EXTRA COPY — ECG Blog #538 — An Unusual Finding — EXTRA COPY

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

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Figure-2: XXXX

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Figure-3: XXXX

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Figure-5: XXXX

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With this laddergram — YELLOW arrows are retrograde P waves. Although subtle, the RP' interval is increasing (most easily appreciation by looking at the RP' interval before the retrograde Wenckebach conduction is blocked (darker BLUE double arrows). Note subtle increase in the angle of retrograde p waves that are maximal just before the P wave is dropped (BLUE lines in AV Nodal Tier) — and then the RP' interval shorts again beginning with beat #13.

I must cite the following as PROOF that retrograde Wenckebach confirms VT (with exception of Junctional tach with wide QRS)

— Roig et al — Circulation 153:1171-1173, 2026

https://www.ahajournals.org/doi/epub/10.1161/CIRCULATIONAHA.126.080138

AWAIT Khaled to confirm acknowledgment

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Acknowledgment: My appreciation to Khaled Elashiq, Hasan Al-Qassim and Mahmoud Al-Rahmoun (from Syria) for contributing this case.

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Case from Khaled Ash from Damascus Syria

— "An unusual finding ..." —

— NOTE — This was a very complex case, but I will only give a brief 1-line history — saying this is a young adult complaining of frequent palpitations

— The Dx is Fascicular VT (NOT RBBB aberrancy given atypical features)

— Me to ask, "How certain are you of the diagnosis? HINT: Is there atrial activity? If so — Is there something unusual about atrial activity?"

— Quote article — Retrograde Wenckebach in the setting of a persistently regular WCT is very strongly suggestive of VT (even more so than AV dissociation) — since if the rhythm was supraventricular, it would change the R-R interval!

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Hard to believe this patient was markedly hypothyroid!

That said — I want to make an ECG Blog of this case — and I've spent a few hours fixing up the tracing, since the original was rotated and missing a complex in lead V3. I'll add a laddergram.

It is RARE to see VT with retrograde Wenckebach like this — and as per the attached article, seeing this is diagnostic for VT (with the very rare exception that you could theoretically see retrograde Wenckebach in junctional tach with a wide QRS from BBB).

I'm happy to acknowledge both you and your colleague from who this case comes. That said — I don't feel obligation to necessarily acknowledge your colleage — since I have totally redone the tracing (attached) using PMcardio, and since I will NOT be using clinical details of the case (I'll only give a VERY simple 1-line history). I am HAPPY to acknowledge you if you like (Khaled Ash — from Damascus, Syria) — or I could make the case anonymous, as you prefer.

I've done lots of Fascicular VT cases — so the main reason for doing an ECG Blog is the rare example of retrograde Wenckebach that essentially PROVES this is VT (I suspect many readers won't know what to do with the concept of retrograde Wenckebach.

It will be a while before I publish this — but in any case, I'll let you know when I do. Just LET ME KNOW what you prefer. THANKS — :)