Need Help with an EKG

[K.N.]

Hello there. Going to risk poor form here and be asking a homework question in my first post. If it makes it any better the assignment is basically over, and I’m looking for a better understanding of the problem.

It’s a problem based learning question, a 55 year old obese man experiences syncope while driving. He is given a Holter Monitor for 24 hours that reveals an intermittent AV block. He is given a pacemaker. One year later, he experiences dyspnea, chest pain and dizziness, again while driving. My main question revolves around the 12-lead EKG he receives at this point.

We were sent home after this and I personally believe there is:
-widespread ST depression
-left axis shift
-aVF inversion

I combined this with his symptoms and guessed that it is an inferior wall infarction.

As you can guess I was incorrect, the answer was revealed to be a complete occlusion of the proximal LCX, which if I’m not mistaken, leads to lateral wall infarction.

I’ve spent quite a bit of time looking for a way to see this in the EKG, but I’m just not getting it. If this patient has a lateral wall infarction, wouldn’t there be a larger Q-wave? A right-axis shift instead of a left-axis shift because of the now-weaker current from the lateral wall? ST elevation in LV leads and reciprocal depression in the opposite ones?

Furthermore, is this considered a STEMI, or NSTEMI? I spot no ST elevation in the EKG, but the text for the problem states that his artery is completely occluded, so treating it like an NSTEMI would be bad, would it not?

For the record our class has only had 2 hours of actual EKG lectures (although there’s a bit peppered throughout other classes), so I’m sure I’m missing something really obvious here.

Would appreciate any help.

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[CrimsonKing]

Unless this guy had positive troponins, there is no current evidence of infarction. This guy may have total occlusion of the proximal LCX. The diffuse ST depression can simply be indicative of ischemia w/o infarction and is not localizable. There is no >1mm ST elevation to suggest a localized acute infarct.

In regards to past infarctions, there is a Q wave in III, but not in II or AVf, making an old inferior infarct less likely. However, there is an S in I, meaning this EKG may have the classic Q1S3 pattern suggestive of a LBB posterior fascicuar hemiblock, which could result from a small area of infarction secondary to LCX occlusion.

 

[K.N.]

Sorry, forgot to mention that he does have positive troponins, and we were straight told he had total occlusion of the proximal LCX at the end.

Since there is no ST elevation, does that mean fibrinolytics would be a bad idea? (We were told the patient was given PTCA + stent)

I see the S in I but don't believe there's an Q in III. If this was a posterior fascicular hemiblock, wouldn't it also have a right axis shift? I keep seeing a left axis shift in it which is what keeps throwing me off.

Thanks.

 

[Microshaft]

I could be wrong but NSTEMI makes sense because of +ve TnI, widespread ST depression

also total occlusion of an artery doesn't automatically mean infarction. it can be asymptomatic as in the case of CTO

i dont believe streptokinase is indicated in NSTEMI.

also why is the ECG in chinese

 

[K.N.]

In this particular case it seems the patient did have an infarction resulting from the occlusion, so I'm still a bit confused what caused the left axis shift. Thanks for that info, though.

The Chinese is because its a Chinese School. It just says Figure 2.

 

[Fluffy Pomeranian]

Maybe I'm wrong but I'm pretty sure this is a normal axis, not a left axis deviation.

 

[TooMuchResearch]

Are you sure the answer was left circumflex and not left main coronary artery (LMCA)?

LMCA occlusion is bad news.

Look at this ECG again. There is diffuse ST depression notable in the lateral leads as well as significant ST elevation in aVR. aVR is often neglected but is very important.

Here is a link to a quick review of LMCA ECG findings:

http://lifeinthefastlane.com/ecg-library/lmca/

 

[Jabbed]

Small corrections:
1) LCX occlusion can cause an IWMI in a left dominant system.
2) I don't see the LAD. It looks like -10 degrees if that. What criteria are you using?
3) aVF changes are pretty non-specific.
4) This is an NSTEMI. NSTEMI's will still be catheterized within 24 hours. Check UpToDate for the relevant treatments for STEMI vs NSTEMI.
5) You can have an MI without a Q wave.

Looking at this without a prior EKG, I would read: sinus tach with diffuse ST depressions and T wave inversions c/w ischemia. Possible LMCA vs LCX occlusion.

The ST depressions in the left lateral leads are borderline nasty and should make you think LCX over RCA occlusion. Honestly though I would be most worried about a LMCA occlusion based on the aVR elevation and diffuse ST/T wave changes. The only factors going for LCX over LMCA are 1) flat ST in V1 and 2) LCX occlusions are far more uncommon than LMCAs.

Do you know what the historical intermittent AV block was?

 

[Jabbed]

Also beware of diagnosing prior infarction based on Q waves solely in lead III specifically. They very often occur in patients with horizontal hearts (ie obesity). Lead aVF is actually an averaged signal of leads II and III. Unless the Qs extend from III to aVF I would be very hesitant to call it an infarction without a compelling hx or supporting findings.

 

[K.N.]

Here is a link to a quick review of LMCA ECG findings:

http://lifeinthefastlane.com/ecg-library/lmca/

The given answer was proximal LCX, but its completely possible we were given the wrong answer, or I guess we were supposed to consider LMCA because they mentioned "proximal" LCX? Amazing how that looks like its the exact same EKG. Guess the professor just "borrowed" that one.

Do you know what the historical intermittent AV block was?

We were given parts of the Holter Monitor EKG, and it showed both second degree (type1) and complete heart block.

Thanks a lot for all your replies, I've learned a lot!

 

[Jabbed]

We were given parts of the Holter Monitor EKG, and it showed both second degree (type1) and complete heart block.

AV node is supplied by RCA and LAD. Ischemia isn't the only cause of AV block, but a history of intermittent 3rd degree and this EKG would make me VERY suspicious for LMCA occlusion. Even though strict STEMI guidelines aren't met (in this case there is no contiguous ST elevation from aVR to V1), I would activate the STEMI protocols.

 

[Priapism4tooLong]

The given answer was proximal LCX, but its completely possible we were given the wrong answer, or I guess we were supposed to consider LMCA because they mentioned "proximal" LCX? Amazing how that looks like its the exact same EKG. Guess the professor just "borrowed" that one.



We were given parts of the Holter Monitor EKG, and it showed both second degree (type1) and complete heart block.

Thanks a lot for all your replies, I've learned a lot!

This is a typical LMCA ecg. I don't know how you could come up with LCX? especially proximal LCX, which i guess could present similarly.. thats just getting too nitty gritty

 

[TooMuchResearch]

This is a typical LMCA ecg. I don't know how you could come up with LCX? especially proximal LCX, which i guess could present similarly.. thats just getting too nitty gritty

Yeah, if it looks like LMCA, I would call it LMCA, even if some chance of LCX exists. OP, don't screw around with the LMCA.

Also, I didn't learn to appreciate this pattern as a med student.