High Lateral STEMI

ECG Features

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

Example 2

Related Topics

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

Clinical cases

• ECG Case 121

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
  

Advanced Reading

Online

• Wiesbauer F, Kühn P. ECG Yellow Belt online course: Become an ECG expert. Medmastery
• Wiesbauer F, Kühn P. ECG Blue Belt online course: Learn to diagnose any rhythm problem. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog.

Textbooks

• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Hampton J. The ECG Made Practical 7e, 2019
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography 1e, 2009
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Mattu A, Brady W. ECG’s for the Emergency Physician Part I 1e, 2003 and Part II
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004
• Smith SW. The ECG in Acute MI. 2002 [PDF]

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