Rate Control Versus Electrical Cardioversion Trial 7–Acute Cardioversion Versus Wait and See - RACE 7 ACWAS

Contribution To Literature:

The RACE 7 ACWAS trial showed that delayed cardioversion was noninferior to early cardioversion at the presence of normal sinus rhythm at 4 weeks. 


The goal of the trial was to evaluate delayed compared with early cardioversion among patients with recent-onset atrial fibrillation.

Study Design

  • Randomized
  • Parallel

Patients with new-onset atrial fibrillation were randomized to delayed cardioversion (n = 218) versus early cardioversion (n = 219). Patients randomized to delayed cardioversion received rate controlling agents and underwent cardioversion in 48 hours, if needed. Transesophageal echocardiography was not performed in any patient. Long-term anticoagulation was recommended according to the patient’s estimated stroke risk.

  • Total number of enrollees: 437
  • Duration of follow-up: 4 weeks
  • Mean patient age: 65 years
  • Percentage female: 40%
  • Percentage with diabetes: 10%

Inclusion criteria:

  • Onset of atrial fibrillation <36 hours
  • Hemodynamically stable

Other salient features/characteristics:

  • In the delayed cardioversion group, 69% spontaneously converted to normal sinus rhythm before 48 hours

Principal Findings:

The primary outcome, presence of normal sinus rhythm at 4 weeks, occurred in 91% of the delayed cardioversion group compared with 94% of the early cardioversion group (p = 0.005 for noninferiority).

Secondary outcomes:

  • Ischemic stroke or transient ischemic attack: one patient in the delayed group vs. one patient in the early group
  • Cardiovascular complications: 10 patients in the delayed group vs. eight patients in the early group


Among patients with recent-onset atrial fibrillation, delayed cardioversion was noninferior to early cardioversion at maintaining atrial fibrillation at 4 weeks. Spontaneous cardioversion occurred in the majority of patients randomized to a delayed strategy before electrical or pharmacological cardioversion was required. This trial does not apply to patients in whom the duration of atrial fibrillation is unknown. Regardless of whether a rate or rhythm control strategy is selected, the patient’s risk for stroke needs to be estimated and anticoagulation initiated, if appropriate.


Pluymaekers NA, Dudink EA, Luermans JG, et al., on behalf of the RACE 7 ACWAS Investigators. Early or Delayed Cardioversion in Recent-Onset Atrial Fibrillation. N Engl J Med 2019;380:1499-508.

Editorial: Healey JS, McIntyre WF. The RACE to Treat Atrial Fibrillation in the Emergency Department. N Engl J Med 2019;380:1578-9.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Noninvasive Imaging, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Echocardiography/Ultrasound

Keywords: Anti-Arrhythmia Agents, Anticoagulants, Arrhythmias, Cardiac, Atrial Fibrillation, Brain Ischemia, Echocardiography, Transesophageal, Electric Countershock, Ischemic Attack, Transient, Secondary Prevention, Risk, Secondary Prevention, Stroke, Thrombolytic Therapy, Vascular Diseases

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