What is the initial treatment for atrial fibrillation (a fib) with a heart rate of tachycardia and stable blood pressure?

Treatment for Atrial Fibrillation at 140-160 bpm with Stable Blood Pressure

For a hemodynamically stable patient with atrial fibrillation at 140-160 bpm, initiate intravenous beta-blockers (metoprolol or esmolol) or non-dihydropyridine calcium channel blockers (diltiazem or verapamil) as first-line therapy, with diltiazem achieving rate control faster than metoprolol. 1, 2

Initial Assessment

Before initiating rate control, rapidly assess for:

• Pre-excitation syndrome (Wolff-Parkinson-White): Look for delta waves on ECG, as AV nodal blocking agents are contraindicated and can paradoxically accelerate ventricular response 1, 3
• Left ventricular function: Determine if LVEF is preserved (>40%) or reduced (≤40%), as this dictates medication selection 1, 4
• Heart failure status: Check for signs of decompensated heart failure, as non-dihydropyridine calcium channel blockers are contraindicated in this setting 1

Acute Rate Control Strategy

For Preserved LVEF (>40%)

First-line options (all Class I recommendations):

• Intravenous diltiazem: 15-20 mg (0.25 mg/kg) IV over 2 minutes; may repeat 20-25 mg (0.35 mg/kg) in 15 minutes if needed, followed by 5-15 mg/h maintenance infusion 1
• Intravenous metoprolol: 5 mg over 1-2 minutes, repeated every 5 minutes as needed to maximum 15 mg 1
• Intravenous esmolol: 500 mcg/kg loading dose over 1 minute, followed by 50 mcg/kg/min infusion, titrating up to 300 mcg/kg/min as needed 1

Diltiazem achieves rate control faster than metoprolol, though both are safe and effective. 2

For Reduced LVEF (≤40%) or Heart Failure

Use beta-blockers and/or digoxin only 1, 4:

• Intravenous metoprolol or esmolol (dosing as above) 1
• Intravenous digoxin: Loading dose for acute rate control, though onset is slower 1
• Avoid non-dihydropyridine calcium channel blockers (diltiazem, verapamil) as they may exacerbate hemodynamic compromise 1

For Pre-excited Atrial Fibrillation (WPW)

Avoid all AV nodal blocking agents (beta-blockers, calcium channel blockers, digoxin, adenosine) 1, 3:

• Intravenous procainamide: 20-50 mg/min until arrhythmia suppressed, hypotension occurs, QRS widens by 50%, or maximum 17 mg/kg reached 1
• Intravenous ibutilide: Alternative option 1

Target Heart Rate

Adopt a lenient rate control strategy initially, targeting resting heart rate <110 bpm. 1, 3

• This approach is non-inferior to strict rate control (<80 bpm at rest) for clinical outcomes including mortality, heart failure hospitalization, and stroke 1
• Reserve stricter control (<80 bpm) for patients with persistent AF-related symptoms despite achieving <110 bpm 1, 3

Transition to Oral Therapy

Once acute rate control is achieved, transition to oral maintenance therapy:

For Preserved LVEF (>40%)

• Oral beta-blockers (metoprolol, atenolol, carvedilol) 1, 4
• Oral diltiazem or verapamil 1, 4
• Digoxin (less effective as monotherapy, better for sedentary or elderly patients) 1, 4, 5

For Reduced LVEF (≤40%)

• Oral beta-blockers (carvedilol, metoprolol succinate, bisoprolol preferred in heart failure) 1, 4
• Digoxin (particularly useful in combination with beta-blockers) 1, 4

Combination Therapy

If single-agent therapy fails to control rate or symptoms, consider combination therapy (Class IIa recommendation) 1:

• Digoxin plus beta-blocker: Controls rate both at rest and during exercise 1
• Digoxin plus calcium channel blocker (if preserved LVEF): Alternative combination 1
• Monitor carefully to avoid excessive bradycardia 1

Critical Pitfalls to Avoid

• Never use digoxin as sole agent for paroxysmal AF (Class III recommendation) 1
• Never give calcium channel blockers in decompensated heart failure 1
• Never give AV nodal blockers in pre-excited AF/WPW 1
• Do not pursue overly aggressive rate control (<80 bpm) initially, as lenient control (<110 bpm) is equally effective and safer 1

Anticoagulation

Initiate antithrombotic therapy for stroke prevention in all patients with AF unless contraindicated (Class I recommendation) 1:

• Base selection on stroke risk (CHA₂DS₂-VASc score) and bleeding risk 1
• This decision is independent of rate versus rhythm control strategy 1

Refractory Cases

If pharmacological rate control fails:

• Consider AV node ablation with pacemaker implantation (Class IIa recommendation) 1, 3
• For patients with heart failure and LVEF ≤40%, consider AV node ablation with cardiac resynchronization therapy 1
• Always attempt pharmacological therapy before ablation 1