Activate or Wait – 008

52-year-old male, previously well, one hour of central chest pain radiating to the back. BP 80/45.

We are 10 minutes from your tertiary centre.

Would you activate your cath lab/STEMI protocol?

ECG interpretation

Diffuse subendocardial ischaemia due to oxygen supply-demand mismatch. This ECG pattern is rarely caused by acute coronary occlusion

  • Widespread ST depression in leads V2-6, I, II, III, aVF
  • Reciprocal ST elevation in aVR
  • No Q waves
  • No ST elevation in V1-2 that would suggest septal infarction

ST elevation in aVR is a reciprocal change to the widespread ST depression of subendocardial ischaemia, usually most prominent in I, II and V4-6. This is the same ECG pattern seen in patients with a positive stress test.

Oxygen supply-demand mismatch causing subendocardial ischaemia can be due to both cardiac and/or non-cardiac causes:

  • Severe triple vessel disease
  • LMCA or LAD insufficiency
  • Hypotension
  • Hypoxia
  • ROSC post cardiac arrest

Patients will often have a combination of the above – shock due to sepsis or hypovolaemia may unmask underlying coronary artery insufficiency. Examine other leads closely for changes suggestive of concurrent occlusion myocardial infarction (OMI):

  • ST elevation in V2-4 suggestive of anterior OMI
  • Isolated ST elevation in lead III suggestive of inferior OMI (Aslanger pattern)
  • ST depression maximal in V1-3 that suggests posterior OMI

In the absence of these above changes, acute coronary occlusion is rarely the cause of this ECG pattern. These authors would suggest cardiology review on arrival and strong consideration of non-occlusive causes of ST elevation in aVR. Accredited bedside echo may be useful in guiding initial workup.


Key finding:

Evidence of dissection flap and severe aortic regurgitation


  • Left Main Coronary Artery – Normal
  • Left Anterior Descending Coronary Artery – Normal
  • Left Circumflex Coronary Artery – Normal
  • Right Coronary Artery – Normal
  • Aortogram – Evidence of dissection flap and severe aortic regurgitation


  1. CTS referral made urgently
  2. Patient transferred to CT then to OT
Clinical Pearls
  • In patients with suspected ACS, ST elevation in aVR and diffuse ST depression warrants early discussion with cardiology and prompt (within 24-48 hours) angiography, but in the absence of ST elevation elsewhere, is usually NOT indicative of occlusion
  • Always consider and correct non-cardiac causes of hypotension and hypoxia



  • Harhash et al. aVR ST Segment Elevation. aVR ST Segment Elevation: Acute STEMI or Not? Incidence of an Acute Coronary Occlusion. Am J Med. 2019 May;132(5):622-630. DOI: 10.1016/j.amjmed.2018.12.021
  • Desch et al. Angiography after Out-of-Hospital Cardiac Arrest without ST-Segment Elevation. N Engl J Med 2021; 385:2544-2553. DOI: 10.1056/NEJMoa2101909

Further reading

Online resources


EKG Interpretation

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

MBBS (Hons), BMSci (Hons). Cardiology Registrar at Royal Perth Hospital in Perth, Australia. Graduate of The University of Western Australia in 2016 with Honours and completed Basic Physician Training with the RACP in 2021. Passion lie in cardiac imaging and electrophysiology.

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