How to manage atrial fibrillation in the Emergency Room (ER)?

Emergency Department Management of Atrial Fibrillation

For atrial fibrillation in the ER, immediately assess hemodynamic stability: if unstable (hypotension, shock, pulmonary edema, altered mental status, or ongoing chest pain), perform immediate electrical cardioversion without delay for anticoagulation; if stable, pursue rate control with IV diltiazem or metoprolol as first-line agents, initiate anticoagulation based on stroke risk, and consider rhythm control for new-onset AF or highly symptomatic patients. 1, 2, 1

Step 1: Assess Hemodynamic Stability (First Priority)

Unstable patients require immediate action:

• Perform immediate electrical (DC) cardioversion if the patient exhibits hypotension, shock, pulmonary edema, acute heart failure, ongoing myocardial ischemia/chest pain, or decreased level of consciousness 1, 2, 1
• Do NOT delay cardioversion for anticoagulation in unstable patients 2, 1
• Begin IV heparin bolus followed by continuous infusion immediately after cardioversion 2
• Continue anticoagulation for at least 4 weeks post-cardioversion regardless of rhythm outcome 2, 1

Special exception - WPW syndrome with pre-excited AF:

• If hemodynamically unstable: immediate DC cardioversion 2, 1
• If stable: use IV procainamide or ibutilide (NOT AV nodal blockers like diltiazem, metoprolol, digoxin, or adenosine, as these can accelerate ventricular rate and precipitate ventricular fibrillation) 3, 2

Step 2: Rate Control for Stable Patients (Primary Strategy in ER)

First-line IV agents for rate control:

• IV Diltiazem: 0.25 mg/kg IV bolus over 2 minutes (typically 15-25 mg), may repeat with 0.35 mg/kg after 15 minutes if inadequate response, then continuous infusion at 5-15 mg/hour 1, 4
• IV Metoprolol: 2.5-5 mg IV bolus over 2 minutes, up to 3 doses separated by 5 minutes (maximum 15 mg total) 1, 3
• IV Esmolol: 500 mcg/kg IV bolus over 1 minute, then 50-300 mcg/kg/min continuous infusion (useful for very rapid titration in unstable situations) 1, 3

Diltiazem achieves rate control faster than metoprolol based on comparative studies, though both are safe and effective 5

Target heart rate:

• Lenient control: <110 bpm at rest (acceptable initial approach for most stable patients) 3, 6
• Strict control: 60-80 bpm at rest (if lenient control fails to control symptoms) 1, 3

Agent selection based on comorbidities:

• Preserved ejection fraction (LVEF >40%): Use beta-blockers OR non-dihydropyridine calcium channel blockers (diltiazem/verapamil) as first-line 1, 3, 6
• Reduced ejection fraction (LVEF ≤40%) or heart failure: Use beta-blockers and/or digoxin; AVOID calcium channel blockers 1, 3, 1
• COPD or active bronchospasm: Use diltiazem or verapamil; AVOID beta-blockers 3, 6
• Hyperthyroidism or high catecholamine states: Prefer beta-blockers 3

Digoxin limitations in the ER:

• Onset of action delayed 60+ minutes, peak effect at 6 hours 1
• Ineffective as sole agent for paroxysmal AF, especially in high sympathetic states 1, 6
• Reserve for patients with heart failure or as adjunct to beta-blockers 1, 3

Step 3: Anticoagulation Decision (Parallel to Rate Control)

Assess stroke risk using CHA₂DS₂-VASc score:

• Congestive heart failure (1 point)
• Hypertension (1 point)
• Age ≥75 years (2 points)
• Diabetes (1 point)
• Prior stroke/TIA/thromboembolism (2 points)
• Vascular disease (1 point)
• Age 65-74 years (1 point)
• Sex category female (1 point)

Anticoagulation recommendations:

• Score ≥2: Initiate anticoagulation in the ER 3, 6
• Preferred agents: Direct oral anticoagulants (DOACs) over warfarin 1, 6
  • Apixaban 5 mg twice daily (or 2.5 mg twice daily if ≥2 of: age ≥80, weight ≤60 kg, creatinine ≥1.5 mg/dL) 3
  • Rivaroxaban, edoxaban, or dabigatran at standard doses 6
• Warfarin alternative: Target INR 2.0-3.0 with weekly monitoring initially 3

Critical timing rules for cardioversion:

• AF duration <24 hours: May cardiovert without prior anticoagulation if low stroke risk, but initiate anticoagulation immediately after 1
• AF duration 24-48 hours: Anticoagulate before cardioversion if stroke risk factors present 1
• AF duration >48 hours or unknown: Require 3 weeks therapeutic anticoagulation before elective cardioversion OR perform transesophageal echocardiography to rule out left atrial thrombus 1
• Post-cardioversion: Continue anticoagulation for minimum 4 weeks, then long-term based on CHA₂DS₂-VASc score 1, 2

Step 4: Consider Rhythm Control (Selected Patients)

Candidates for rhythm control in the ER:

• New-onset AF (<48 hours) in highly symptomatic patients 1, 6
• AF with heart failure where AF may be contributing to decompensation 3
• Young patients with lone AF and no structural heart disease 7

Pharmacological cardioversion options (if anticoagulation criteria met):

• No structural heart disease: Flecainide or propafenone IV 1, 3
• Coronary artery disease or structural heart disease: IV ibutilide or amiodarone 1
• Heart failure or LVEF <40%: Amiodarone only (300 mg IV over 1 hour, then 10-50 mg/hour) 1, 3

Electrical cardioversion technique:

• Synchronized DC cardioversion starting at 120-200 joules biphasic 1
• May adjust electrode position or apply pressure if initial attempt unsuccessful 1
• Response typically occurs within 3 minutes 4

Step 5: Identify and Treat Reversible Causes

Evaluate for secondary AF triggers:

• Acute coronary syndrome (troponin if chest pain or high-risk features) 8
• Pulmonary embolism (consider if dyspnea, hypoxia, or risk factors present) 9
• Thyrotoxicosis (TSH if new-onset AF or unexplained weight loss) 3
• Electrolyte abnormalities (check potassium, magnesium) 9
• Sepsis or acute infection 9
• Alcohol intoxication ("holiday heart") 9
• Postoperative state 3

Step 6: Disposition Decision

Admit to hospital if:

• Hemodynamically unstable requiring cardioversion 2
• New-onset heart failure or decompensated heart failure 8
• Acute coronary syndrome or elevated troponin with ischemic features 8
• Failed rate control in the ER 8
• Significant comorbidities requiring inpatient management 9
• New diagnosis requiring workup (echocardiogram, etc.) 9

May discharge if:

• Hemodynamically stable with adequate rate control achieved 9, 8
• No acute precipitating illness requiring admission 9
• Reliable for outpatient follow-up within 1-2 weeks 9
• Anticoagulation initiated or plan established 9
• Patient educated on warning signs 9

Critical Pitfalls to Avoid

• Never use AV nodal blockers (diltiazem, metoprolol, digoxin, adenosine) in WPW syndrome with pre-excited AF - can cause ventricular fibrillation 3, 2
• Never use calcium channel blockers in patients with heart failure and reduced ejection fraction - can worsen heart failure 1, 3
• Never delay cardioversion for anticoagulation in unstable patients - hemodynamic stability takes priority 2, 1
• Never discharge without addressing anticoagulation - stroke risk persists regardless of rhythm 6
• Never rely on digoxin alone for acute rate control - onset too slow and ineffective in high sympathetic states 1, 6
• Never underdose or inappropriately discontinue anticoagulation - dramatically increases stroke risk 6