- Persistent ST elevation following an acute myocardial infarction.
- Following an acute STEMI, the ST segments return towards baseline over a period of two weeks, while the Q waves persist and the T waves usually become flattened or inverted.
- However, some degree of ST elevation remains in 60% of patients with anterior STEMI and 5% of patients with inferior STEMI.
- The mechanism is thought to be related to incomplete reperfusion and transmural scar formation following an acute MI.
- This ECG pattern is associated with paradoxical movement of the ventricular wall on echocardiography (ventricular aneurysm).
ECG Features of LV Aneurysm
- ST elevation seen > 2 weeks following an acute myocardial infarction.
- Most commonly seen in the precordial leads.
- May exhibit concave or convex morphology.
- Usually associated with well-formed Q- or QS waves.
- T-waves have a relatively small amplitude in comparison to the QRS complex (unlike the hyperacute T-waves of acute STEMI).
The pattern of persistent anterior ST elevation (> 2 weeks after STEMI) plus pathological Q waves has a sensitivity of 38% and a specificity of 84% for the diagnosis of ventricular aneurysm.
Ventricular aneurysms predispose patients to an increased risk of:
- Ventricular arrhythmias and sudden cardiac death (myocardial scar tissue is arrhythmogenic).
- Congestive cardiac failure.
- Mural thrombus and subsequent embolisation.
The following conditions may cause an LV aneurysm:
- Acute myocardial infarction (by far the most common).
- Cardiac infection.
- Congenital abnormalities.
Differentiation from acute STEMI
In patients presenting with chest pain and ST elevation on the ECG it is vital to be able to be able to distinguish between LV aneurysm (“old MI”) and acute STEMI.
Factors favouring left ventricular aneurysm
- ECG identical to previous ECGs (if available).
- Absence of dynamic ST segment changes.
- Absence of reciprocal ST depression.
- Well-formed Q waves.
Factors favouring acute STEMI
- New ST changes compared with previous ECGs.
- Dynamic / progressive ECG changes — the degree of ST elevation increases on serial ECGs.
- Reciprocal ST depression.
- High clinical suspicion of STEMI — ongoing ischaemic chest pain, sick-looking patient (e.g. pale, sweaty), haemodynamic instability.
Other discriminating features
The ratio of T-wave to QRS complex amplitude has been proposed as an additional means of differentiating between LV aneurysm and acute STEMI:
- T-wave/QRS ratio < 0.36 in all precordial leads favours LV aneurysm.
- T-wave/QRS ratio > 0.36 in any precordial lead favours anterior STEMI.
Anterior Left Ventricular Aneurysm:
- Minimal ST elevation in V1-3 associated with deep Q waves and T-wave inversion.
- This is a LV aneurysm secondary to a prior anteroseptal STEMI.
Inferior Left Ventricular Aneurysm:
- Old inferior STEMI with persistent ST elevation (LV aneurysm morphology).
This ECG is reproduced from Dr Smith’s ECG Blog.
Blog posts on LV aneurysm:
- Left ventricular aneurysm vs. acute anterior STEMI from EMS-12 lead.
- Some more cases of left ventricular aneurysm from Dr Smith’s ECG Blog.
Relevant pages from the ECG library:
- Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.
- Edhouse J, Brady WJ, Morris F. ABC of clinical electrocardiography: Acute myocardial infarction-Part II. BMJ. 2002 Apr 20;324(7343):963-6. Review. PubMed PMID: 11964344; PubMed Central PMCID: PMC1122906. Full text.
- Phibbs BP. Advanced ECG: Boards and Beyond (second edition). Elsevier 2006.
- Smith SW. T/QRS ratio best distinguishes ventricular aneurysm from anterior myocardial infarction. Am J Emerg Med. 2005 May;23(3):279-87. PubMed PMID: 15915398.
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice (6th edition), Saunders 2008.