The Timing of Cardioversion in AF

Here we review the RACE7 ACWAS (Rate Control vs Cardioversion Trial7-Acute Cardioversion versus Wait and See) Trial (1).

What they did

This was a multicenter, randomised, open label, non-inferiority trial.

They wanted to see if a wait and see approach was non-inferior to early cardioversion for obtaining sinus rhythm.

N=437

Patients with symptomatic AF presenting <36 hours after onset, were assigned to delayed vs early cardioversion.

The wait and see group received beta blockers, or calcium channel blockers or digoxin to achieve a heart rate < 110 and relief of symptoms. They were then discharged and referred back for review the next day, at which point if they were still in atrial fibrillation they were cardioverted.

The early cardioversion group, were cardioverted with flecainide, or if this was contraindicated, or they had had unsuccessful pharmacologic cardioversion previously, they were electrically cardioverted.

Patients at high risk of stroke were commenced on anticoagulation either before or immediately after cardioversion.

The Primary Outcome was sinus rhythm on ECG at 4 weeks post visit.

Secondary Outcomes included:

• Duration of Emergency department visit.
• Return visit to ED for recurrence of atrial fibrillation
• Cardiovascular complications
  • Heart failure
  • Ischaemic stroke
  • TIA
  • Unstable angina or acute coronary syndrome
  • Symptomatic bradycardia or tachycardia
  • Hypotension

What they found

In the delayed-cardioversion group

• 97% achieved sinus rhythm whether by spontaneous or delayed cardioversion
  • Spontaneous cardioversion to sinus rhythm occurred in 69% (150/218)
  • 28% (61/218) achieved sinus rhythm after delayed cardioversion
• 91%(193/212) were in sinus rhythm at 4 weeks (non-inferior)

In the early-cardioversion group

• 94% achieved sinus rhythm
  • 16% (36/219) spontaneous cardioverted prior to attempted cardioversion
  • 78%(171/219)achieved sinus rhythm after cardioversion
    • ( 83 pharmacologic and 88 electrical)
  • 94%(202/215) were in sinus rhythm at 4 weeks

Cerebral embolism occurred in two patients in this trial:

• In one patient with spontaneous cardioversion at day 5, whilst receiving anticoagulation (CHA₂DS₂-VASc score 2)
• In one patient at 10 days post electrical cardioversion, on anticoagulation (CHA₂DS₂-VASc score 3)

My Take on This

In this study 69% of patients spontaneously cardioverted, without treatment. We know it's true that over 2/3 of patients spontaneously cardiovert. Our goal is to work out the characteristics of those patients who are more likely to spontaneously cardiovert. perhaps a score similar to the ReSinus Score(2) will be useful. if we are sending patients home, we need to ensure followup the next day, not for just the patients that are asymptomatic, but for all patients as asymptomatic AF is not uncommon. We must also ensure that we assess which patients are at higher risk of stroke and anticoagulate appropriately.

Reference

1. Pluymaekers N et al. Early or Delayed Cardioversion in Recent-Onset Atrial Fibrillation. NEJM 2019;380:1499-1508
2. Niederdockl J et al. Predicting Spontaneous Conversion to sinus rhythm in symptomatic atrial fibrillation: The ReSinus score. Eurpo J Int Med. 2021;83:45-53