Anterior ischemia or posterior STEMI?

I know someone who recently came across an interesting 12 lead ECG on the Lifenet Receiving Station at their receiving hospital.

First I'm going to show it to you without the computerized interpretation.

Let us assume for the sake of discussion that this was a chest pain patient. Do you see anything that concerns you?

Now let's look at the same ECG with the interpretive statement.

Now what do you think? If this doesn't at least slightly improve your opinion of the GE-Marquette 12SL interpretive algorithm, it probably should!

Having only seen isolated acute posterior STEMI in textbooks, the paramedic in question printed out a copy of the ECG and brought it to the on-duty ED physician to find out the details.

He said, "Sorry, I just got on duty." The ECG had been transmitted to the Lifenet Receiving Station several hours earlier.

The paramedic in question happened to see a cardiologist that he know very well in the ED. He showed the ECG to the cardiologist and asked if he knew anything about the case. The cardiologist said, "Hey! Look at that!"

The paramedic in question said, "Yeah, I know. It's really interesting. Did this patient go to the cath lab?"

The cardiologist said, "Hmm. I don't remember hearing a Code STEMI."

The paramedic in question said [in jest], "I hope he's not still sitting around in the ED."

The cardiologist said [in jest], "Naaaah, that's pretty obvious.... even for an emergency physician!"

Both laughed.

Finally, the paramedic in question found the nurse who had taken care of the patient. She indicated that the patient had been admitted to the ICU.

Seeing the look on the paramedic's face, she asked what was on his mind. He said, "Well.... it's really none of my business...."

The nurse said, "Quality patient care is all of our business!"

The paramedic said, "Well, this looks to me like an acute posterior STEMI. I would have thought the patient would go to the cath lab."

The nurse said, "Let's look at the physician's ECG interpretation....." She clicked away on the computer. "ST-segment depression in the right precordial leads. Possible anterior ischemia."

The paramedic asked, "May I please know whether or not the cardiac biomarkers were positive or negative?"

She said, "First round was negative."

The paramedic in question followed up on the case. Turns out the second and third rounds were not negative.

CE #2: CKMB 20.05, CPK 213, Troponin 0.117
CE #3: CKMB 54.02, CPK 522, Troponin 0.288

Cardiac cath: 2-vessel obstructive CAD of 1st obtuse marginal and branch diagonal disease [sic]; 2 drug-eluding stents placed.

Discharge diagnosis: Non-ST segment elevation myocardial infarction

What lessons can be gleaned from this case?

*** Clinical pearl ***

Sometimes it helps to "flip" the ECG and hold it up to a light. It ends up looking something like this:

Can you see the STEMI now?

You can also consider using modified leads V7, V8, and V9.

Image from:

ABC of clinical electrocardiography - Acute myocardial infarction - Part 1

Electrode positions: V7: posterior axillary line, lead V8: midscapular, V9: paraspinal

See also: Pure (Isolated) Posterior STEMI - Not so rare, but often ignored!


Adam Thompson, EMT-P said...

That paramedics can & should speak up. Also, I am impressed with the ECG interpretation. I'm surprised an ED physician would look so lightly upon an ECG that diagnosed AMI. They are more likely to over diagnose an AMI than underdiagnose one, but I think a good second look at the ECG is necessary. This could have saved the patient some myocardium.

Good post!!

Tom B said...

I couldn't help but wonder if the ED physician in question even looked at the PH12ECG, or whether the PH12ECG ever found its way into the patient's chart.

Maybe the 12 lead ECG captured in the emergency department showed a different interpretive statement. It's hard to say.

What I found most interesting was the discharge diagnosis of NSTEMI. Have you ever wondered why, if the heart has 3 main vessels, that the vast majority of STEMIs are documented in the RCA and LAD?


Adam Thompson, EMT-P said...

The lack of posterior STEMI recognition & diagnosis?

Tom B said...

Yes, combined with the fact that the standard 12 lead ECG does a relatively poor job examining the distribution of the circumflex artery (which is almost saying the same thing).


Rogue Medic said...

Tom B,

Nice example. The software can make mistakes, but we should not ignore what it tells us.

I had an obvious V Tach, gave lidocaine, then ran the 12 lead. It stated that the rhythm was Atrial Flutter. I looked at it again. Still textbook VT. I was not going to give any calcium channel blocker, because I like to leave some cardiac conduction. I find it comes in handy. :-)

I notified command, we arrived and the cardiologist was already in the ED. The cardiologist looked at the 12 lead and stated that it looked like VT. They ran their own 12 lead, because they have the same 12-lead software, and you know that it will just work that much better on hospital equipment, than on EMS equipment. :-)

Their 12 lead showed A Flutter, too.

The machine may throw something odd at us, but we should not ignore it, even though it appears to be ridiculous.

The patient was awake and alert, with signs of good perfusion, so no further treatment was provided en route. In the ED they gave amiodarone, then cardioverted after some very healthy sedation.

Rogue Medic said...

Tom B,

I like the suggestion of flipping the 12 lead over and holding it up to the light, so that you are looking at it upside down and still seeing the P waves first, then the QRS, then the T waves. This can make it much more clear that there is some form of T wave inversion.