High Lateral STEMI and the South Africa Flag Sign: A Case Report Demonstrating ECG- Angiography Correlation, A Bedside Indicator of Life-Threatening Proximal LAD System Occlusion Involving The First Diagonal Branch

A 43-year-old male without traditional risk factors presented with an acute high lateral ST-elevation myocardial infarction (STEMI). The electrocardiogram (ECG) revealed the distinctive 'South Africa Flag' sign. A significantly elevated troponin-I level (25 ng/mL) corroborated extensive myocardial injury. Emergency coronary angiography identified an ostial occlusion of the first diagonal (D1) branch of the left anterior descending artery as the culprit lesion, which was successfully treated with percutaneous coronary intervention (PCI). This case exemplifies the critical importance of recognizing this ECG pattern as an urgent bedside indicator of a life-threatening D1 occlusion.