This case was sent to me by Taylor Sanders of the LSU- Baton Rouge Emergency Medicine residency.
A 29 year old complained of 6 hours of pleuritic chest pain:
QRS: There is rSR' in V1, consistent with RV conduction delay, but the QRS does not appear prolonged and there are no S-waves in lateral leads. However, this absence of lateral S-wave may be due to terminal QRS distortion from the ST Elevation.
A 29 year old complained of 6 hours of pleuritic chest pain:
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R-waves in Lateral leads: the R-waves in I and aVL are minimal, but are well formed in V5 and V6; this is somewhat unusual, and one must entertain the possibility of reversed limb lead placement. However, when the axis is 90 degrees, because V5 and V6 are inferior to limb leads I and aVL, they may show R-waves when I and aVL do not.
PR segments: there appears to be some PR depression in leads II and V3. In lead II, it is partly due to a downsloping baseline. This PR depression is suggestive of myo-pericarditis, but may also be found in MI. PR depression of greater than 0.8 mm is generally considered specific for pericarditis, but the data upon which this is established comes from the pre-angiogram era, and cannot be fully trusted.
ST segments:
There is marked ST elevation in inferior and lateral leads. Inferolateral STEMI and pericarditis are very difficult to distinguish, and the best means to do so is that with inferolateral STEMI there is virtually always ST depression in aVL, even when there is ST elevation in V5 and V6. There is no reciprocal ST depression in aVL and this makes inferior STEMI, even with superimposed lateral STEMI, very unlikely.
The ST axis in pericarditis is rarely to the right of lead II. An ST axis towards lead II results in no limb lead ST depression except in aVR (which is the opposite of a lead midway between I and II)
The ST axis in inferior STEMI is almost always to the right of lead II (resulting in ST depression in aVL)
ST depression in aVR is found in all etiologies of inferior ST elevation: pericarditis, early repol and MI. So this is not helpful. However, there is ST depression in V1 and V2: is this posterior injury? Or are these ST segments simply discordant to the R' wave, and a result of the abnormal depolarization ("secondary", not "primary" ST segment abnormalities)? In general, myo-pericarditis does not have reciprocal ST depression anywhere except lead aVR, but this may be an exception due to the R' waves in V1 and V2.
T-waves: These are prominent, and worrisome for MI or early repolarization. Early repolarization is possible, but less likely when not also seen in anterior leads. Slow upstroke and fast downstroke, and relatively short QT favor a non-MI diagnosis as well. T-waves in II, III, aVF and V4-V6 are very tall relative to the R-wave and QRS.
QTc interval: I do not have the computerized QTc for this case, but my visual inspection puts it at no longer than 380 ms. In our as yet unplublished study of inferior STEMI, only 7% had a QTc less than or equal to 380ms.
I was shown this ECG with just the clinical information above. I responded that this is probably myo- or peri-carditis but that I was worried about the size of the T-waves. And I often say the "you diagnose pericarditis at your peril." The fact that the pain was pleuritic and the patient was 29 years old is supportive of pericarditis, but look at this case of a 24 year old woman with chest pain after a night of drinking and vomiting.
The first troponin I returned at 6 ng/mL (significantly elevated).
Another ECG was recorded:
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| Now there is much more ST elevation in lateral precordial leads. There is also STE in aVL. (ST axis is to the left of lead II; this is highly suggestive of pericarditis. But how much do you want to bet?) |
A very reasonable course of action would be a formal echocardiogram to look for wall motion abnormalities. Absence of WMA would make STEMI impossible and establish the diagnosis of pericarditis without subjecting the patient to an angiogram.
It is also very reasonable to avoid any delay and go directly to the cath lab.
All coronary arteries were clean.
Final diagnosis: Myocarditis
Are those subtle u waves in the first strip? Due to electrolytes or can that be associated with myocarditis?
ReplyDeleteThey are U-waves, but they are normal U-waves. Not more prominent than they should be.
DeleteDr. Smith,
ReplyDeleteThanks for posting this very interesting case! You recommended comparing this case to the case of the 24 year old woman with AMI due to type III LAD STEMI. In that case there was no WMA even by an expert's formal echo, but you said in this case that absence of WMA would make STEMI impossible and justify avoiding the angiogram.
Could you please clarify why a lack of WMA would make you feel that cath was not necessary in this case but still necessary in the case of the 24 year old woman?
Judging from just these two cases, the presence/absence of ST depression in aVL seems to remain the best indicator. The 24 year old woman with STEMI had ST depression, while this 29 year old woman with myocarditis did not.
Haaa! Subtle distinction. What I said was a "formal echo" would rule it out. A formal echo is done with IV microbubble contrast (Definity brand) and high quality machine. The one on the 24 year old was a "bedside" echo, done with an inferior machine and no bubble contrast.
DeleteThanks!
DeleteThank you for this case. It seems that it was myocarditis with positive trop test. Coronary syndrome could appear in myocarditis. MRI could help very much in myopericarditis. I am interested in finding out more about both etiology and treatment.
ReplyDeleteGREAT case Steve! I love your step-by-step decision-making process on this case - and your phrase, "You diagnose pericarditis at your peril". Ultimately - there were unanswered questions deserving of cath - with important lesson that positive troponins + this series of ECGs + clean coronaries = acute myocarditis (a diagnosis that is often not made). THANK YOU - :)
ReplyDeleteIt's difficult to assess on this ECG, given the size and quality of the image, but do you think the p waves in V2 are inverted? Of course, this might suggest that the rSR' is due to superior lead misplacement.
ReplyDeleteGood observation. That could be. Steve.
DeleteDid a diagnosis of PE cross your mind pre-Echocardiogram? There is intra-ventricular conduction delay (rSr), right axis deviation and inverted t-waves anteriorly which are all associated with PE. Positive troponin wouldnt be unexpected but I appreciate the Echo may have yielded some clues....
ReplyDeleteI wasn't there, but I probably wouldn't have given PE a lot of consideration: no SOB, too much ST elevation, no tachycardia, too many causes of right ventricular conduction delay. But it is possible and certainly worth checking a d dimer.
DeleteWould echo alone differentiate between stemi and myocarditis? Although myocarditis can give regional wall motion abnormality as well. .. in either case coronary angio is the final path !
ReplyDeleteBut if there is no wall motion abnormality, you have ruled out any major coronary occlusion.
DeleteDo the height of the R waves play into your decision in MI vs myo/pericarditis? The R waves just seem mighty tall for STEMI. Thanks for the case!
ReplyDeleteGreat question. I always look at ratios. Yes, the R-waves are tall, but the T-waves are also tall. There is a higher T/R ratio than normal. In other words, relative to the T-waves, the R-waves are not all that tall.
DeleteSir, great case. ST elevation in multiple leads both limb and chest associated with marked PR depression in leads II and III.
ReplyDeleteP wave inverted not only in V1 but also in V2. All these findings suggest atrial and ventricular epicardial injury. Sir, your comment.