Proximal vs. Distal LAD Lesions in ST-Elevation Myocardial Infarction: Insights from ECG and Coronary Angiography

<b>Background:</b> The identification of the left anterior descending (LAD) artery as the culprit vessel in ST-segment elevation myocardial infarction (STEMI) is critical for rapid decision-making and targeted reperfusion. Electrocardiography (ECG) remains a vital diagnostic tool, especially in cases of no prior clinical or imaging data. This study evaluates the accuracy of 12-lead ECG in identifying LAD involvement and occlusion level, while examining the prognostic significance of proximal versus distal LAD lesions in the era of modern reperfusion techniques. <b>Methods:</b> Data from 382 patients with STEMI were analyzed, focusing on the correlation between specific ECG patterns, particularly ST-segment elevation in aVL and aVR, and coronary angiographic findings. The predictive performance of ECG in localizing proximal LAD lesions was assessed through sensitivity, specificity, and predictive values. Clinical outcomes at 30 days and 2.5 years were compared between patients with proximal and distal LAD occlusions. <b>Results:</b> ST-segment elevation ≥ 0.5 mm in aVL or elevation in aVR, when associated with elevation in at least two contiguous precordial leads (V2-V4), demonstrated good sensitivity and predictive value for proximal LAD occlusion. Contrary to earlier studies, no significant difference in short- or long-term clinical outcomes was observed between proximal and distal LAD occlusion groups, possibly reflecting improvements in percutaneous coronary intervention (PCI) techniques and modern pharmacotherapy. <b>Conclusions:</b> The 12-lead ECG remains a valuable tool for identifying LAD as the culprit artery and approximating lesion location. However, in the era of advanced reperfusion therapy, the prognostic value of proximal LAD occlusion may be less pronounced than previously thought. These findings support a nuanced interpretation of ECG in guiding acute management without overestimating the long-term prognostic weight of lesion location alone.