From the Guidelines
ECG leads correlate with specific coronary arteries, helping clinicians identify the location of myocardial ischemia or infarction, with the inferior leads (II, III, aVF) primarily reflecting the right coronary artery (RCA) territory, the anterior leads (V1-V4) corresponding to the left anterior descending (LAD) artery, and the lateral leads (I, aVL, V5, V6) reflecting the left circumflex (LCx) artery territory. The relationship between ECG leads and coronary arteries is as follows:
- Inferior leads (II, III, aVF) correspond to the RCA, which supplies the inferior wall of the left ventricle and the right ventricle 1.
- Anterior leads (V1-V4) correspond to the LAD, which supplies the anterior wall and apex of the left ventricle, as well as the interventricular septum 1.
- Lateral leads (I, aVL, V5, V6) reflect the LCx artery territory, which supplies the lateral wall of the left ventricle 1. Understanding these correlations is crucial for rapid diagnosis and treatment of acute coronary syndromes, as it allows clinicians to quickly determine which coronary artery is likely occluded based on the pattern of ST-segment changes on ECG 1. When ST-segment elevation is present in leads II, III, and aVF, it may indicate occlusion of either the RCA or the LCx, depending on which provides the posterior descending branch 1. Additionally, right-sided chest leads, such as V4R, can be useful in diagnosing right ventricular involvement in the setting of an inferior wall infarction and in making the distinction between RCA and LCx occlusion 1.
From the Research
ECG Leads and Corresponding Coronary Arteries
The relationship between electrocardiogram (ECG) leads and coronary arteries is crucial in diagnosing and treating myocardial infarctions. The following points highlight the corresponding coronary arteries for different ECG leads:
- Inferior STEMI:
- Anterior STEMI:
- Left Main (LM) or Left Anterior Descendent Artery (LAD) occlusion can be identified using vectorial analysis of ST deviation in both frontal and horizontal planes 6
- Lateral STEMI:
- No specific criteria are mentioned in the provided studies for lateral STEMI and corresponding coronary arteries
- Posterior STEMI:
- No specific criteria are mentioned in the provided studies for posterior STEMI and corresponding coronary arteries
- Left Bundle Branch Block (LBBB) and de Winter sign:
- These ECG patterns are associated with specific coronary artery occlusions, but the provided studies do not offer detailed criteria for distinguishing between them 6
Diagnostic Performance of ECG Criteria
The diagnostic performance of ECG criteria for identifying the culprit coronary artery varies:
- Sensitivity and specificity of ECG criteria for RCA occlusion in inferior STEMI: 70-90% sensitivity and 72-94% specificity 2, 4
- Sensitivity and specificity of ECG criteria for LCA occlusion in inferior STEMI: 77-87% sensitivity and 86-100% specificity 5, 3
- Diagnostic accuracy of ECG criteria for LM or LAD occlusion in anterior STEMI: low sensitivity (maximum 60%) and high specificity (maximum 95%) 6