A Rare Case of Atypical Electrocardiogram Changes in Subtotal Occlusion of the Left Main Coronary Artery.

Acute occlusion of the left main coronary artery (LMCA) is one of the most severe forms of acute coronary syndrome. Besides the typical electrocardiogram changes, it is important to promptly recognize atypical changes and hasten revascularization therapy without delays. By analyzing specific cases, this work revealed that ST-segment elevation in aVR and aVL leads, accompanied by newly developed bifascicular block that cannot be ruled out as pathological, but without ST-segment deviation in the chest leads, highly indicates a rare electrocardiographic manifestation of complete occlusion of the LMCA. On the other hand, subtotal occlusion represents an even rarer scenario.