EM:RAP 2019 May - SNACK - The RACE Trial

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Steve D. -

Do you have evidence that A Fib begets more A Fib?

Gabe W. -

Al is no doubt an amazing EM physician and educator. In this case, I have to question whether he is trying to justify a procedure he has been doing for years despite now having evidence to the contrary. Al mentions that in EM we take action - we splint the ankle even though it will improve by itself. However there is minimal risk and cost to splinting an ankle.

It seems the cost of a sedation and procedure (cardioversion) may result in thousands of extra dollars of charges to a patient who has a 70% of not needed that 48 hours later.

Yes - certainly if the patient is quite symptomatic and it is disruptive to their life, the conversion should be a consideration. However, I've seen plenty of new A-fibbers who had minimal symptoms or didn't even realize they were in the rhythm.

Similarly, plenty of people have a lousy week with influenza and they tolerate the symptoms.

To analogize this differently similar to the splint or ankle sprain:

If a pneumonia patient had 70% of getting better in 48 hours with no antibiotics, I would likely withhold them pending a 48-hr follow up.

Alfred S. -

Steve: Here are some references for A-fib begets A-fib.

1: Lu Z, Scherlag BJ, Lin J, Niu G, Fung KM, Zhao L, Ghias M, Jackman WM, Lazzara
R, Jiang H, Po SS. Atrial fibrillation begets atrial fibrillation: autonomic
mechanism for atrial electrical remodeling induced by short-term rapid atrial
pacing. Circ Arrhythm Electrophysiol. 2008 Aug;1(3):184-92. doi:
10.1161/CIRCEP.108.784272. Epub 2008 Jun 23. PubMed PMID: 19808412; PubMed
Central PMCID: PMC2766842.

2: Zhang L, Po SS, Wang H, Scherlag BJ, Li H, Sun J, Lu Y, Ma Y, Hou Y. Autonomic
Remodeling: How Atrial Fibrillation Begets Atrial Fibrillation in the First 24
Hours. J Cardiovasc Pharmacol. 2015 Sep;66(3):307-15. doi:
10.1097/FJC.0000000000000281. PubMed PMID: 25970842.

3: Liżewska-Springer A, Dąbrowska-Kugacka A, Lewicka E, Królak T, Drelich Ł,
Kozłowski D, Raczak G. Echocardiographic assessment in patients with atrial
fibrillation (AF) and normal systolic left ventricular function before and after
catheter ablation: If AF begets AF, does pulmonary vein isolation terminate the
vicious circle? Cardiol J. 2019 Jan 31. doi: 10.5603/CJ.a2019.0004. [Epub ahead
of print] PubMed PMID: 30701515.

Alfred S. -


Thanks for compliment.

I agree that spontaneous cardioversion of 70 % is significant. However, as Swami and I discussed, that still leaves 30% who did not convert. More importantly, you don't know when they converted was it when they walk out the door of the ED or was it at 47 hours when they walked back into the ED for their recheck. But here are the other down sides of not treating them on their initial visit.

1. A-fib for any period of time reconditions the heart to more episodes and longer durations. In fact most of the reconditioning occurs in the first 24 hours of the arrhythmia. (see the references above) That is not fair to the patient.

2. If you do not convert the patient, you need to anticoagulant them which carries its own risks

3. You need to arrange the repeat visit, which as Swami said is likely to be back in the ED.

The way I view it, I would not like to take a 30% risk of all the complications associated with a-fib and anticoagulation on the gamble it will revert spontaneously.

Thanks for the comments.


Gabe W. -

All good points.
As far as point one, these patients can be going in and out of atrial fibrillation workout realizing it. We’re seeing this now with Apple Watch notifications of AFib +\- RVR so it feels somewhat arbitrary to choose one episode to cardiovert just because we are aware of it.

Your point that if it particularly disruptive and symptomatic - that’s a good reason to cardiovert.

2. Lots of people are on anticoagulation for years. A few days has minimal to no risk.

3. They’re going to require close follow up anyway.

Maybe my point is that after digesting this study, the decision to cardiovert should not be reflective but rather, a weighing of risks, benefits, patient preference, and local ability to arrange follow up - all pints you mentioned.

Clearly a pretty complex topic with much to consider.

Gabe W. -

Reflexive - not reflective. Though reflective too! Apologies for typos.

It’s amazing to me how many considerations we weigh in our career - and this is just one of many illnesses we deal with.

I think we don’t give ourselves enough credit for the depth and granularity our of thought processes and the brevity with which we have to devote to any specific patient and condition. These offline discussions are incredibly helpful.

Rebecca H. -

from my beloved up to date:
Most patients with new onset AF of longer than 48 hours duration should have cardioversion postponed until three weeks of effective anticoagulation has been achieved or a transesophageal echocardiogram has been performed and shows no left atrial appendage clot [10].

which is also what I remembered from residency so this Snack left me anxious. Most of my new onset AFibbers have no idea when it started, are rarely on anticoags and I'm not going to get a TEE in my ED. Therefore I admit most of my new onset AFib to have these things handled, abet obs status but still, I'm not shocking and discharging. So just to be clear - you are cardioverting most of these pts sans Echo and anticoagulation?

Feeling very out of touch with modern times

Anand S. -

Rebecca - I would only convert patients who have a clear time of onset within the 48-72 hour window. Honestly, I'm even a bit more conservative now and stick to the < 48 hour window. The risk of forming a clot with < 48 hours of AF is very small and a number of studies have been done converting patients in that window without causing thromboembolic events.
If there isn't a clear time of onset, I'm not reaching for cardioversion without a TEE first.
Here's a fairly comprehensive post: https://coreem.net/core/recent-onset-atrial-fibrillation/

Alfred S. -


You make all good points. Cardioversion should not be a reflex but should take into account all the aspects of the patient and their wishes.


Alfred S. -


As usual I agree with Swami, you need to be very clear of the onset time or have some device you can interrogate such as an AID or even an activity tracker.

Even with those restrictions we still do a number of ED cardioversions and discharges based only on patient history. In fact we presented a study at SAEM last week "Can Patient History Alone Identify Candidates for Safe ED Cardioversion of Recent Onset Atrial Fibrillation" in which we treated 446 patients over a 50 month period.

One other point. Even if the patient cannot identify an onset time you can still discharge them. The newer DOAC's allow you to rate control these patients in the ED, then discharge them on anticoagulants for outpatient TEE and or follow up.


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EM:RAP 2019 May - SNACK Full episode audio for MD edition 10:18 min - 8 MB - M4A