This is Part II of the conclusion to 80 year old male CC: Chest pain. For Part I see Excessive discordance as a marker of acute STEMI in LBBB.
First, let's take another look at the initial 12-lead ECG.
The first thing that catches my eye in this ECG is the strange morphology of the ST-segments and T-waves in the inferior leads (and lead aVL).
Could these be reciprocal changes to an acute anterior STEMI?
This ECG easily meets Sgarbossa's criterion of discordant ST-elevation > 5 mm, but is the ST-elevation excessively discordant when taking into account the depth of the S-wave?
Let's apply Dr. Smith's decision rule (that we learned about in the previous post). Do we see "excessive discordance" in this ECG?
Yes!
If this isn't evidence enough there are also significant changes in QRS voltage and ST/T morphology between the first and last 12-lead ECG.
Diagnosis: Acute anterior STEMI in the presence of LBBB.
See also:
80 year old male CC: Chest pain
Excessive discordance as a marker of acute STEMI in LBBB
Discordant ST-segment elevation in LBBB or paced rhythm
62 year old male CC: Chest pain
58 year old female CC: Chest pain
New left bundle branch block is a poor predictor of coronary occlusion (Dr. Smith's ECG Blog)
I guess I was most surprised that II/III/aVF/I/aVL were “discordant”. I’d always been looking for concordance with the terminal deflection. Perhaps a terminology change, “principle deflection”?
I don’t know, Christopher. The inferior leads in this case don’t follow the usual morphology for LBBB. Usually the “principle deflection” is the terminal deflection for LBBB (and of course you definitely use terminal deflection for RBBB). Dr. Smith (and others) use the main deflection when determining discordance or concordance. However, Tomas Garcia, M.D. uses terminal deflection and reportedly even asked Elena Sgarbossa, M.D. about it at a medical conference. In this case it wasn’t critical for the diagnosis, so I’m just going to make a mental note of the problem.
Tom
I didn’t get it well !! does it mean to maesure the ST/QRS ratio in all precordial leads or in specific leads to say at the end it’s STEMI in the presence of LBBB !! and is this correct even in the setting of Left ventricualr hypertrophy ?
The second point it is not true that STD in the inferior leads represent reciprocal to lateral STE until proven othrewise . Don’t you notice STE in aVL ?
PS ! the more deep S wave the more elevated ST segment this feature is not normal for LVH !! which is seen in this case .
Tom, I went back to Chou’s for some soul searching and found it describes it differently:
- In LBBB with a prominent R wave, you’re looking for a negative T wave
- In LBBB with a prominent S wave, you’re looking for a positive T wave
Chou’s does not remark on the terminal deflection in the section on LBBB.
I thought the changes from first to last ECG were very interesting and subtle. The only obvious red flag supporting MI, to me, is a slight (~1 box) fattening of the T waves.
I am aware of what Chou says. However, it’s not that simple, IMHO. I’ve seen too many cases where an Rs complex showed a positive T-wave in the setting of LBBB. Keep in mind, T-wave changes are non-specific. What really matters is the ST-segment. When you have an equiphasic QRS complex, or even one where the R-wave is taller than the S-wave is deep, in my experience the T-wave can be positive, flat, biphasic, or negative, but the ST-segment is isoelectric (or very close to isoelectric). I still think there’s a ST/T wave abnormality in the inferior leads for this case but you’d have to have an “old” ECG for comparison to appreciate it.
Tom
Take this ECG as an example:
http://www.medtees.com/blog/EKG14baseline.jpg
Would you call the relationship between the QRS complex and T-wave abnormal in lead V6?
Tom
IMO the example you give is clearer when you consider the context of V6; watching the S-wave progress through the other precordials makes it clear which deflection is the relevant one, despite the sudden appearance of that substantial R-wave.
Regarding the T-waves, can’t we just say that concordant T-waves are non-specific and not nearly as troubling as concordant ST changes — but are nevertheless somewhat suggestive of an ischemic event? If we limit our radar to only the most knock-down findings, we’d have to ignore an awful lot of the ECG!
You’re right, Brandon. In this context V6 is essentially a transition lead. I also agree we can say that concordant T-waves are nonspecific whereas concordant ST-segments are diagnostic. Provided of course that they are clearly concordant. Take lead aVL for example. It looks “wrong” because the T-wave is concordant with the terminal deflection but it’s discordant from the main deflection (unusual for LBBB). So what’s next? I fall back on Tomas Garcia M.D.’s advice. “Consider the company it keeps.”
Tom
Agreed. It’s good and right to try to “drill down” into every indicator we can, but life being what it is, many times the best we can do still leaves ambiguity. That’s the value of having a whole host of other findings to guide the way; it’s only when they’re ALL ambiguous that you’re in trouble
Tom, interesting ECG. I think I’d likely to ignore those sorts of changes in isolation, especially in V6. But what struck me in the original ECG was that all of the limb leads had such “odd” ST segments. I’m quite interested in this difference! Although from what I have read up, you’re on point that in LBBB the T wave changes can be almost any combination. If I had read a bit further in Chou’s it notes that if there is a dominant R in I/aVL/V5/V6 often times you have a positive T-wave without an ischemic origin. It also notes that the repolarization abnormalities may soften the amplitude which may visually produce these discontinuities. Considering the company it keeps, I often think of potassium problems when I see odd ECG morphologies with a block!
you guys over-analyze unnecessarily. you make so much hoopla over basic diagnosis lol.
especially TOM B. he says so much crap
You sound like a real Fulbright scholar, Malcolm X. Since identifying acute STEMI in the presence of LBBB is so “basic” maybe you could educate us so we can avoid all the hoopla (crap). Astonish us.
lol do what you do TOM B. get your grandiose on
seriously though TOM B i am just busting your chops. i am having a bad day as you can tell and i was hoping to transfer it to someone else. anyway so TOM, would you happen to have any material or video on holter analysis ? you think you can help me out here ?