Chest Pain and RBBB. What do you think?

An elderly woman presented with 25 minutes of chest pain after working out.

This ECG was texted to me and I viewed it on my phone hurriedly during a meeting:

There was an old ECG with it:

What do you think?

The sender wrote: “I’m thinking proximal LAD or LM.  Your thoughts?”

I wrote: “Agree with cath lab activation.  STE V1 and new RBBB and LAFB.  But I’m only 50% certain on this.”

Let’s look at it again:

There is sinus rhythm with RBBB. 
There is also an rS in inferior leads, and qR in aVL, consistent with Left anterior fascicular block (LAFB).

The RBBB, however, does not have an rSR’, but simply a qR-wave (a very tiny r-wave which is less than 0.5 mm is analogous to a Q-wave).  RBBB in V1-V3 that begins with a Q-wave is a sign of MI, whether new or old.

There is also a bit of ST Elevation in V1.  In RBBB, the ST segment that comes after a large R’-wave in V1-V3 should have slight ST depression (in other words, the ST segment should be discordant to the R’-wave, similar to discordance in LBBB).

Leads V2 and V3 do show appropriate discordant ST depression.

RBBB generally has zero ST elevation anywhere, although there are occasional cases in which a small amount is present without pathology.

If you see STE in RBBB, you should suspect acute MI.

I have not seen an acute MI in the context of RBBB that had STE only in lead V1, which is why I was not entirely convinced by the ECG. 

Cath Result: Large Occlusion of Septal Perforator


Acute MI with new RBBB and LAFB is usually a very bad combination.  See these cases:

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