Pay Attention to aVR

AVR is not a diagnostic lead. Or so I have been telling people for many years because that is what I was taught. Then the other day I was at a cardiology CME, where a cardiologist was showing us various strips and he showed one that had ST elevation in AVR and widespread ST depression in other leads. Both he and the other cardiologist were in agreement that this was a bad sign. They called the ECG reading a “Left Main Equivalent.”

They said that ST segment elevation in AVR is a significant predictor of mortality in the setting of an MI. AVR lacks a contiguous lead, but as I understand it now, it is reciprocal to leads V4, V5, V6, as well as leads I and II. It provides a view of the endocardial area of the left ventricle and the apex as well as the base of the septum. ST elevation in AVR can be indicative of an occlusion of the Left Main Coronary Artery and/or significant three vessel disease.

In other words, patients presenting with possible ACS who have ST elevation in AVR should be treated very seriously.

Interesting.

What I love best about being a paramedic is not only learning new things, but then applying those lessons to my patients in the field.

Check out this ECG of a patient with chest pain:

The patient had extensive three vessel disease including a near 100% occlusion of the LAD and ended up requiring a triple bypass to restore adequate perfusion.

Here is some more information on AVR:

Lead aVR: Importance of the “Forgotten 12th Lead” in Patients With ACS

Don’t Forget Lead aVR…

Note: An check out the excellent comments below by Christopher that detail more uses of aVR.

3 Comments

  • Christopher says:

    (WordPress ate my first and second attempts)

    As you may have guessed, aVR is a wonderful lead for more than just LMCA/3-vessel disease!

    Perhaps the most basic usage of aVR should be as a 12-Lead gut-check. The P-wave and QRS complex should both be negative in this lead (somewhat of a simplification), or better stated: they should point away from aVR.

    Next on the list is VT rule-in for wide complex tachycardias. An initial positive deflection in aVR is pretty specific for VT. (But we were already treating wide and fast as VT, right?)

    Continuing, a fat slurred R’ or r’ in aVR in the setting of an ALOC patient should point you towards a significant TCA or Na-channel blocker overdose.

    And the last one I’ll touch on here is you can use PR-elevation and ST-depression in aVR as another sign of pericarditis. It isn’t the best of discriminators, but it puts another mark in the pericarditis column if present.

    My thought is aVR was the underdog in EMS due to the nature of the introduction of 12-Lead ECG’s: identification of STEMI. It wasn’t until relatively recently in the MD world that the usefulness of aVR was recognized in STEMI et al. Hence, most EMS education will leave out mentioning it (or worse telling you it has “no meaning”).

  • as always, more than a little excellently well stated chris…always a pleasure to read your commentary…clear. concise. coherent. clinically relevant. elegant and informative.

  • Chris P says:

    Great post, thank you !

    I’d like to add, if your see STE in aVR, don’t forget to check out aVL.

    STE in both aVR & aVL = very specific for LMCA stenosis !!

    Chris.

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Peter Canning

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