ECG Blog #430 — Just a Regular LBBB ECG?

The ECG in Figure-1 — was obtained from an older man who had just completed dialysis — and, is now complaining of abdominal discomfort that radiates to his chest.

• The consultant interpreted this tracing as “LBBB” (Left Bundle Branch Block) — but not indicative of anything acute.

QUESTIONS: 

• Do you agree with the consultant’s interpretation?
• How would YOU approach this case?

Figure-1: The initial ECG in today's case. (To improve visualization — I've digitized the original ECG using PMcardio). 

MY Initial Thoughts on Today’s CASE:

Given the older age of the patient in today’s case — and, the fact that he just completed dialysis — the chance of having underlying coronary disease is clearly increased. This patient's new complaint of pain that radiates to his chest therefore immediately places him in a “higher-prevalence” group for having an acute event (especially since hemodialysis is a procedure in which transient hypotension is not uncommon).

• For clarity in Figure-2 — I’ve labeled today’s initial ECG. The rhythm is sinus at ~85/minute (the RED arrow highlighing the upright P wave in lead II). The QRS complex is wide — with a morphology most consistent with LBBB ( = predominantly upright in left-sided leads I and aVL — and predominantly negative in the anterior leads).
• Serum K+ was normal. 
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• NOTE: By my observation over the years — the experts do not agree on the classification of LBBB vs IVCD (IntraVentricular Conduction Defect). As I review in ECG Blog #204 — “typical” LBBB is characterized by a supraventricular rhythm with QRS widening, in which there is a monophasic R wave in left-sided leads I and V6 — and an all-negative (or almost all negative) QRS in right-sided lead V1. 
• The above said — many patients with LBBB also have marked LVH. Given the leftward and posterior orientation of a markedly enlarged LV (Left Ventricle) — the presence of an all-upright R wave may not be seen in left-sided lead V6. Instead, the all-positive R wave with LBBB may sometimes only appear in more lateral and posteriorly-oriented chest leads, such as V7,V8 or V9.
• As a result — I would accept either LBBB or IVCD as a “correct” classification of the widened QRS morphology seen in Figure-2. Personally, I favor LBBB in view of the suggestive appearance of LBBB in the limb leads, with fairly deep anterior S waves — but my comments below are consistent with either LBBB or IVCD.

PEARL #1: Regardless of whether you interpreted the widened QRS morphology in today’s ECG as “LBBB” or “IVCD” — there are a number of ECG findings of increased concern beyond that of the conduction defect. Among them: 

• There should never normally be a Q wave in a lateral lead with simple LBBB. As discussed in ECG Blog #204 — this is because by definition, the conduction defect with LBBB prevents normal left-to-right septal depolarization. The same is true for an IVCD pattern that mimics LBBB in the limb leads (as is seen in today’s ECG). Therefore — the Q waves in Figure-2 (BLUE arrows in leads I and aVL) suggest that in addition to the conduction defect — there is also “scar” (usually from infarction at some point in time).

In addition to the abnormal Q waves — ST-T wave morphology is distinctly abnormal in almost every lead!

• While more difficult to assess because of the lack of an all-upright R wave in lateral lead V6 — the shape of the ST-T waves in multiple leads is just not normal.
• BLUE lines in leads V2,V3 show abnormal ST segment straightening (instead of the expected upsloping ST segment in these leads).
• PURPLE lines in leads V4,V5,V6 show abnormal downsloping ST segments (with marked abnormal ST depression in leads V5,V6). In addition — the biphasic T wave with marked terminal positivity in leads V5,V6 looks distinctly acute (ie, T waves are not normally upright in lateral chest leads with LBBB).
• Similar downsloping with marked, abnormal ST depression and abnormal biphasic T wave with marked terminal positivity — is seen in lead II.
• While ST segments in leads III and aVF are not nearly as depressed or downsloping (as they are in lead II) — the ST segment straightening that we see in leads III and aVF, with marked angulation at the point where the ST segment meet the beginning of the T wave — is clearly not normal.
• Finally — note how marked the ST elevation is in lead aVR (within the RED box in this lead).

Putting It All Together:

The older man in today’s case was clearly in a higher-prevalence group for an acute event — even before we looked at his initial ECG. As a result — there was need to assume that any potentially abnormal ECG findings that might be seen are acute until proven otherwise.

• In summary, the ECG in Figure-2 shows sinus rhythm with LBBB — and diffusely abnormal ST-T wave depression with ST elevation in lead aVR. At the least — this pattern is consistent with DSI (Diffuse Subendocardial Ischemia — See ECG Blog #271 for more on DSI).
• More than this — the Q waves in leads I and aVL — and the acute appearance of the downsloping ST depression with terminal T wave positivity — might reflect multi-vessel disease with recent and/or ongoing acute infarction.
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• Finding a prior tracing on this patient would be extremely helpful — as it would tell us what is "new" vs old.
• Obtaining serial ECGs should prove insightful. Especially when correlated to the presence and relative severity of symptoms — serial tracings will convey if acute injury is ongoing. For example — a reduction in symptoms in association with improvement in ST-T wave changes, would suggest that the "culprit" vessel is spontaneously opening!
• PEARL #2: In patients with ongoing symptoms — ST-T wave elevation and reciprocal ST depression may evolve over a period of minutes. As a result — Consider a repeat ECG as often as every 10-to-20 minutes in a patient with ongoing CP (Chest Pain) — until a definitive diagnosis can be made.
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• BOTTOM Line: On seeing today's ECG — prompt cath was clearly indicated.

Figure-2: I've labeled the initial ECG in today's case. 

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Acknowledgment: My appreciation to Mayan Kain (from Tel Aviv, Israel) for the case and this tracing.

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Related ECG Blog Posts to Today’s Case:

• ECG Blog #205 — Reviews my Systematic Approach to 12-lead ECG Interpretation.
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• ECG Blog #193 — Reviews the basics for predicting the "culprit" artery (as well as reviewing why the term "STEMI" — should be replaced by "OMI" = Occlusion-based MI).

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• CLICK HERE — for my 6 new ECG Videos (on Rhythm interpretation — 12-lead interpretation with Case Studies for ECG diagnosis of acute OMI).
• CLICK HERE — for my 2 new ECG Podcasts (on ECG & Rhythm interpretation Errors — and — Errors in assessing for acute OMI).

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• Recognizing hyperacute T waves — patterns of leads — an OMI (though not a STEMI) — See My Comment at the bottom of the page in the November 8, 2020 post on Dr. Smith's ECG Blog.
• Recognizing ECG signs of Precordial Swirl (from acute OMI of LAD Septal Perforators) — See My Comment at the bottom of the page in the March 22, 2024 post on Dr. Smith's ECG Blog. 
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• ECG Blog #294 — Reviews how to tell IF the "culprit" artery has reperfused.
• ECG Blog #230 — Reviews how to compare serial ECGs. 
• ECG Blog #115 — Shows how dramatic ST-T changes can occur in as short as an 8-minute period.
• ECG Blog #268 — Shows an example of reperfusion T waves.
• ECG Blog #400 — Reviews the concept of "dynamic" ST-T wave changes.
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• ECG Blog #337 — A "NSTEMI" that was really an ongoing OMI of uncertain duration (presenting with inferior lead reperfusion T waves).
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• ECG Blog #282 and ECG Blog #204 — review a user-friendly approach to the ECG diagnosis of the Bundle Branch Blocks (RBBB, LBBB and IVCD).
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• ECG Blog #203 — reviews ECG diagnosis of Axis, Hemiblocks and Bifascicular Blocks.