How to Differentiate Ventricular Aneurysm from Acute MI

Left ventricular aneurysm is an area of infarcted myocardium that bulges outward from the ventricular contour during systole and diastole, and it is a possible complication of acute myocardial infarction (MI). It occurs mainly with occlusions of the left anterior descending artery or of a dominant right coronary artery, due to ischemia and the resulting tissue necrosis.

This complication is characterized by pathological changes in left ventricular contractility and myocardial fibrosis, with related electrocardiographic changes, such as electrically inactive areas and secondary changes of the ST-T complex.

Electrocardiographic Criteria

Let's look at the electrocardiographic criteria for ventricular aneurysm:

ST elevation in at least two contiguous leads
Q or QS waves in at least two contiguous leads accompanying the ST elevation
T waves commonly inverted, biphasic, or of low amplitude
QRS fragmentation may be present
A prominent R wave in aVR (Goldberger's sign) may be present

Here are some examples:

QS complexes in leads V1 to V4, indicating an anteroapical electrically inactive area, with chronic ST elevation. There are diffuse secondary repolarization changes, including biphasic, terminally inverted T waves from V1 to V4, inverted T waves in V5 and V6, and flattened T waves in I and aVL.

*ECG showing QS complexes from V1 to V5, indicating an anteroapical electrically inactive area. Together with this, chronic ST elevation from V1 to V5 suggests a left ventricular aneurysm.*

How to Differentiate Ventricular Aneurysm from Anterior Wall OMI

The repolarization changes characteristic of the left ventricular aneurysm pattern make its electrocardiographic differentiation from acute or subacute OMI involving the anterior wall challenging, especially because of the chronic ST elevation and terminal T-wave inversion.

Faced with this challenge, Stephen Smith developed differentiation criteria based on the ratio between the amplitudes of the T wave and the preceding QRS (T/QRS ratio) and on the ratio between their sums from V1 to V4 (ΣT/ΣQRS ratio). These criteria are shown in the table below, with their respective positive (LR+) and negative (LR-) likelihood ratios for OMI:

Criterion	LR+	LR-
T/QRS ≥ 0.36 in at least one lead from V1 to V4	4.89	0.10
ΣT/ΣQRS ≥ 0.22 (V1 to V4)	2.93	0.12

Acute occlusion of the Left Anterior Descending artery correctly identified with the help of the criteria. Note the T/QRS ratio ≥ 0.36 in V4 and ΣT/ΣQRS ≥ 0.22 (sum from V1 to V4), indicating an evolving anterior wall MI.

In addition to these criteria, serial electrocardiograms are valuable in differentiating between these two diagnoses. Indeed, a static pattern on serial tracings argues against an acute process, whereas dynamic electrocardiographic changes consistent with an evolving MI favor it. The absence of reciprocal changes also argues against attributing the ST elevation to acute infarction. However, it should be emphasized that the clinical picture is the cornerstone in differentiating the two diagnoses, the ECG being a highly valuable complementary test, but complementary nonetheless.