided a little more information and motivation to dig deeper into the content.


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Do you need help with the basics of 12 lead EKG interpretation? If so, check out our YouTube video below and don't forget to subscribe to our channel!

-Pass with PASS, LLC


Sources

Basit H, Malik A, Huecker MR. Non ST Segment Elevation Myocardial Infarction. [Updated 2021 Nov 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513228/


Life in the Fast Lane, www.litfl.com


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