What trial discusses a wait and see approach in atrial fibrillation rhythm control strategy?

Wait-and-See Approach in Atrial Fibrillation Rhythm Control

The RACE 7 ACWAS trial (2019) is the landmark study that specifically investigated and validated the wait-and-see approach for recent-onset atrial fibrillation, demonstrating that delaying cardioversion for up to 48 hours while using rate control is noninferior to immediate cardioversion. 1

The RACE 7 ACWAS Trial Design and Findings

The RACE 7 ACWAS (Acute Cardioversion versus Wait-And-See) trial was a multicenter, randomized, open-label, noninferiority trial that enrolled patients presenting to emergency departments with hemodynamically stable, recent-onset (<36 hours), symptomatic atrial fibrillation. 1

Key trial methodology:

• Patients were randomized to either a wait-and-see approach (delayed cardioversion) or early cardioversion 1
• The wait-and-see strategy involved initial treatment with rate-control medication only, with delayed cardioversion performed only if atrial fibrillation did not resolve spontaneously within 48 hours 1
• Primary endpoint was presence of sinus rhythm at 4 weeks 1

Critical results demonstrating noninferiority:

• Sinus rhythm at 4 weeks occurred in 91% of delayed-cardioversion patients versus 94% in early-cardioversion patients (difference: -2.9 percentage points; 95% CI: -8.2 to 2.2; P = 0.005 for noninferiority) 1
• In the wait-and-see group, 69% of patients converted spontaneously to sinus rhythm within 48 hours without requiring any cardioversion 1
• Only 28% of wait-and-see patients ultimately required delayed cardioversion 1
• Recurrence rates were essentially identical: 30% in delayed-cardioversion group versus 29% in early-cardioversion group 1
• Cardiovascular complications were comparable between groups (10 patients versus 8 patients) 1

Guideline Integration of Wait-and-See Approach

The most recent 2024 ESC guidelines have incorporated this evidence into their recommendations. For patients with first-diagnosed symptomatic persistent atrial fibrillation, a wait-and-see approach to allow spontaneous restoration of sinus rhythm within 48 hours receives a Class IIa recommendation. 2

The 2011 ACC/AHA/HRS guidelines also acknowledged this strategy, noting that "in patients who tolerate AF relatively well, a wait-and-see approach using oral sotalol is an appropriate option" for rate control while awaiting spontaneous conversion. 2

Supporting Evidence from Earlier Studies

A 2011 prospective observational study published in Emergency Medicine International provided earlier supporting evidence for this approach, though with a smaller sample size. 3 In this study:

• 63% of patients had spontaneous resolution of atrial fibrillation when they returned the following day for potential cardioversion 3
• All remaining patients underwent successful cardioversion without significant adverse events 3
• No patients required hospitalization 3
• All patients reported being "very satisfied" with this approach 3

Clinical Application and Patient Selection

The wait-and-see approach is appropriate for:

• Hemodynamically stable patients with recent-onset atrial fibrillation (<48 hours duration) 2, 1
• Patients without urgent indications for immediate cardioversion (no hypotension, acute heart failure, ongoing chest pain, or altered mental status) 4
• Symptomatic but tolerating the arrhythmia reasonably well 2

Critical exclusions where immediate cardioversion is required:

• Hemodynamic instability 4
• Acute heart failure or worsening heart failure 2
• Ongoing myocardial ischemia 4
• Wolff-Parkinson-White syndrome with rapid ventricular response 4

Practical Implementation

When employing the wait-and-see strategy:

• Initiate rate control medication (beta-blockers as first-line for most patients, or non-dihydropyridine calcium channel blockers for those with preserved ejection fraction) 4
• Target lenient rate control initially (resting heart rate <110 bpm) 2
• Ensure appropriate anticoagulation based on CHA₂DS₂-VASc score and duration of atrial fibrillation 4
• Plan for reassessment within 48 hours of symptom onset 1
• Proceed with cardioversion if spontaneous conversion has not occurred by 48 hours 2, 1

The major clinical advantage is that nearly 70% of patients avoid unnecessary cardioversion procedures, procedural sedation, and the associated risks and costs, while achieving equivalent outcomes. 1