EXTRA COPY — ECG Blog #551: Are there any "Normal" Beats? — EXTRA COPY

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I was sent the ECG in Figure-1 — told only that it was from a middle-aged man who presented for acute CP (Chest Pain).  

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

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Figure-2: XXXX

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Acknowledgment: My appreciation for the anonymous contribution of today's case. 

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mohammad dalirian <mdalirian1380@gmail.com> (2/25/2026)

From: mohammad dalirian <mdalirian1380@gmail.com>

Subject: ECG - February 25, 2026 at 2:40:57 PM EST

Hello Professor - Do Anonymous 

Middle aged man with chest pain — What's the Rhythm & Culprit?

MY REPLY:

— Are there “Normal” Beats? —

I was sent this tracing = Middle-aged man with CP — How to approach?

Hi. This is a VERY challenging tracing!

• Is this YOUR patient? OR — Did you find this case on the internet? If on the internet — please give me the exact LINK to where it was posted.
• If you could get me some follow-up as to what happened? Perhaps a follow-up ECG? If cardiac cath was done — or  if thrombolytics were given — then I’d LOVE to do an ECG Blog on this case IF you would give me permission?

• As you can see in the long lead II rhythm strip — QRS morphology continually changes! But the underlying atrial rhythm is regular! (RED arrows).
• Beats #1,3,4,6,8,11,13,15 are all sinus-conducted beats. 
• The other beats are PVCs. Those PVCs with a P wave in front of them ( = beats #2,5,9,12,) are FUSION beats ( = the on-time sinus P wave was able to partially conduct until it encountered the ventricular beats. 
• Note that there is a ventricular couplet (2 PVCs in a row) for beats #9,10. The distance between these 2 beats = 2.6 large boxes, which corresponds to a ventricular rate of ~115/minute, which is slower than the rate for VT (Ventricular Tachycardia). Therefore — rather than VT — this is AIVR (an Accelerated IdioVentricular Rhythm) — and AIVR in the setting of an acute MI is often a “reperfusion” arrhythmia. I don’t know WHEN this ECG occurred with respect to the onset and duration of this patient’s CP ???? But reperfusion ( = reopening) of the acutely occluded coronary artery, which we call the “culprit” artery — can occur following cath with PCI — or — following thrombolytics — or — occur spontaneously. In any case — if this is a reperfusion arrhythmia, then the patient’s CP shoud have decreased!
• Note that the PVCs change the QRST morphology! — so it’s best to look at the sinus-conducted beats in each of the 12 leads to assess for ST-T wave changes. Within the dotted BLUE rectangles, are sinus-conducted beats in each of the 12 leads!
• In leads I,II,III (ie, for beats #1,2,3,4) — there is a large Q, ST coving and shallow T wave inversion for sinus-conducted beats #3,4. There is ST depression in leads I and II.
• In leads aVR,L,F (ie, for beats #5,6,7,8) — the ST segment of beat #6 looks a bit elevated (if not altered by some artifact). There is reciprocal ST dep in lead aVL for beat #6 — so I think there has been an inferior MI at some point in time. But it is hard to determine the acuity of this without knowing specific details about the history ( = When did CP begin with respect to this tracing? Was the patient still having CP at the time this ECG was recorded? Is there any prior history of a previous MI?
• In the chest leads — beat #11 is sinus-conducted — and it shows ST elevation in leads V1,V2,V3 (with the most ST elevation in lead V3 !!!!)
• In leads V4,V5,V6 for beat #13 — there is ST flattening and dep in leads V5,V6.

BOTTOM LINE — My guess is that this ECG represents an acute STEMI from proximal LAD occlusion (producing a “Precordial Swirl” pattern in the chest leads = See ECG Blog #380 — for more on Precordial “Swirl”). The evidence of inferior MI could either be acute (from an LAD with “wraparound” that also supplies the inferor wall) — or more likely from a prior inferior MI. History, prior tracings, cath results etc would be needed figure this out ...

 

So — What happened? I hope the above is helpful — :) Ken