Critical Care, Cardiology, Critical Care Roadblock

Roadblock: AFib with RVR

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Welcome to the EMRA Critical Care Committee's Roadblock series - the resuscitationist's guide to overcoming the obstacles in the normal algorithm of critically ill patients. Through this series, we will ask the opinions of both EM and CCM fellows/attendings on their approaches to the most common obstacles encountered in a treatment algorithm. 

AFib with RVR

In this paper we focus on strategies to bypass the most common pitfalls in our treatment algorithm when treating patients who present to the ED in atrial fibrillation with RVR.

We all know the few medications in our toolbox that we can use to generally control the rate, but what if a wrench is thrown in our pathway? Are there certain medications to be used in specific instances? How are we defining an unstable patient? How much of the atrial fibrillation is contributing to the patient's instability?

We asked Sean Hickey, MD, Assistant Professor of Anesthesia and Emergency Medicine at Kick School of Medicine/USC, and  Mark Andreae, MD, Assistant Professor of Emergency Medicine and Critical Care at Mount Sinai, how they approach the most common roadblocks when treating patients in AFib with RVR.

Q: What if the patient becomes unstable? How are you defining an unstable patient?

Dr. Hickey: The term "unstable" is a complex word in medicine. This can range from having a poor mental status, poor perfusion (evidenced by an increasing lactate, decreased cap refill time, decreased UOP, mottled skin), to hypotension. You also need to determine if the AFib w/RVR is brand-new in onset or chronic before you proceed to the next step in management.

Dr. Andreae: The most important thing you need to know when treating these patients is knowing what the primary process is that is driving the AFib w/RVR. Are they unstable because of their AFib w/RVR or is it because of their primary process (eg, sepsis)? If a patient is in AFib w/RVR with rates >150 bpm, a rising lactate, worsening hypotension, and/or declining mental status I am more likely to cardiovert them because I have deemed they are unstable from the AFib w/RVR despite our attempts to treat their primary process.

Q: What if the patient has failed 1st line therapy from a beta-blocker or calcium channel blocker?

Dr. Hickey: The big question is to determine why they are in AFib w/RVR. Is it because they forgot their medication? If so, I will most likely just resume their oral home medications, whether it is a beta-blocker or calcium channel blocker. Is it because they are septic? If that is the case, then most likely their RVR is an appropriate tachycardic response and I would not give any additional beta-blocker or calcium channel blocker. I would instead treat their sepsis and give them fluids, antibiotics, etc. Are they in RVR because of their poor EF? In that case, I would consider adding an inotropic agent like milrinone or epinephrine in addition to amiodarone. I am not worried about controlling their rates until they are in the 120s/130s. 

Dr. Andreae: If a patient is on metoprolol as a home regimen, I will first give metoprolol in the ED. If that fails I will try giving a calcium channel blocker. The same applies in the opposite direction if the patient is taking a calcium channel blocker as their home medication. I would be cautious of certain contraindications (eg, calcium channel blockers in patients with HF and beta-blockers in patients with an asthma exacerbation). A reasonable 3rd line would be to use amiodarone. However, there is also an increased risk of cardioversion using amiodarone. Beware of its use in patients with active thyroid and liver disease.

Q: When are you considering synchronized cardioversion as a treatment modality? If you are using cardioversion, how many (J) are you initially starting with? What is your sedation/analgesia approach for cardioverting a patient?

Dr. Hickey: Synchronized cardioversion is always part of my treatment modality. If the patient has new AFib w/ RVR and meets criteria for ED DCCV and discharge, as evidenced by Ottawa Aggressive Atrial Fibrillation Protocol, then I would cardiovert them after having a conversation with cardiology and have them follow up outpatient. If they are unstable from their AFib w/RVR then I will also DCCV. In terms of sedation, I would use propofol. However, a lot of EM physicians like to use etomidate.

