Left Main Coronary Artery Lesion - ECG

ECG Findings
• ST segment elevation in the precordial leads (V2-V6) and high lateral leads (I, aVL).
• Reciprocal ST segment depressions in the inferior leads (II, III, aVF).
• ST segment elevation in AVR coupled with reciprocal ST depressions may indicate AMI from left main disease.

Significant ST elevation is present in the precordial leads (V2-V6) and high lateral leads (I and aVL) (arrows). In this example, significant Q waves have appeared, signaling infarction (arrowhead).

Clinical Pearls 
1. The left main coronary artery branches into the left anterior descending artery and the circumflex artery.It supplies blood to the ventricular septum and the anterior and lateral aspects of the left ventricle, usually sparing the posterior and inferior portion, which is most often served by the right coronary artery.

2. Normal R-wave progression (increasing R-wave amplitude across the precordial leads) may be interrupted.
3. Risk of cardiogenic shock is high since so much of the left ventricle is served by the left main coronary artery.
4. A left main coronary thrombosis is also known as the “widowmaker lesion.”
5. Isolated ST segment elevation in lead aVR may also indicate acute myocardial ischemia from left main coronary artery disease.