The document discusses differentiating ST elevation myocardial infarction (STEMI) from other causes of ST elevation on an electrocardiogram (ECG). It provides examples of three sample ECGs, describing ECG 1 as showing typical inferior STEMI patterns, ECG 2 as most consistent with pericarditis given its global and concave ST elevation, and ECG 3 showing minimal changes consistent with benign early repolarization. Key factors for differentiation include the magnitude, morphology, distribution of ST elevation, and comparison to previous ECGs. The document emphasizes analyzing ST elevation in the full clinical context and pursuing safe care when in doubt.

1. ST Elevation → is that a STEMI?

2. Recording a 12 lead ECG when I was an
Intern.....

3. Aims
• Physiology of the ST segment
• ECG quiz
• Interpretation of ST elevation

4. A Quiz for you now....

5. The setting...
You’re notified by ambulance of the arrival in 10 minutes of a 56 year
old man with chest pain that started this morning – its now 1530 and after
treatment by them, he’s currently pain free.
They’re not able to send you an ECG at this stage, but they say there’s
ST elevation on their rhythm strip
What actions should we take now?

6. On arrival he’s alert, pain free with normal vital signs.
You’re handed one of the following three 12 lead ECGs
Would you take the same immediate actions for each of them?

7. ECG 1

8. ECG 2

9. ECG 3

10. ECG 2 was the one I was handed…

11. “Code STEMI” activated and patient met and assessed on arrival by ED
staff, Interventional Cardiologist not immediately available
IV x2 and bloods taken
Administered Clopidogrel and Heparin
Taken to coronary catheterisation suite and prepped waiting for
Cardiologist who arrived 5 minutes later...

12. Cardiologist “pattern recognition” read of ECG as he arrived:
“Why am I rushing in here for pericarditis?”
Result?
Normal angiogram
Admitted to CCU, serial high sensitivity troponin 26 and 41
(normal < 10)

13. What causes of ST elevation do you know / look for on the ECG?

14. Causes of ST elevation
• Myocarditis
• Acute Myocardial infarction • Brugada syndrome
• Tako tsubo CM
• Acute Pericarditis • Prinzmetal Angina
• LVH Athlete’s heart syndrome
• Benign Early Repolarisation • Pre-excitation syndrome WPW
• Hyperkalaemia
• Acute intracranial event
• Aortic dissection
• LV Aneurysm

15. Differentiating MI ST elevation from other
causes on the ECG
• Magnitude of the elevation
• Morphology of ST segment
• Distribution of the ST elevation
• Comparison with previous ECGs, serial ECGs and extra leads
• Knowledge/recognition of specific unusual variants like Brugada

16. Magnitude of the elevation
The greater the degree of elevation, the more it’s likely to be an AMI

17. Morphology of ST elevation
• Convex / straight ST elevation more typical of AMI
• Concave shape ST elevation are usually non AMI causes
Convex Concave

18. Typical ST Elevation patterns in AMI

19. Distribution of ST elevation
• ST elevation resulting from vascular occlusion usually demonstrates
a regional or territorial pattern
– Anterior V1-V5
– Anteroseptal V1– 4
– Lateral V5, V6, 1, aVL
– Inferior II, III, aVF
– Posterior V1, V2, V7-9
– Proximal LAD aVR

20. ECG 1
Sinus bradycardia, 54/min with multifocal ventricular ectopy.
Inferior lead STE typical of MI, aVL ST depression

21. Pericarditis ECG features
Usually global low magnitude ST elevation
Concave upward morphology
PR depression can be seen early
T wave changes later (days to weeks)
ST changes resolve fully so not persistent on future ECGS

22. ECG 2
Sinus rhythm 66/min, first degree heart block, global STE mostly upwardly
concave (although V2 + 3 look like hyperacute STEMI segments..) No PR
depression (or elevation in aVR remember) but overall most c/w Pericarditis

23. ECG 3
SR 60 /min with minimal global upwardly concave STE. Most c/w benign early
repolarisation

24. Benign Early Repolarisation
1. ST elevation <2 mm
2. Concavity of initial portion of the ST segment
3. Notching or slurring of the terminal QRS complex
4. Symmetrical, concordant T wave of large amplitude
5. Widespread or diffuse distribution of ST elevation
Does not demonstrate territorial distribution
6. Relative temporal stability, so will be seen on previous ECGs if
available / obtainable

25. Benign Early Repolarisation
Large amplitude T wave
Concave ST elevation
Notching or slurring of J point

26. So ....recapping
• Magnitude of the elevation
• Morphology of ST segment
• Distribution of the ST elevation
• Comparison with previous / serial / extra lead ECGs

27. Take home messages
• Many causes for ST elevation other than MI, so always analyse
within the clinical context (Rule 1: “context is everything”)
• Whenever possible, use previous and serial ECGs
(more data improves quality of interpretation and decision making)
• If in doubt, seek another expert opinion and/or pursue safe cautious
clinical approach to patient care