Tuesday, September 21, 2021

A woman in her 60s with palpitations, chest discomfort, and multiple misdiagnoses by both EM and Cardiology!!

 Written by Pendell Meyers

A woman in her 60s was shopping when she suddenly experienced palpitations and chest "discomfort." She denied outright chest pain or dyspnea. She walked across to the street to my Emergency Department. She had no known prior history of dysrhythmias or heart disease, but had known hypertension, breast cancer, diabetes, and obesity. She has had episodes of palpitations in the past, followed by holter monitor workups which did not reveal any cause of palpitations. However, her symptoms today feel worse than prior episodes, and she has never felt the "chest discomfort" with prior palpitations. Upon pointed questioning, she told the providers she has had several similar episodes over the past few weeks, but did not seek care during those episodes and they were shorter.

Here is her triage ECG during active persistent symptoms:

What do you think?

We see a regular, narrow, monomorphic tachycardia, for which the full differential would include sinus tachycardia, SVT (an umbrella term including many different rhythms), and atrial flutter. 

This ECG has a large negative atrial wave just before the QRS complexes in the inferior leads, with only one of these waves visible for each QRS complex. These waves are of course fully upright in V1. The differential includes a low ectopic atrial tachycardia near the AV node, or a relatively high AVNRT such that the circuit activates the atrial retrogradely before the circuit can activate the ventricles anterogradely during each lap of the circuit.

It is not atrial flutter, because with such a prominent atrial wave seen in the inferior leads we should be able to see a second set of these waves midway between the visible ones.

Whatever the atrial waves are, their QRS complexes in the inferior leads are followed by ST segments which seem to be slightly above the baseline in III and aVF. Because I have been fooled by this phenomenon before, and because it does not match OMI patterns I've seen before, I can see that this morphology is likely due to the upright atrial repolarization wave from the dysrhythmia. If there were any question whether it were due to OMI, I would first convert the patient out of this dysrhythmia then reevaluate the ECG for OMI.

The Emergency Medicine team perceived inferior STE in II, III, and aVF, with slight reciprocal STD in aVL, and decided to activate the cath lab for chest discomfort and possible STEMI. Cardiology came immediately and deactivated the cath lab after looking at this ECG and believing that it represented atrial flutter with 2:1 block (this is almost certainly not atrial flutter). 

Approximately 20 minutes later it spontaneously converted to sinus rhythm:

2 hours later it recurred:

She was given 10 mg of diltiazem IV and had conversion back to sinus soon afterward.

Prior ECG on file:

Two high sensitivity troponin I measurements were less than 6 ng/L.

The cardiology team incorrectly diagnosed this rhythm as atrial flutter with 2:1 block.

She was admitted for rate control and "new onset atrial flutter workup."

Echo was normal.

Unfortunately, in the mindset of atrial flutter, the patients CHADS2VASc score was calculated at 3, and she was deemed to require anticoagulation with eliquis (apixaban), which she has been on ever since (several months at this point). I am trying to contact her providers to discuss this.

She was also placed on metoprolol, presumably for rate control during her perceived atrial flutter episodes. In reality, it may be suppressing her SVT (whether it is ectopic atrial tachycardia or AVNRT).

Check out these posts showing atrial repolarization (Ta wave) and how it can cause inferior pseudoSTEMI/OMI patterns:

A man in his sixties with chest pain

Look at this ST Depression (It's not real)

Atrial Repolarization wave mimicking ST Elevation:

Sudden CP and SOB with Inferior ST Elevation and in STE in V1. Is it inferior and RV OMI?

A man in his sixties with chest pain

Learning Points: 

Atrial repolarization can be especially visible in ectopic atrial tachycardias (or any dysrhythmia with pronounced ectopic atrial waves), causing the appearance of inferior STE that has nothing to do with OMI.

Diltiazem should not generally cause conversion of atrial flutter to sinus rhythm. Diltiazem converting the rhythm would be more consistent with a reentrant dysrhythmia involving the AV node, such as AVNRT. There is always a chance that the conversion was actually just spontaneous and not associated with the diltiazem.

Misdiagnosis of atrial flutter can lead to significant long term patient harm, especially when treated with anticoagulation. Sometimes getting the rhythm correct is very important. 

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