Guideline position

• If haemodynamically unstable: perform immediate synchronized electrical cardioversion. Do not delay cardioversion to give digoxin.
• If stable with HFrEF:
  • Avoid IV diltiazem and verapamil in significant LV systolic dysfunction or decompensated HF. They are only recommended for acute rate control when LVEF >40%.
  • Beta-blocker may be used cautiously if the patient is not in shock or severely decompensated.
  • IV digoxin is reasonable when beta-blockers and non-dihydropyridine calcium-channel blockers are contraindicated, ineffective, or poorly tolerated.
  • IV amiodarone is reasonable when acute AF-RVR persists in HF and beta-blockers/CCBs cannot be used or fail, particularly if faster control is required. Consider that it may cardiovert the patient, so stroke-prevention considerations matter.

Practical use of IV digoxin

• 0.25 to 0.5 mg IV, administered slowly.
• If needed, further 0.25 mg IV doses every 6 hours.
• Usual maximum total loading dose: 1.5 mg in 24 hours.

Key limitations and precautions

• Slow onset: digoxin commonly takes hours to achieve useful acute rate control. It is not ideal when an immediate reduction in ventricular rate is necessary. The ACC guideline notes IV diltiazem lowers rate more rapidly in appropriate patients, but diltiazem is generally unsuitable in HFrEF.
• Best for resting rate: it may be less effective during high sympathetic tone, such as sepsis, pain, hypoxia, or exertion.
• Check and correct potassium, magnesium, calcium, renal function, and interacting medicines.
• Monitor ECG, heart rate, renal function, and, when indicated, digoxin concentration. In chronic HF therapy, lower serum levels, usually <1.0 ng/mL, are associated with better safety; avoid unnecessarily high levels. A 2024 systematic review focused on AF with reduced EF also supports caution about higher concentrations (PMID 38000566).
• Do not use AV-nodal blockers including digoxin in pre-excited AF/WPW, because they can accelerate conduction through the accessory pathway and trigger ventricular fibrillation.
• Digoxin controls ventricular rate. It does not substitute for assessment of cardioversion, anticoagulation, precipitating causes, and long-term rhythm-control options.

1. Immediate assessment

• Hypotension or shock
• Acute pulmonary oedema or severe worsening HF
• Ongoing ischaemic chest pain
• Syncope, altered mental status, or signs of poor perfusion

2. If unstable: synchronized electrical cardioversion

• Immediate synchronized DC cardioversion is indicated.
• Do not wait for digoxin to work.
• Give anticoagulation as soon as feasible unless contraindicated, but do not delay life-saving cardioversion for anticoagulation.

3. If stable: acute ventricular-rate control in HFrEF

Avoid

• IV diltiazem or verapamil in HFrEF/significant LV systolic dysfunction. Their negative inotropic action can worsen HF.
• Avoid AV-nodal blockers, including digoxin and beta-blockers, in pre-excited AF/WPW.

Preferred practical options

Digoxin in this scenario

• Useful when HFrEF is decompensated or BP is too low for beta-blockade.
• Not a rapid rescue drug. Rate reduction may take hours.
• Dose must be individualized for age, lean body weight, renal function, potassium/magnesium, and interacting drugs.
• Monitor for bradyarrhythmia, AV block, ventricular ectopy, nausea, confusion, and toxicity.

4. Other acute measures

• Give IV magnesium if low, and guideline-supported IV magnesium adjunctively may help establish/maintain rate control.
• Treat congestion with appropriate IV diuresis if fluid overloaded.
• Continue or optimize HFrEF guideline-directed therapy once stable, but do not initiate or aggressively up-titrate beta-blocker during shock or severe decompensation.
• Reassess rate, perfusion, symptoms, BP, urine output, and lung congestion frequently.

5. Anticoagulation and rhythm strategy

• Assess stroke risk and initiate anticoagulation unless contraindicated.
• If AF duration is >48 hours or unknown and the patient is stable, elective cardioversion generally requires either adequate prior anticoagulation or imaging, commonly TEE, to exclude atrial thrombus.
• In HFrEF, early rhythm control and catheter ablation merit cardiology review, particularly if AF is contributing to LV dysfunction or recurrent HF admissions.