A 40-something woman had sudden chest pain. She called 911. This prehospital ECG was recorded:
Here are limb leads:
Here are precordial leads:
This is of course diagnostic of an acute coronary occlusion MI (OMI) that also meets STEMI criteria.
But which myocardial walls are affected?
Posterior (as manifested with T-wave inversion)
Lateral (subtle ST elevation)
Is there also RV MI? Can you tell from this ECG? (hint: no, you can’t tell from this ECG)
When this was shown to me, I said “Activate the Cath Lab.”
The providers had been uncertain until I gave my opinion, but then went ahead and activated.
Then this was recorded in the ED 10 minutes after the first:
|Now there is massive STE
Many inferior MI are associated with RV MI. Is there RV MI here?
The left sided 12-lead is imperfect for diagnosing RV MI. The same week this case arrived, I submitted a revision of a manuscript that is under consideration in which we found:
1) ST depression in lead I is useless in differentiating RCA occlusion with vs. without RV MI
2) ST elevation in V1 is pretty specific (~83%) for RV MI in the setting of inferior MI.
3) ST elevation in V1 is not sensitive for RVMI, and is very insensitive if there is ST depression in V2 (posterior MI pulls the ST segment down and negates any ST elevation that might otherwise be present in V1 during RV MI).
So, if you have the time while waiting for the angiography team, you should record a right sided ECG, because RV MI have higher mortality, are more likely to be hypotensive, and are more nitroglycerin sensitive.
So we recorded a right sided ECG:
|V1 = V1R = same position as V2 on left side ECG
V2 = V2R = same position as V1 on left side ECG
V3 = V3R
Now you can see that there is much STE in V4R-V6R, diagnostic of RV MI.
At angiogram, there was a culprit just distal to the RV marginal branch (not proximal), and so it was called a mid-RCA occlusion. By the ECG, it should be a proximal occlusion, proximal to the RV marginal branch.
I saw this result the next day and it perplexed me, so I inquired with the cardiologists.
Today, they viewed the angiogram and concluded that the thrombus at the mid RCA must have extended proximally from the culprit ruptured plaque, extending proximal to the RV marginal branch and temporarily occluding it. However, by the time of the angiogram it had embolized distally, and had only done so after the right sided ECG was recorded.
See this case in which I saw STE in V1 and called the angiographer to suggest he look more closely at the angiogram. He did, found the true culprit, and went back in to stent it.
This is the ECG. You can listen to my explanation by playing the video.
1. To reliably diagnose RV MI, you need a right sided ECG.
2. In inferior MI, ST elevation in V1 is specific for RVMI. False negatives could be partly due to misleading angiograms!
3. In inferior MI, ST elevation in V1 is not sensitive for RVMI, and is particularly insensitive when there is ST depression (due to posterior MI) in V2.
4. ST depression in lead I is NOT useful in determining the presence of right ventricular MI
5. The condition of the coronary artery at the time of angiogram may be different than it was 30 minutes prior during recording of the ECG.