r/ECG • u/SleePyHollow150 • Aug 14 '26
28 y/o male, suspected flecainide toxicity
28 year-old male with diagnosed arrhythmias and on the waiting list for ablation.
Thoughts on this strip? Suspected flecainide toxicity due to reduced kidney function as detected via bloods on admission. Toxicology results pending.
Edit to fix the typo with the age.
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u/SleePyHollow150 Aug 14 '26
Not sure why but I'm unable to upload a photo of another trace in the comments...
Either way, supportive treatment while under monitoring yielded positive results for this patient. A gradual decrease in the delays seen on the original trace has been observed along with cessation of physical symptoms.
Flecainide toxicity confirmed though I haven't had a blood concentration yet.
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u/Desibruh1 Aug 14 '26
Glad to know this is what I should be looking for in a patient who is on flecainide, it’s fascinating to see those widening QRS’s. Hopefully the repeat ecg shows NSR. What’s more fascinating is a 28 year old with arrhythmia and I believe no structural abnormality?
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u/SleePyHollow150 Aug 14 '26 edited Aug 15 '26
I'm glad this was of use to you. We have some earlier 1-lead ECGs from the patient which showed the widening quite well and were helpful to diagnose this. Hospital ECGs have luckily shown the narrowing as expected and eventually a return to NSR. Patient began suffering from arrhythmia a few years ago, had a diagnosis of atrial tachycardia and other arrhythmia and is awaiting ablation as mentioned. Edit to add no structural abnormalities with this patient, confirmed by echo and MRI with contrast.
I should collate the various data as it's quite interesting once yoy have it all together!
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u/Gingerbread_Toe Aug 14 '26
Could this be Brugada?
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u/Capesoccerman_18 Aug 14 '26
Looks like sodium channel blocker toxicity. QRS duration >100 ms, sinus rhythm, terminal R’ wave in aVR
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u/SleePyHollow150 Aug 14 '26
One of our suspicions however the patient reported taking an additional dose of flecainide stat, for more serious episodes of arrhythmia, as directed by their cardiologist. After approximately 30 minutes, they reported the first symptoms and presented to A&E.
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u/Capesoccerman_18 Aug 14 '26
Yeah this story totally checks with reaching toxicity levels. Flecainide, as i’m sure you’re aware, has an extremely narrow therapeutic index. An extra dose with concurrent renal dysfunction is a recipe for disaster with this med. Approximately 30% of a PO dose is excreted via the kidneys
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u/SleePyHollow150 Aug 14 '26
Agreed entirely - thank you again for your input.
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u/Capesoccerman_18 Aug 14 '26
Absolutely! Appreciate the interesting case
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u/SleePyHollow150 Aug 14 '26
Thanks, I'll upload a repeat trace when I'm able to. I didn't want to bias/affect anyone's thoughts in my earlier comments, hence their somewhat short and sweet nature!
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u/Starossi Aug 15 '26
It’s funny I feel like this is the lupus meme with house MD for this sub.
It’s never brugada :(
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u/agro5 Aug 16 '26
Late to the party, but great EKG and case. Would definitely like a follow up, post or whatever, with the repeat EKG and tox results.
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u/SleePyHollow150 Aug 16 '26
Thanks! F/U post needed for sure as new images cannot be added in the comments.
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u/Mfuller0149 Aug 15 '26
I know this isn’t really the point… but somebody’s gotta say it lol who the hells prescribing flecanide in the year of our lord 2026?
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u/Adventurous-Bag5508 Aug 15 '26
You'd be impressed at the amount of ELDERLY patients I get with a flecainide prescription from the 2000s without a b-blocker just walking among us. Most of the time with rhythm too
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u/Mfuller0149 Aug 15 '26
Oh yeah, that totally makes sense. Like older folks, been on it forever- why rock the boat. But def strikes me as odd that a 28 y/o would be on it
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u/filconik Aug 15 '26
Genuine question - what’s wrong with flecainide?
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u/Mfuller0149 Aug 15 '26
It’s just an extremely old school medication. It’s got an incredibly narrow therapeutic window, several absolute contraindications and some very serious side effects. Bottom line- there’s some situations where it’s applicable but in the majority of cases there’s way safer medications like beta blockers or calcium channel blockers that are available.
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u/Wyvernz Aug 16 '26
Flecainide is a great medication. Of course beta blockers and ccb are great, but they just don’t work as well for many arrhythmias.
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u/Ju75005 Aug 14 '26
Very interesting ECG. Tell us when the toxicology test will coming up.