Definitions

• ST elevation primarily localized to leads I and aVL is referred to as a high lateral STEMI.
• It is usually associated with reciprocal ST depression and T wave inversion in the inferior leads.
• Sometimes referred to as the South African Flag sign
  

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 circumflex artery may cause ST elevation in I, aVL along with leads V5-6.

South African Flag sign

High lateral STEMI is associated with 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)

Example ECGs

Example 1

Example 2

Related Topics

• Inferior STEMI
• Lateral STEMI
• Posterior infarction
• Right ventricular infarction

References

• Littmann L. South African flag sign: a teaching tool for easier ECG recognition of high lateral infarct. Am J Emerg Med. 2016 Jan;34(1):107-9.
• Durant E, Singh A. Acute first diagonal artery occlusion: a characteristic pattern of ST elevation in noncontiguous leads. Am J Emerg Med. 2015 Sep;33(9):1326
  

LITFL Further Reading

• ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
• ECG A to Z by diagnosis – ECG interpretation in clinical context
• ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
• 100 ECG Quiz – Self-assessment tool for examination practice
• ECG Reference SITES and BOOKS – the best of the rest

Advanced Reading

• Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric
• Wagner GS. Marriott’s Practical Electrocardiography 12e
• Chan TC. ECG in Emergency Medicine and Acute Care
• Rawshani A. Clinical ECG Interpretation
• Mattu A. ECG’s for the Emergency Physician
• Hampton JR. The ECG In Practice, 6e