Monday, October 4, 2021

A woman in her 60s with misdiagnosed palpitations, part 2: Case follow up!

 Written by Pendell Meyers

This post will be follow up information on the patient from this recent case linked below. Make sure to read that one first, then see what happened to this patient in this post below!

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

Here is the ECG:

Here is the explanation:

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.

In this case, however, the EM provider was worried for possible STEMI in the inferior leads, and the cardiology provider misdiagnosed the rhythm as atrial flutter, starting the patient on eliquis. Based on our ECG interpretation, neither of those is correct!

Case continued:

The patient was scheduled for electrophysiology follow up for her "new onset atrial flutter." So I looked up which provider she was scheduled to see, and I wrote that physician a message explaining my thoughts from the post above, explaining that I thought it wasn't atrial flutter, she likely doesn't need eliquis, and her actual dysrhythmia could likely be diagnosed and solved with an EP study. 

The electrophysiologist wrote me back and agreed.

The patient was then seen in follow up clinic by the electrophysiologist, and soon scheduled for an EP study.

Several days later she underwent the EP study. Ultimately, she had focal ectopic atrial tachycardia confirmed and successfully ablated, after which it was no longer inducible. Here are some relevant excerpts with much more detail for those interested:

"Patient had easily inducible and incessant atrial tachycardia that initially appeared to be the earliest in the proximal coronary sinus atrial electrograms in the proximal and distal representing the left atrium revealed late signals." 

"Atrial signals were obtained during atrial tachycardia throughout the right atrium. Earliest signals were noted both intracardiac and with 3-dimensional mapping with CARTO activation mapping to be at least 65 ms pre-earliest atrial activation which was the proximal coronary sinus. This was at the 6 o'clock tricuspid annulus."

"Following ablation, initial ablation within a few seconds the tachycardia terminated with no further atrial tachycardia....With infusion of dobutamine and waking patient up from sedation, no further atrial tachycardia was induced with singles and double extra stimuli as well as burst atrial pacing. Prior to ablation patient had easily inducible atrial tachycardia. After waiting approximately 30 minutes from the time of the successful ablation, no further PAC's or atrial tachycardia was noted."

"Impressions: Incessant focal atrial tachycardia arising from the posterior inferior tricuspid annulus (6 o'clock) status post successful ablation."

Eliquis was discontinued. Metoprolol was continued for now. 

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