What is the role of digoxin (digitalis glycoside) in the intensive care unit (ICU) for patients with atrial fibrillation or heart failure?

Digoxin in the ICU

Digoxin should NOT be used as primary therapy for acute decompensated heart failure in the ICU, but has a specific role for rate control in patients with rapid atrial fibrillation, particularly when beta-blockers cannot be immediately initiated. 1, 2

Primary Role: Rate Control in Atrial Fibrillation

In ICU patients with acute heart failure and rapid atrial fibrillation (heart rate ≥100 bpm), digoxin is indicated for initial ventricular rate control, especially when beta-blocker initiation is not immediately feasible. 2

• Target rate control when ventricular rate is >80 bpm at rest or >110-120 bpm during exercise 2, 3
• Digoxin works as an adjunctive agent—beta-blockers remain superior for rate control and provide mortality benefit that digoxin does not 1
• In patients with reduced ejection fraction (<40%) and atrial fibrillation, use digoxin in addition to or prior to beta-blocker initiation 2, 3

NOT for Acute Stabilization

The ACC/AHA explicitly states that digoxin is NOT indicated as primary therapy for stabilizing patients with acute exacerbation of heart failure symptoms, including fluid retention or hypotension. 1, 2

• ICU patients with acute decompensated heart failure should first receive appropriate acute treatment (typically intravenous diuretics, vasodilators, or inotropes) 1
• Digoxin may be initiated after stabilization as part of establishing a long-term treatment strategy 1, 2

Dosing in the ICU Setting

Start with 0.25 mg daily for adults with normal renal function, but reduce to 0.125 mg daily (or every other day) in elderly patients (>70 years), those with renal impairment, or low lean body mass. 1, 2, 3

• Loading doses are generally not required in stable patients but may be considered in acute settings 2
• Target serum concentration: 0.5-1.0 ng/mL (some guidelines specify 0.5-0.9 ng/mL) 1, 3
• Levels >2 ng/mL are associated with toxicity 4, 5
• Intravenous administration is preferable to intramuscular; avoid bolus administration 6

Critical Contraindications in ICU Patients

Do not use digoxin in patients with:

• Second- or third-degree heart block without a permanent pacemaker 1, 2, 3, 6
• Pre-excitation syndromes (Wolff-Parkinson-White)—digoxin can shorten the refractory period of the accessory pathway and precipitate ventricular fibrillation 2, 3
• Suspected sick sinus syndrome 2, 3
• Ventricular fibrillation 6
• Acute myocardial infarction with ongoing ischemia 4
• Myocarditis 6

Mandatory Monitoring in the ICU

Serial monitoring of serum electrolytes (especially potassium and magnesium) and renal function is mandatory, as digoxin causes arrhythmias particularly with hypokalemia. 2, 3

• Hypokalemia, hypomagnesemia, and hypothyroidism increase toxicity risk even at therapeutic digoxin levels 3, 5
• Recent evidence from 2024 shows that intravenous digoxin use in elderly patients with renal dysfunction or potassium disturbances was not associated with increased 30-day mortality 7
• However, this does not negate the need for careful monitoring—the narrow therapeutic index remains a concern 4

Drug Interactions Critical in ICU

Reduce digoxin dose by 50% when adding these commonly used ICU medications that increase digoxin levels: 2, 3

• Amiodarone
• Diltiazem or verapamil
• Certain antibiotics (clarithromycin, erythromycin)
• Quinidine
• Cyclosporine

Clinical Outcomes Relevant to ICU

• Digoxin reduces heart failure hospitalizations by 28% (NNT=13 over 3 years) but has no effect on mortality 2, 3, 4
• In patients with heart failure and atrial fibrillation, digoxin initiation was associated with lower risk of heart failure readmission without increased mortality 8
• The benefit applies to both HFrEF (ejection fraction ≤45%) and HFpEF (ejection fraction >45%) 8

Practical ICU Algorithm

1. Patient presents with acute decompensated heart failure + rapid atrial fibrillation:

   • First: Stabilize with IV diuretics, vasodilators, or other acute therapies 1
   • Second: Consider digoxin for rate control if beta-blocker cannot be started immediately 2
   • Third: Transition to beta-blocker as soon as clinically stable 1, 2, 3

2. Check contraindications before initiating:

   • ECG for heart block or pre-excitation 2, 3
   • Renal function, potassium, magnesium 2, 3
   • Current medications for interactions 2, 3

3. Dose selection:

   • Age >70, renal impairment, or low body weight: 0.125 mg daily 1, 3
   • Otherwise: 0.25 mg daily 1, 2

4. Monitor:

   • Daily electrolytes and renal function 2, 3
   • Check digoxin level early in therapy, target 0.5-0.9 ng/mL 1, 3
   • Watch for toxicity signs: nausea, visual disturbances, arrhythmias 6

Common Pitfalls to Avoid

• Do not use digoxin as first-line acute inotrope—it is not indicated for hemodynamic stabilization 1, 2
• Do not use high doses (>0.25 mg daily) for rate control—add beta-blocker or amiodarone instead 5
• Do not forget to adjust for renal function—digoxin is renally excreted and accumulates in renal impairment 6, 9
• Do not overlook drug interactions—many ICU medications increase digoxin levels 2, 3