R.E.B.E.L. ECG of the Week #6

12 Dec
December 12, 2013

R.E.B.E.L. EM ECG of the Week #6The case from this week is from one of the PGY-1 residents at University of Texas Health Science Center at San Antonio (UTHSCSA).  Several of the details of the case have been changed to keep patient information confidential.

53 year old female with a past medical history of hypertension, hyperlipidemia, coronary artery disease, and 3 anterior myocardial infarctions s/p 4-vessel CABG (LIMA-LAD, RIMA-RCA, SVG-D1-OM1 sequentially) 9 months ago who presents with intermittent 10/10 chest pain that radiates to his left arm for the past 6 months. The chest pain is associated with nausea and shortness of breath but denies diaphoresis or syncope. Patient reports that the pain is the same as his index chest pain and is both exertional and non-exertional and will often wake him up from sleep. The pain can last 5-10 minutes and is always relieved by rest. The patient reports good medication compliance (on metoprolol, atorvastatin, enalapril, amlodipine, aspirin). He presented with similar symptoms 3 months ago but left against medical advice before a work-up could be performed. Now he presents with increasing frequency of chest pain.

BP 152/105  HR 86 RR 16 O2 sat 99% on RA   Temp 98.0

ECG from triage is shown…

Before reading on, try to come up with your own interpretation of this ECG before moving on to the final impression

Left Ventricular Aneurysm

  • Rate: Ventricular rate 62
  • Rhythm: sinus
  • Axis: Left Axis Deviation
  • QRS: Bifascicular Block (RBBB + LAFB)
  • ST/T Waves: ST-segment elevation in inferior leads (II, III, and aVF)
  • Final ECG Interpretation: Bifascicular Block with ST-segment elevation in the inferior leads (II, III, and aVF)

In this case we were able to get our hands on an old ECG performed 3 months prior (shown below):

Old ECG

ST-segment elevation usually reflects acute thrombotic coronary occlusion and the most effective treatment consists in early primary percutaneous coronary intervention (PCI) or by thrombolytic treatment. In patients that present with ST-segment elevation  and chest pain the differential diagnosis can include ventricular wall aneurysm/pseudoaneurysm, pericarditis, benign early repolarization (BER), and recurrent acute myocardial infarction. This places a great emphasis on emergency physicians and their competence and ability to interpret ECGs in a rapid, timely, knowledgeable manner.

LV aneurysm is uncommon and accounts for 3 – 4% of all patients with ST-segment elevation on ECG  (11992347).  Although uncommon, LV aneurysm (LVA) is not an infrequent cause of diagnostic error in activation of the cath lab. As a matter of fact, in a retrospective review, LVA was the most frequently misinterpreted ECG pattern in emergency department chest pain patients (11073474).  More than 80% of LVAs are anterolateral and are usually associated with total occlusion of the left anterior descending artery with inferior and posterior aneurysms being less common (11992347).

What are some ECG characteristics that would help differentiate STEMI from LVA?

  1. Patients with LVAs, will frequently also have significant Q waves in the same distribution as prior myocardial infarctions.
  2. A non-concave ST-segment elevation morphology has a sensitivity and specificity of 77% and 97% for acute myocardial infarction (11581081)
  3. Reciprocal changes on ECG is a frequent finding in the setting of acute myocardial infarction
  4. Acute myocardial infarction will have dynamic ECG changes, while LVA will often have static ECG changes making comparison to past ECGs a useful tool

Case Conclusion: Due to the new ECG changes patient was taken for cardiac catheterization which showed a 90% proximal SVG to RCA stenosis and an inferior/posterior ventricular aneurysm. It was thought that the ST-segment elevation in the inferior leads was due to the aneurysm (echo shown below).

Take Home Point:

  • In patients with chest pain and ST-segment elevation on ECG, it is important to distinguish between LVA and STEMI by looking at old ECGs to see if changes are old or new.

Post by:

Nicolas D. Spampinato, MD Nicolas D. Spampinato, MD

University of Texas Health Science Center at San Antonio (UTHSCSA)

PGY-1 Resident of Emergency Medicine

 Twitter: @nickspampinato

 

Bibliography

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Salim Rezaie

Emergency Physician at Greater San Antonio Emergency Physicians (GSEP)
Creator & Founder of R.E.B.E.L. EM

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1 reply
  1. Ken Grauer, MD says:

    NICE Case. (Note – I couldn’t open the Echo – as it said, “the video is private” – so you may want upload again and open for public viewing).

    I would add to the initial interpretation of the 1st ECG. It shows as you note sinus rhythm – bifascicular block (RBBB/LAHB) – and ST elevation in the inferior leads. Additional findings that are important to mention are: i) there looks to be 1st degree AV block (PR>0.22 sec) – which may be significant given the bifascicular block; ii) there probably was a prior inferior infarction (the initial r waves in II,III,aVF are tiny – and note esp. the notch in the downslope of the S in lead II – which is often a sign that prior infarction has taken place); iii) there is dramatic loss of R wave after lead V2 – consistent with prior large antero-lateral infarction; and iv) there possibly are either acute or recent ST-T wave changes on this tracing.

    Keep in mind that this is the ECG that was initially looked at BEFORE you had a chance to look at the prior tracing (from 3 months earlier) – so initial decision-making had to be made on the sole basis of THIS initial tracing. The history documents significant prior CAD/events + intermittent severe chest pain over the past 6 months – so consistent with a possible event at any time between now and the recent 6 months. Note in V2 that the J-point is down (about 3mm) – which is MORE than you would expect for simple RBBB (esp. since there is no more than minimal J-point ST dep in V1). Note also that there is ST coving and slight J-point ST dep in V3. This is NOT normal – and could reflect EITHER a recent or even relatively acute event. ST-T wave appearance in V4-V6 looks old. The inferior ST coving could be recent – though I’d guess old. Same for the flat ST dep in aVL. But given the history presented – one SHOULD entertain a possible recent or even acute even given ST-T wave appearance in V2,V3.

    The above exercise of course becomes EASY once the ECG from 3 months ago is obtained – since most of the above changes are new. But to my eye, there is NO WAY to know that the coved ST elevation in the inferior leads reflects LV aneurysm rather than recent infarction. This could have developed 3 months ago (and now be an aneurysm) – or it could have been due to an acute MI a week (or less) ago. Keep in mind also that the inf-post wall is a much less common site for LV aneurysm (as you mention).

    Again – NICE job Dr. Spampinato! – 🙂

    Reply

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