Activate or Wait – 009

81-year-old female with three hours of central, crushing chest pain. Background of hypertension, heavy smoker.

We are 10 minutes from your tertiary centre.

Would you activate your cath lab/STEMI protocol?

ECG interpretation

Anteroseptal STEMI

  • Concordant ST elevation in leads V2-4, I and aVL — note the presence of right bundle branch block (RBBB)
  • Reciprocal concordant ST depression in inferior leads II, III, aVF
  • Evolving Q waves in aVR, aVL and V1-2

Concurrent left anterior fascicular block (left axis deviation) in this case indicates a bifascicular block. Although this may be pre-existing, a new bifascicular often accompanies a proximal LAD occlusion, as the right bundle branch and left anterior fascicle are supplied by a proximal septal branch of the LAD.

ST elevation in anterior leads here is prominent, however in the presence of a right bundle branch block, any degree of concordant ST elevation is highly concerning for occlusion myocardial infarction (OMI).


Key finding:

40% occlusion of proximal LAD – likely plaque rupture with thrombus but no occlusive disease.


  • Left Main Coronary Artery -Normal
  • Left Anterior Descending Coronary Artery – 40% after LADD2
  • Left Circumflex Coronary Artery – 30% proximal
  • Right Coronary Artery -Dominant, irregular
  • Left Ventriculogram -anterior hypokinesis with mild LV impairment

Likely plaque rupture LAD with thrombus but no occlusive disease

  1. Medical management with 12 months dual antiplatelet therapy
  2. Aggressive cardiovascular risk factor management.
  3. Admit to CCU
Clinical Pearls
  • Whilst there is no evidence-based equivalent of “Sgarbossa criteria” to diagnose acute coronary occlusion in RBBB, the same principles may be applicable. Concordant ST elevation in any lead should prompt strong consideration of invasive angiography
  • New bifascicular block is highly associated with proximal LAD occlusion and negative outcomes. Raise suspicion for OMI, and look for subtle ST changes which may be more difficult to discern


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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