Atrial Fibrillation Algorithm

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SD -

How does CAEP define cardiac ischemia? We know that AFib RVR patients often have chest pain and ST depressions on ekg from the rate. Are they recc to cardiovert those patients?

Susy D, MD -

Thanks for listening and for the question. CAEP defines cardiac ischemia in their checklist as 'ongoing severe chest pain or marked ST depression (>2 mm) on ECG despite therapy.'
I think this is where clinical experience and gestalt enter the picture. I think we in the U.S. often shy away from cardio version, when it's actually a quick and effective treatment option in appropriate patients.

Jeffrey F. -

It’s amazing to me how many patients I see in the ER with a chads2vasc of zero. The Swedish Atrial Fibrillation Cohort study found a total of 5343 patients with a score of zero to have an annual stroke risk of 0.2% when not on anticoagulation. Patients with a chads2vasc score of 1 only had an annual stroke risk of 0.6%. From what I gathered from this podcast and the CAEP guidelines is that we should consider placing these patients on AC, even 20-year old’s with Holiday Heart Syndrome!

Risk of major bleeding for someone who is on Xarelto with a fib who has a chads2vasc of zero is estimated to be around 0.2-0.3%. Similarly, risk of major bleeding for a chads2vasc of 1 is around 0.6%.

My question is why should we put a low-risk patient on short term (4 weeks) anticoagulation when the risk of major bleeding would essentially be the same as the patient having a stroke long term? short term stroke risk is high in the few days following an a fib but this too seems to only apply to patients with other risk factors and high chads2vasc. How can we have a shared decision making conversation with the patient about AC when the guidelines don't agree and there is insufficient data? I imagine the conversation going like this: " You have a fib, in theory your risk of having a stroke long term is less than 1% but may be higher short term, you could take a blood thinner to lower that risk, but the medication comes with a risk of major bleeding that is also less than 1%. Some guidelines say we can consider starting the medication but not everyone agrees. My recommendation would be to......."

Susy D, MD -

I don't think patients with a low CHA2DS2VASc need anticoagulation. I think our patient populations will vary somewhat depending on our practice environment; for example, the majority of my patients are 1 or higher. I use the HAS-BLED for bleeding risk and the KEY is arranging follow up. If you are able to have your patient re-evaluated in a few days, the ultimate decision can be based on conversations with the PCP or cardiologist. I also can't emphasize the importance of shared decision making when choosing to/not to proceed with anticoagulation. Let's not forget that up to 20% of strokes are caused by afib. Hope this helps and thank you for listening!

Susy D, MD -

I'm not sure if I completely understand your question.
CHA2DS2-VASC score of zero does not require AC, score of 1 (men) requires either aspirin or AC (this is where I find shared-decision making helpful; one option if you have short term cardiology or PCP f/u is to start aspirin and defer more complex question of DOAC/warfarin), and any score >1 is AC (unless contraindicated).

If, however, the patient undergoes rhythm control in the ED, they should be started on anticoagulation if AF duration unclear or >48 hours regardless of stroke risk. What to do if AF onset is <48 hours is more controversial for low risk patients, with CAEP recommending AC and AHA stating oral AC not needed. Agree, this is another area shared decision is useful. CorePendium has an AFib Chapter which provides guidance and references. Thanks for listening and for the feedback!

Jeffrey F. -

Thank you for getting back so quickly!

My concern is that the proposed algorithm or method for deciding short term anti coagulation in patients who have chads2vasc scores of zero or even 1 seems arbitrary. Let me give an example to explain... A 36 year old male comes in with palpitations for 3 days and is found to have a fib. Let's say he is already rate controlled or is rate controlled after a 5mg push of metoprolol. The provider chooses to not cardiovert the patient because the risk of "causing a stroke" from embolization is too high after 48 hours. The provider then reasons that the patient can go home without anticoagulation because he has a chads2vasc score of zero. But this would be flawed logic because the decision to not cardiovert was due to the possibility of there being a thrombus in the left atrium but then the provider chose to not start the patient on anticoagulation! Furthermore, the patient will likely spontaneously convert at home before following up with cardiology which should in theory carry similar risk of causing embolization as a chemical cardioversion. Not sure if electrical cardioversion is associated with greater stroke risk? It may be that stunning or shocking the heart is more likely to result in dislodging or causing emboli?

You could also argue it doesn't make sense to start short term anticoagulation on patients with an annual stroke risk of 1/500. if 1/500 patients with chads2vasc of zero have a stroke over a period of 1 year, that risk would still be 1/500 whether it happens at 4 weeks from their diagnosis or 4 months. And most a fib patients will have additional paroxysmal episodes within a year.

Lastly there is some data to suggest that aspirin can actually carry similar bleeding risk than DOACs and does not prevent strokes in a fib as well as DOACs, So I think you could also argue that we should not be considering aspirin anymore for these lower risk patients.

Nicholas M. -

Ive spoken to cardiologist consultants that suggest that up to 50% of new onset A fibbers who start a beta blocker for rate control, revert to NSR within 1 week.
If that's true, why are we not worried about ensuring 3 weeks of anticoagulation before subjecting patients to a 50% chance of spontaneous cardioversion by treat them with rate control agents?
I've never seen this pitfall addressed in any guidelines.

Susy D, MD -

Yes, your cardiologists comments are in line with current evidence. In a 2019 NEJM study by Pluymaekers et al, investigators found that nearly 70% of patients converted to NSR in 48 hours. Which is why I personally usually go for rate control, instead of tying up staff for procedure etc. I choose to AC based on CHA2DS2-VASc. The majority of patients will have recurrent afib so will still need anticoagulation despite having converted this time.
And again, these patients all need super short term follow up with PCP or cardiologist. At my previous institution, AC decisions were usually delayed until 2-3 days follow-up in an [awesome] afib clinic. Lastly, another plug for shared decision making with your patients!
Thank you for listening and for your comments. Susy

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EM:RAP 2021 November SNACK: Atrial Fibrillation Algorithm Full episode audio for MD edition 12:28 min - 15 MB - M4A