Dr. Andreae: If a patient is truly unstable from their AFib w/RVR I will DCCV. Another population I would strongly consider cardioverting are those with structural heart abnormalities such as severe aortic stenosis. These individuals usually need additional diastolic time for left ventricular filling and therefore do not tolerate AFib w/RVR well because of the tachycardia. I would consider cardioverting them in order to help them increase their diastolic filling time. I will always start high with 200J to cardiovert these patients. In preparation, I will use Fentanyl for analgesia and etomidate for sedation. I will dose etomidate lower than the typical induction dose and use around 0.1 mg/kg. Given the risk of hypotension, I will also have a vasopressor readily available.

Q: What if the patient is hypotensive to SBP <90s with a normal vs abnormal mental status?

Dr. Hickey: As mentioned, you need to determine the overall clinical context of the patient. Are they hypotensive because of their underlying process or is the AFib w/RVR driving the hypotension?

Dr. Andreae: A mental status is just one data point in determining if the patient is truly stable or unstable. If a patient is clinically appearing well with a SBP <90 I wouldn’t necessarily jump to cardioverting the patient. However, if they have a poor mental status that is changed from their baseline with a hypotensive blood pressure, I am more likely to cardiovert the patient. You have to also consider the underlying etiology of their AFib w/RVR and treat them appropriately.

Q: What if the patient has a history of severe systolic HF?

Dr. Hickey: I would give the patient amiodarone and consider cardioverting the patient. In addition, I would consider diuresising the patient and adding an inotropic agent. You need to always be treating the underlying disease process.

Dr. Andreae: I would avoid agents such as calcium channel blockers in patients with a history of HF. I would start by diuresing the patient and giving a beta-blocker to help with rate control. In particular, with patients with severe atrial or mitral stenosis, I would be more aggressive about cardioverting these patients since they do not tolerate the RVR response well physiologically as described above.

Q: What if the patient is in AFib with Wolff-Parkinson-White?

Dr. Hickey: DCCV. Procainamide is an acceptable answer, but the practical answer is DCCV.

Dr. Andreae: This is a very scary EKG to see. You should avoid any nodal blocker such as amiodarone, calcium channel blocker, and beta-blockers. You should DCCV these patients. If the patient is stable, Procainamide is an option but would strongly advocate for DCCV. Procainamide is also known to cause hypotension.

Q: When in your practice are you considering magnesium vs. amiodarone vs. digoxin for treatment?

Dr. Hickey: I always give a magnesium bolus of 2 g in the ED. I also will keep their magnesium level above 2.2. Amiodarone is always the right answer except in WPW. I would not get fancy with giving digoxin in the ED setting.

Dr. Andreae: I will always try to give magnesium, especially if they have electrolyte abnormalities. Amiodarone is a great agent to use; however, be aware of side effects with patients with liver disease as well as the risk of cardioverting the patient. I will not give digoxin in the ED unless someone is taking it as a home medication. I would use caution with digoxin, especially with patients with CKD/ESRD. If you need to give it in the ED, I would have a discussion with cardiology.

Discussion

The approach to AFib w/RVR is a form of art and is highly dependent on the patient’s clinical picture. From the conversation with Dr. Hickey and Dr. Andreae, the most important aspect of treating patients who present with Afib RVR is to determine the patient's primary process. When assessing these patients, it's important to look at the entire clinical picture. Are they in AFib w/RVR because of their underlying disease process (eg, sepsis, ischemia, PE, etc.)? If so, you need to treat their underlying etiology as a first-line therapy as opposed to directly controlling their rate. Using a bedside POCUS can play a big role because it gives you a sense of how their squeeze is and their overall RV/LV function. It can also help to rule out any effusions.

When controlling a patient's rate, keep in mind what they already take at home and if they have any certain contraindications to medications (eg, avoiding calcium channel blockers in HF patients, beta-blockers in asthma exacerbations, or amiodarone in active liver/thyroid disease).

When assessing their clinical stability, remember that it is a compilation of data points. It is important to assess the patient's mental status, blood pressure, lactate, and urinary output to gain a broader perspective on the patient's stability. As part of the algorithm, if patients are truly unstable from the above markers or they have structural heart abnormalities, they may need DCCV.


Through this series, we hope you are a little better equipped to deal with an obstacle the next time a patient presents with Afib w/RVR to your ED. Stay tuned for the next installment, in which we tackle roadblocks associated with difficult intubations.

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