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For Recent-Onset Afib, Delayed Cardioversion Noninferior to Early Treatment

In patients with new-onset atrial fibrillation (Afib), outcomes following early cardioversion performed soon after presentation to the hospital emergency department were similar to those of patients who received delayed cardioversion in a multicenter study from the Netherlands.

Taking a wait-and-see approach was found to be noninferior to early cardioversion in the randomized RACE 7 ACWAS (Rate Control vs Electrical Cardioversion Trial 7-Acute Cardioversion vs Wait and See) trial, which was designed to determine if immediate restoration of sinus rhythm is associated with improved outcomes in patients presenting with new-onset Afib.

Early cardioversion performed soon after presentation to the emergency department was not associated with significantly more patients having normal heart rhythm a month later in the trial, which was published online in the New England Journal of Medicine.

In an editorial published with the study, Jeff S. Healey, MD, and William F. McIntyre, MD, of McMaster University in Ontario, Canada, wrote that the RACE 7 trial results “greatly simplify the current controversy regarding the safety or cardioversion between 12 and 48 hours after the onset of atrial fibrillation.”

“For most patients with recent-onset atrial fibrillation, the wait-and-see approach may become the preferred strategy, unless they have a history of persistent atrial fibrillation or there are barriers to implementing this approach,” Healey and McIntyre wrote.

In an interview with MedPage Today, Healey said there is a large degree of variability in how patients with new-onset Afib are managed in hospital emergency departments, with some treated with cardioversion and others given rate-control medications.

“In this particular patient population the best course of action has not really been studied,” he said.

The trial included stable patients with recent-onset (i.e., less than 36 hours) symptomatic Afib presenting to 15 hospital EDs in the Netherlands from October 2014 through September 2018 and randomized to either early cardioversion or a wait-and-see approach (delayed cardioversion group).

The wait-and-see group received initial treatment with a rate-control medication only, and cardioversion was performed only if the Afib did not resolve within 48 hours. The primary endpoint was the presence of sinus rhythm 4 weeks after presentation, and noninferiority was established if the lower limit of the 95% confidence interval for between-group difference in the primary endpoint in percentage points was more than -10.

Sinus rhythm occurred in 193 of 212 patients (91%) in the delayed-cardioversion group and 202 of 215 patients (94%) in the early-cardioversion group (between-group difference, -2.9 percentage points, 95% CI, -8.2 to 2.2; P=0.005 for noninferiority).

Among the other main findings:

  • Spontaneous conversion to sinus rhythm occurred within 48 hours in 150 of 218 delayed-cardioversion participants (69%) and after delayed conversion in 61 patients (28%)
  • In the early-cardioversion participants, conversion to sinus rhythm occurred spontaneously before the initiation of cardioversion in 36 of 219 patients (16%) and after cardioversion in 171 patients (78%)
  • Afib recurred in 49 of 164 patients who were remotely monitored during follow-up in the delayed-cardioversion group (30%) and in 50 of 171 patients in the early-cardioversion group (29%)

The RACE 7 investigators noted that the wait-and-see strategy has several advantages over performing immediate cardioversion, including possibly avoiding the procedure and its potential complications, reducing time spent in the ED, and reducing misclassification of persistent Afib when spontaneous conversion of Afib is observed.

“This (latter) factor may bear consequences for future rhythm-control strategies, which are considered to be less complex in patients with paroxysmal atrial fibrillation than in those with persistent atrial fibrillation,” the team wrote.

Healey noted that since most patients who present to EDs with new-onset Afib have recurrent episodes even when they spontaneously return to sinus rhythm, long-term management is critical: “This trial examined acute management, but much of the battle with atrial fibrillation is long-term management,” he said. “If we address long-term management after the first episode, either with anticoagulation or rate-control medication or risk factors, we can lower the risk for bad outcomes like heart failure or stroke.”

He noted that 5-10% of patients will die within a year of visiting a hospital ED due to Afib and 10% to 20% will have a stroke, embolism, heart attack, or hospitalization for heart failure.

“The risk is far from trivial,” he said.

Funding for the research was provided by the Netherlands Organization for Health Research and Development and by the Maastricht University Medical Center.

The authors reported no disclosures.


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