Case sent in by Alex Bracey, written by Pendell Meyers, edited by Smith:
A male in his 60s woke up from sleep with chest pain radiating to the back with nausea. There was no vomiting, diaphoresis, palpitations, or other associated symptoms. Vitals were within normal limits, and the exam was unremarkable, the patient appeared well.
He arrived in the ED approximately 1 hour after onset of pain. Here is the initial ECG, as well as the prior ECG on file from several months ago which was immediately available:
Presentation ECG interpreted alone:
Sinus rhythm at approximately 60bpm, with normal QRS complex. No pathologic Q-waves. Without the prior ECG for comaparison, the T-waves are not clearly hyperacute. There is slight STE in V3-V5. There is 1-2mm STE in II, III, and aVF with slight J-point depression in aVL and marked, large T-wave inversion in aVL.
If you consider only the ST elevation in the inferior leads out of context, this amount and morphology would not be incompatible with a baseline ECG of a young man with high voltage and diffuse baseline ST elevation.
The ST depression and T-wave inversion in aVL, however, is NOT compatible with a baseline abnormality, and makes the ECG diagnostic of acute coronary occlusion. As has been shown through many prior cases and publications by Dr. Smith, lead aVL holds the key to understanding inferior ST elevation. ST depression in aVL should always be assumed to be due to inferior MI, unless there is: limb lead LVH, WPW, LBBB, paced rhythm, etc. If there are well-formed Q-waves, it could be due to inferior LV aneurysm as well.
For review, see Dr. Smith's study comparing the findings of lead aVL in inferior ACO versus pericarditis, showing almost perfect reliability of aVL in this scenario:
http://www.sciencedirect.com/science/article/pii/S0735675715008189
Although the study did not incorporate a cohort with normal variant inferior ST elevation, it is extremely unusual to have reciprocal ST depression in aVL in this setting.
Comparison with baseline ECG:
The STE in the inferior leads is larger than baseline, but only by a small amount. The inferior T-waves are hyperacute in comparison to the baseline. Although there was a very small negative T-wave at baseline, the STD and large bulky negative T-waves seen on the presentation ECG are clearly new changes and must be taken to be reciprocal evidence of inferior ACO. The precordial leads are basically at baseline, and specifically there is no obvious evidence of posterior or lateral ACO accompanying the inferior ACO.
Case Continued:
The ED physicians were immediately suspicious of inferior STE and reciprocal STD and inverted T wave in aVL. They called the interventional cardiologist and began recording serial ECGs.
Bedside echo was limited but showed no effusion, no obvious wall motion abnormality.
The initial troponin was undetectable (as you would expect for an acute coronary occlusion of less than 2 hours duration).
The patient was taken for emergent cardiac cath and found to have 100% in-stent restenosis of his prior RCA stent (this history was withheld above for educational purposes).
Here are the cath images:
Here are the post-cath ECGs:
Troponin T was first positive approximately four hours after onset of symptoms, and peaked at 2.09 ng/dL approximately 10 hours after onset.
Echo later that day showed EF 59%, with severe hyperkinesis of the basal inferior wall and inferior septum.
A male in his 60s woke up from sleep with chest pain radiating to the back with nausea. There was no vomiting, diaphoresis, palpitations, or other associated symptoms. Vitals were within normal limits, and the exam was unremarkable, the patient appeared well.
He arrived in the ED approximately 1 hour after onset of pain. Here is the initial ECG, as well as the prior ECG on file from several months ago which was immediately available:
What is your interpretation? |
Presentation ECG interpreted alone:
Sinus rhythm at approximately 60bpm, with normal QRS complex. No pathologic Q-waves. Without the prior ECG for comaparison, the T-waves are not clearly hyperacute. There is slight STE in V3-V5. There is 1-2mm STE in II, III, and aVF with slight J-point depression in aVL and marked, large T-wave inversion in aVL.
If you consider only the ST elevation in the inferior leads out of context, this amount and morphology would not be incompatible with a baseline ECG of a young man with high voltage and diffuse baseline ST elevation.
The ST depression and T-wave inversion in aVL, however, is NOT compatible with a baseline abnormality, and makes the ECG diagnostic of acute coronary occlusion. As has been shown through many prior cases and publications by Dr. Smith, lead aVL holds the key to understanding inferior ST elevation. ST depression in aVL should always be assumed to be due to inferior MI, unless there is: limb lead LVH, WPW, LBBB, paced rhythm, etc. If there are well-formed Q-waves, it could be due to inferior LV aneurysm as well.
For review, see Dr. Smith's study comparing the findings of lead aVL in inferior ACO versus pericarditis, showing almost perfect reliability of aVL in this scenario:
http://www.sciencedirect.com/science/article/pii/S0735675715008189
Although the study did not incorporate a cohort with normal variant inferior ST elevation, it is extremely unusual to have reciprocal ST depression in aVL in this setting.
Comparison with baseline ECG:
The STE in the inferior leads is larger than baseline, but only by a small amount. The inferior T-waves are hyperacute in comparison to the baseline. Although there was a very small negative T-wave at baseline, the STD and large bulky negative T-waves seen on the presentation ECG are clearly new changes and must be taken to be reciprocal evidence of inferior ACO. The precordial leads are basically at baseline, and specifically there is no obvious evidence of posterior or lateral ACO accompanying the inferior ACO.
Case Continued:
The ED physicians were immediately suspicious of inferior STE and reciprocal STD and inverted T wave in aVL. They called the interventional cardiologist and began recording serial ECGs.
T=20 mins from presentation: the ST segments in III and aVF show straightening, which further confirms inferior ACO. |
T=30 mins from presentation: STE in the inferior leads increasing. |
T=40 mins from presentation: STD in aVL increasing. Q-waves in III and aVF starting to increase in size and width. |
Bedside echo was limited but showed no effusion, no obvious wall motion abnormality.
The initial troponin was undetectable (as you would expect for an acute coronary occlusion of less than 2 hours duration).
The patient was taken for emergent cardiac cath and found to have 100% in-stent restenosis of his prior RCA stent (this history was withheld above for educational purposes).
Here are the cath images:
The LAD appears patent. What is missing in this picture? |
The RCA is now patent after intervention. |
Here are the post-cath ECGs:
STE resolving, Q waves continuing to form. aVL normalizing. |
Continued normalization. No terminal T-wave inversions yet in the affected leads. |
Echo later that day showed EF 59%, with severe hyperkinesis of the basal inferior wall and inferior septum.
Leads II and III from all ECGs, side by side, showing the progression of changes from baseline to ACO to post-PCI. BL= baseline. Reperfusion was not available as no more ECGs were obtained. |
The progression above shows the morphology changes of ACO over time in this case. Visualize the STE, inflating T-waves, straightening of the ST-segments, all of which contribute to the overall increasing amount of area under the curve of the ST-T segment compared to the QRS complex, which then resolves after intervention.
Side note: We believe that the ratio of "area under the curve" from the J-point to the end of the T-wave (compared to the baseline) to the overall size and width of the QRS complex is a great way to visualize and monitor the ST-T segment changes of acute coronary occlusion. This concept incorporates the subtleties of hyperacute T-waves, proportionality, and is illustrated by almost all cases of ACO on this blog. If it could be quantified by a computer (rather than qualified by the eyes of an experienced electrocardiographer as it is now), I believe it would perform much better than the standard STEMI criteria that is currently recommended by guidelines.
Learning Points:
- Lead aVL almost always holds the key to evaluating subtle inferior STE
- Serial ECGs interpreted by those who know what to look for are invaluable