– A 73 yo M calls 911 for chest pain. Described as a burning sensation 1 hour prior, 10/10 non radiating.
PMH- HTN and previous MI more than 10 years ago. Initially, he was refusing transport to the ED.
V/S – BP 170/120, HR- 70, RA SPO2- 92%, RR-12, BGL- 130. No associated dyspnea, N/V or diaphoresis
Medics captured 12 lead:
Sinus rhythm with 1st degree block.
Obvious pathologic Q wave in AVL with STE and reciprocal STD in all 3 Inferior leads.
STE of ~2mm in AVR
STE of ~2mm in V1
V1- V3 all present with well-formed Q/QS waves with STE and moderate sized T waves.
V5 and V6 have 2-3mm STD with horizontal, flat ST segments
V1- V3 present with somewhat of an LV Aneurysm appearance:
(QS-wave means a Q-wave with no R-wave at all, in contrast to a QR-wave or qR-wave).
This is “Left Ventricular Aneurysm (LVA)” morphology and is due to Old Completed (Transmural) Anterior MI, which often results in an LV aneurysm and manifests on the ECG as “persistent ST elevation after old MI.”
The T-wave may be upright or inverted.
LVA has a small T-wave (small upright or small inverted — not tall/wide nor inverted and deep/wide).
Dr. Steven Smith
So, the key to differentiating LVA vs Acute LAD Occlusion is in the T waves!
In our presenting ECG, the T waves are upright and of moderate size. Is there a way to tell the difference? Yes!
We will use the validated rule of T/QRS ratio:
T/QRS ratio best distinguishes ventricular aneurysm from anterior myocardial infarction – ScienceDirect
Electrocardiographic criteria to differentiate acute anterior ST-elevation myocardial infarction from left ventricular aneurysm – ScienceDirect
The rules – 1st, there must be STE. 2nd – The DDX must only include LVA vs LAD Occlusion.
This will not apply to the Early Repol formula: Dr. Smith’s ECG Blog: 12 Example Cases of Use of 3- and 4-variable formulas, plus Simplified Formula, to differentiate normal STE from subtle LAD occlusion (hqmeded-ecg.blogspot.com)
In V1-V4 – from the isoelectric line, measure to the peak of the T wave. Divide this by the depth of the QRS.
- T-wave/QRS ratio < 0.36 in all precordial leads favors LV aneurysm
- T-wave/QRS ratio > 0.36 in any precordial lead favors anterior STEMI
In Fig. 2 we see in V2, the peak of the T is about 4mm, the QRS is about 9mm. 4/9= about 45%. More than enough to say this is acute and not from the pt’s previous MI. Although not needed – V3 also shows greater than the required 36% also confirming an acute OMI.
This image – borrowed from Dr. Smith’s ECG Blog – Dr. Smith’s ECG Blog: LV aneurysm anterior (hqmeded-ecg.blogspot.com) shows what a “normal” LV Aneurysm looks like. Notice the STE in the Anterior leads that have much smaller T waves compared to the QRS.
Cath Lab activation from the field. ED 12 Lead captured:
– There is much less baseline wander seen here but it does appear the STD in the Inferior leads has gotten deeper as well as the STE in AVL increased
– The STE in the Anterior leads are obviously greater and now has extended into V4
– Also notice the R wave voltage in V4 has been nearly obliterated, the ST-T segment has a very straight “board like” appearance that almost always indicates acute ischemia.
– The STE in BOTH AVR and V1 have increased.
– The STD in V5 has resolved but persists in V6.
See Fig. 4 for the formula applied here:
If the initial tracing wasn’t convincing enough, this should leave no doubt of a very large ongoing acute occlusion.
It’s worth mentioning here the value of the pathologic Q wave:
STEMIs associated with Q waves indicate a larger infarct and predict a poorer overall outcome.
This is shown in both clinical studies, as well as cMR imaging studies.
Up to 50% of patients with an LAD occlusion develop an anterior Q wave within the first hour of symptoms
Another study found that almost 40% of patients presenting with STEMI, with symptom onset < 6 hours prior, had Q waves
T wave inversion may be a better sign for predicting duration of ischemia. In patients presenting with STEMI, the presence of Q waves seemed to predict the area of myocardium at risk, whereas T wave inversions were better at predicting the duration of ischemia.
I was asked if the STE seen in AVR could represent a Left Main Occlusion.
The short answer is no. A LM Occlusion nearly always presents with Cardiogenic shock and/or cardiac arrest. We simply cannot live with an occluded Left Main Artery.
What is possible is either severe multivessel disease or LM Stenosis.
Predictive Value of STE in aVR:
In the context of widespread ST depression + symptoms of myocardial ischemia:
- STE in aVR ≥ 1mm indicates proximal LAD / LMCA stenosis or severe 3VD
- STE in aVR ≥ 1mm predicts the need for CABG
- Absence of ST elevation in aVR almost entirely excludes a significant LMCA lesion
In the context of anterior STEMI:
- STE in aVR ≥ 1mm is highly specific for LAD occlusion proximal to the first septal branch
In patients undergoing exercise stress testing:
- STE of ≥ 1mm in aVR during exercise stress testing predicts LMCA or ostial LAD stenosis
Magnitude of ST elevation in aVR is correlated with mortality in patients with acute coronary syndromes:
- STE in aVR ≥ 0.5mm was associated with a 4-fold increase in mortality
- STE in aVR ≥ 1mm was associated with a 6- to 7-fold increase in mortality
- STE in aVR ≥ 1.5mm has been associated with mortalities ranging from 20-75%
Fig. 5 shows PCI results.
Acute thrombotic occlusion of the ostial LAD with severe stenosis of the LCx and 100% occlusion of the RCA, s/p PCI with 2 DES and an Impella insertion for cardiogenic shock.