Ventricular Aneurysm

Left ventricular aneurysm occurs usually after LAD OMI and can produce chronic changes on an EKG that complicates later evaluation for ischemia (in the affected leads). The changes are large QS waves followed by ST elevation. Normally after an OMI without ventricular aneurysm, Q waves can form but there is not persistent ST elevation. This tends to occur in around half of patients with an anterior OMI and very few of those with an inferior OMI. For the definition of persistent ST elevation, one needs to wait 2 weeks after the OMI. The morphology of the ST elevation can be concave or convex; the amplitude of the ST elevation can be amplified by tachycardia. Patients may have TWI in the lateral leads. In the inferior leads, patients tend to have Q waves as opposed to QS waves. Because of this, inferior aneurysm can be more difficult to differentiate from acute ischemia. Lateral aneurysmal changes can also occur and may have similar morphology to inferior aneurysms. It is also important to note that these are different from biphasic or inverted T waves of Wellen's syndrome as the T waves of Wellen's syndrome are preceded by R waves. 

To identify acute ischemia in the setting of LV aneurysmal changes, the best method is to identify changes from prior EKG's that show LV aneurysm. However, this is not always available (especially if the patient presents relatively early after an anterior OMI with recurrent chest pain). Additional factors that favor ischemia include dynamic changes during the ED course and reciprocal ST depressions (aneurysmal ST elevation should not have reciprocal ST depressions). Another factor that has been proposed is to compare the T wave amplitude to the QRS amplitude as LV aneurysmal changes should have smaller T waves. A T wave/QRS ratio>0.36 in any lead V1-V4 favors an anterior OMI with only the positive portion of the T wave being counted (negative portion has not been validated). One can also compare the sum of the T wave amplitudes in these leads with the sum of the QRS amplitudes; a value <0.22 indicates aneurysm. Additionally, inverted anterior T waves may become upright as the initial change (pseudonormalization) without being large in amplitude initially. The main exception to these rules is if a patient has a subacute OMI, as the T wave may begin to come down in the process of inversion (see OMI progression page).

Examples:

Further Reading:

litfl.com/left-ventricular-aneursym-ecg-library/ 

http://hqmeded-ecg.blogspot.com/search/label/LV%20aneurysm

http://hqmeded-ecg.blogspot.com/search/label/Inferior%20Aneurysm%20Morphology

http://hqmeded-ecg.blogspot.com/search/label/LV%20aneurysm%20lateral