From the Guidelines
Anterior MI can affect leads V1 and V2, especially if the occlusion is located proximal to the first septal and first diagonal branches of the left anterior descending coronary artery. This is because the spatial vector of the ST segment is directed to the left and laterally, resulting in ST elevation in some or all of leads V1 through V6 1. The location of the occlusion within the left anterior descending coronary artery determines which chest leads are affected, with proximal occlusions resulting in involvement of the basal portion of the left ventricle, as well as the anterior and lateral walls and the interventricular septum.
- Key factors that influence the ECG findings in anterior MI include:
- The location of the occlusion within the left anterior descending coronary artery
- The presence of ST-segment elevation or depression in other leads
- The direction of the ST-segment spatial vector
- In general, anterior MI can result in ST-segment elevation in leads V1 through V6, as well as leads I and aVL, depending on the location and extent of the infarction 1.
- The ECG findings in anterior MI are crucial for localizing the area of myocardial damage and identifying the likely occluded coronary artery, which in turn guides treatment decisions.
From the Research
Anterior MI and Leads V1 and V2
- Anterior MI can affect leads V1 and V2, as these leads are used to diagnose ST-segment elevation in acute anterior wall myocardial infarction 2.
- The 12-lead electrocardiogram (ECG) can be used to define the level of obstruction in acute anterior wall myocardial infarction, with ST-elevation in lead V2 being one of the criteria used to predict a proximal LAD lesion 2.
- ST segment elevation in leads V1-V3 can indicate acute occlusion of an epicardial artery with ongoing transmural ischemia, and these patients should be triaged for emergent reperfusion therapy 3.
- The sensitivity and specificity of the 12-lead ECG in detecting acute MI can be improved by using additional electrodes, such as leads V4R, V5R, V8, and V9 4.
- Anterior MI is associated with a higher risk of myocardial injury and worse outcomes, including all-cause mortality and heart failure hospitalization, compared to non-anterior MI 5.
ECG Patterns in Anterior MI
- ST-elevation in leads V1 and V2 can be indicative of acute anterior wall myocardial infarction 2, 3.
- ST-depression in leads V1-V3 can be indicative of subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries, or supply/demand mismatch 3.
- The ECG should be read along with the clinical assessment of the patient, and comparison to previous ECGs and subsequent ECGs can add to the diagnosis and interpretation in difficult cases 3.