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Myths in Emergency Medicine

The Quixotic Quest to Control Atrial Fibrillation

Spiegel, Rory, MD

doi: 10.1097/01.EEM.0000559968.01416.aa
Myths in Emergency Medicine

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Very little about the management of atrial fibrillation is an emergency, yet we in emergency medicine have embraced it as one. We gleefully bring to bear the full technological powers available to us to tame its irregular irregularity. Using this aggressive approach has proven that we are quite adept at controlling atrial fibrillation, discharging the majority of patients home in sinus rhythm. (Ann Emerg Med. 2017;69[5]:562; http://bit.ly/2InMRzq.)

But to what end? The recent publication of the RACE-7 trial by Pluymaekers, et al., highlights just how absurd and wasted our struggles toward sinus normalcy are. (N Engl J Med. March 18, 2019; doi: 10.1056/NEJMoa1900353.) The authors enrolled adults presenting to 15 EDs in the Netherlands with stable, recent-onset, symptomatic atrial fibrillation (defined as starting within 36 hours of presentation).

Patients were randomized to immediate cardioversion in the ED or a delayed approach. Those in the delayed strategy group received rate-controlling medication in the ED and were then discharged with a plan to follow up in 48 hours. Patients were assessed at 48 hours to determine if they remained in atrial fibrillation, and if so, they were sent back to the ED for immediate cardioversion.

The researchers randomized 437 patients over a four-year period, 218 to the delayed cardioversion group and 219 to the early cardioversion group. The cohort overall was fairly representative of patients who typically present to the ED for symptomatic atrial fibrillation. The mean age was 65, 40 percent were female, 44 percent presented with their first episode of atrial fibrillation, 64 percent had a CHA2DS2-VASc score of 2 or higher, and 40 percent were taking oral anticoagulants at the time of presentation.

Reversion to sinus rhythm occurred in 94 percent of the patients randomized to the immediate cardioversion strategy; 16 percent experienced spontaneous cardioversion and 78 percent underwent chemical or electrical cardioversion (37.9% and 40.2%, respectively). Ninety-eight percent of the patients in the delayed group achieved rate control in the ED: 71 percent with a beta-blocker, 2.3 percent with a non-dihydropyridine calcium-channel blocker, and six percent with digoxin. Rate control was achieved in 19 percent without the assistance of any medication.

Despite their almost-universal success in the early cardioversion group at achieving sinus rhythm prior to discharge, the authors observed no difference in their primary endpoint, the presence of sinus rhythm on the ECG recorded at the four-week visit, which was observed in 91 percent in the delayed cardioversion group and 94 percent in the early cardioversion group. This 2.9 percent difference met the authors' noninferiority margin of 10% (95% CI−8.2 to 2.2; P=0.005 for noninferiority).

The authors also did not find any difference in any of their secondary endpoints. Almost all the patients in both groups were discharged following the index ED visit. ED revisits for atrial fibrillation was seven percent in both groups. No differences were observed in the rate of cardiovascular complications, 10 in the delayed cardioversion group (including one with ischemic stroke and three with acute coronary syndrome or unstable angina), and eight in the early cardioversion group (including one with transient ischemic attack and three with acute coronary syndrome or unstable angina). Total median duration of the index visit was 120 minutes in the delayed cardioversion group and 158 minutes in the early cardioversion group.

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Flaws and Insights

This trial is far from ideal. It compared an immediate approach to a slightly less emergent one, leaving us all wondering what they would have found if they had not attempted to control the rhythm at all. The primary endpoint—the number of patients in sinus rhythm at one month—holds no clinical meaning because, as we have known for some time, a rhythm control strategy does not lead to better outcomes.

Flaws aside, this trial does give us some insight into the true futility of our emergency endeavors for early rhythm control. Sixty-nine percent of the patients at the 48-hour follow-up visit had spontaneously converted without active cardioversion. This number would likely have been even higher if the authors had foregone delayed cardioversion in favor of a simple rate control strategy. The number of patients who experienced repeated bouts of atrial fibrillation over the first 28 days was also similar between the two groups, 30 percent and 29 percent in the delayed and immediate strategies, respectively.

No difference was seen in patients' quality-of-life scores, often cited as one of the major advantages of an immediate defibrillation strategy. Simply put, the majority of patients evaluated in the ED for stable, symptomatic atrial fibrillation will spontaneously revert to sinus rhythm by 48 hours. Immediate cardioversion had no effect on how often patients experience bouts of atrial fibrillation in the following 28 days, the number of patients in sinus rhythm at one month, and any patient-important outcomes.

Atrial fibrillation is a chronic disease with outcomes measured in years. Constraining its irregularities for the fleeting moments the patient is before us in the emergency department has minimal effect on patient outcomes or well-being. An immediate cardioversion strategy is a quixotic attempt to check a symptom that is not only incredibly difficult to control, but whose regulation has never been found to improve patient-important outcomes.

When viewed from this perspective, the futility of ED cardioversion seems obvious. It serves only as a distractor, diverting our attention from rate control and the appropriate use of anticoagulants, interventions that have proven benefits for patients' downstream health and well-being.

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Think Twice

Richard Pescatore, DO, and Ali Raja, MD, agree with Dr. Spiegel, and say they'll think twice before cardioverting every patient with atrial fibrillation. Listen to their latest EMN Live podcast: http://bit.ly/EMNLive.

Dr. Spiegelis a clinical instructor in emergency medicine and a critical care fellow in the division of pulmonary and critical care medicine at the University of Maryland Medical Center. Visit his blog athttp://emnerd.com, follow him on Twitter @emnerd_, and read his past articles athttp://bit.ly/EMN-MythsinEM.

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