High Lateral STEMI

ECG Features

  • ST elevation primarily localised to leads I, aVL +/- V2
  • Reciprocal ST depression and/or T wave inversion in inferior leads, most pronounced in lead III
ECG High Lateral STEMI 2
South Africa Flag sign: ST elevation in leads I, aVL and V2, with reciprocal changes best seen in leads III and aVF
Culprit vessels
  • Occlusion of the first diagonal branch (D1) of the left anterior descending artery (LAD) may produce isolated ST elevation in I and aVL
  • Occlusion of the left circumflex artery may cause ST elevation in I, aVL along with leads V5-6.

South African Flag sign

High lateral STEMI is associated with a pattern of ST elevation caused by acute occlusion of the first diagonal branch of the left anterior descending coronary artery (LAD-D1).

With the 4×3 display of the 12-lead ECG, the location of the most impressive ST deviations resemble the shape of the South African flag:

  • ST Elevation: Lead I, aVL, V2
  • ST Depression: Lead III (and inferior leads)
ECG Examples
Example 1
High lateral STEMI South African Flag sign

Example 2
ECG High lateral STEMI 3
ECG High lateral STEMI 3
ECG High lateral STEMI 3 South African Flag sign

Clinical cases


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Associate Professor Curtin Medical School, Curtin University. Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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

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