Anterior Myocardial Infarction - ECG
Myocardial infarction affecting the anterior wall may be classically divided into non-STEMI and STEMI infarction. The infarction is visible in some of the V1-V6, I and aVL leads.
In an acute STEMI we find the typical elevations of the ST intervals known as Pardee’s waves in some of the above-mentioned leads. Leads recording the inferior myocardial wall (II, III and aVF) usually show the “mirror” depression of ST intervals. Chest pain with these ECG changes is a clear indication to an acute coronary angiography. In subacute forms of a STEMI, the ST elevations are accompanied by gradual formation of deep Q waves that mark myocardial necrosis. These deep Q waves usually never disappear as they also mark myocardial scar.
STEMI of the anterior wall – we see fully developed Pardee’s waves in leads V1-V4 (red non-dashed line) and only a slight one in V5 (red dashed line).
Non-STEMI infarction is typical with ST depressions and negative T waves in the above-mentioned leads. However, this finding is unspecific and can be present also in a simple cardiac ischemia without myocardial cells necrosis. That is why the diagnosis of a non-STEMI infarction needs the elevated levels of cardiac enzymes. This ECG finding together with chest pain but without positive cardiac enzymes can be evaluated “only” as the unstable angina pectoris.
We see ST interval depressions and negative T waves in leads V1-V6 (red circles). If there is also present the elevation of serum cardiac marker, we have the diagnosis of the anterior wall non-STEMI.