What is Digoxin used for?

What Digoxin Is Used For

Digoxin is primarily used for two indications: (1) controlling heart rate in patients with atrial fibrillation, particularly those with heart failure and reduced ejection fraction (LVEF <40%), and (2) reducing hospitalizations and improving symptoms in patients with heart failure with reduced ejection fraction (HFrEF) who remain symptomatic despite optimal medical therapy. 1, 2

Primary Indications

Heart Failure with Reduced Ejection Fraction (HFrEF)

• Digoxin reduces heart failure hospitalizations by 28% (NNT=13 over 3 years) in patients with symptomatic HFrEF (NYHA class II-IV) and LVEF <40%, though it has no effect on mortality. 1

• The drug improves symptoms, quality of life, exercise tolerance, and ventricular function when added to guideline-directed medical therapy (ACE inhibitors/ARBs, beta-blockers, and aldosterone antagonists). 1, 2

• Digoxin should be considered as adjunctive therapy in patients with persistent symptoms despite optimal doses of ACE inhibitors/ARBs, beta-blockers, and aldosterone antagonists—it works best as part of comprehensive heart failure therapy, not as monotherapy. 1

• These benefits occur regardless of underlying rhythm (sinus rhythm or atrial fibrillation). 1, 3

Atrial Fibrillation with Heart Rate Control

• In patients with atrial fibrillation and LVEF <40%, digoxin is recommended for heart rate control in addition to, or prior to, a beta-blocker (Class I recommendation). 1

• Digoxin is particularly useful for rate control in patients with a sedentary lifestyle or those who cannot tolerate beta-blockers or calcium channel blockers, as its vagotonic effect on the AV node is most effective at rest. 4, 5

• Target heart rate control: add digoxin if ventricular rate is >80 bpm at rest or >110-120 bpm during exercise despite beta-blocker therapy. 1

What Digoxin Is NOT Used For

• Digoxin is NOT indicated as primary therapy for acute decompensated heart failure or stabilization of patients with acute exacerbation of heart failure symptoms, including fluid retention or hypotension. 6, 3

• Such patients should first receive appropriate acute treatment (diuretics, vasodilators), and digoxin may be initiated after stabilization as part of long-term strategy. 6

Practical Dosing Strategy

• Start with 0.125 mg daily (or every other day) in elderly patients (>70 years), those with renal impairment, or low lean body mass. 1, 6

• Use 0.25 mg daily only in younger adults with normal renal function. 1

• Loading doses are not necessary in stable outpatients with chronic heart failure. 1, 3

• Target therapeutic serum concentration: 0.5-0.9 ng/mL (some guidelines cite 0.6-1.2 ng/mL, but lower levels minimize toxicity while maintaining efficacy). 1

Critical Contraindications

Do not use digoxin in patients with: 1, 6

• Second- or third-degree heart block without a permanent pacemaker
• Pre-excitation syndromes (Wolff-Parkinson-White syndrome)—digoxin can shorten the refractory period of the accessory pathway and induce ventricular fibrillation
• Suspected sick sinus syndrome (use extreme caution)
• Previous digoxin intolerance

Mandatory Monitoring

• Serial monitoring of serum electrolytes (especially potassium and magnesium) and renal function is mandatory, as digoxin causes arrhythmias particularly with hypokalemia. 1

• Check digoxin level early during chronic therapy, but routine serial measurements are not necessary once stable. 1

• Monitor for signs of toxicity: sinoatrial and AV block, atrial and ventricular arrhythmias, confusion, nausea, anorexia, and disturbance of color vision. 1

Important Drug Interactions

• Amiodarone, diltiazem, verapamil, certain antibiotics (clarithromycin, erythromycin), quinidine, itraconazole, and cyclosporine increase plasma digoxin levels—reduce digoxin dose by 50% if adding these agents. 1, 3

Clinical Context and Positioning

• Beta-blockers remain the preferred long-term treatment for rate control in atrial fibrillation and provide mortality benefit in heart failure, unlike digoxin. 1

• The magnitude of benefit from guideline-directed medical therapy (ACE inhibitors/ARBs, beta-blockers, aldosterone antagonists) far exceeds that of digoxin. 1

• Digoxin is the only oral inotrope that does not increase mortality in heart failure patients, particularly when low doses are used. 7