Middle-aged patient presenting with chest pain. Describe the ECG.

TOP 100 ECG QUIZ LITFL 034

Describe and interpret this ECG

ECG ANSWER and INTERPRETATION

Main Abnormalities

The ECG changes are partially masked by the presence of a right bundle branch block, but there is clear evidence of anteroseptal STEMI:

  • Gross ST elevation in V1-3 (~ 5mm in V2)
  • Convex ST elevation in I and aVL
  • Reciprocal ST depression and T wave inversion in the inferior leads (II, III, aVF)

CLINICAL PEARLS

Predicting the Site of LAD Occlusion

This ECG demonstrates some markers of a very proximal LAD occlusion, involving the two most proximal branches of the LAD — the first septal branch (S1) and the first diagonal branch (D1).

Coronary Anatomy LAD
Signs of occlusion proximal to S1

Signs of basal septal involvement:

  • New RBBB — occurs due to septal infarction
  • ST elevation in V1 > 2.5 mm
  • ST elevation in aVR 
  • ST depression in V5
Signs of occlusion proximal to D1

Signs of high lateral involvement:

  • ST elevation in aVL
  • Inferior reciprocal ST depression > 1 mm 

This patient arrived by ambulance following an out-of-hospital VF arrest and was taken straight to the cath lab where he was found to have a complete ostial occlusion of his LAD.


A Common Pitfall 

This STEMI pattern is occasionally missed, when clinicians erroneously attribute the ST segment changes in V1-3 to RBBB alone.

However, the two patterns are quite different:

  • Typical RBBB will have discordant ST depression and TWI in V1-3
  • Superimposed septal STEMI will lead to ST elevation, Q wave formation, loss of the initial R wave and inversion of only the terminal portion of the T wave

Typical RBBB

RBBB example V1

RBBB + STEMI

RBBB and STEMI



TOP 100 ECG SERIES


Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) 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

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