What are the contraindications for digoxin?

Digoxin Contraindications

Digoxin is absolutely contraindicated in patients with ventricular fibrillation, second- or third-degree atrioventricular block without a permanent pacemaker, pre-excitation syndromes (such as Wolff-Parkinson-White syndrome with atrial fibrillation), and known hypersensitivity to digoxin or other digitalis preparations. 1, 2, 3

Absolute Contraindications

Cardiac Conduction Disorders

• Second- or third-degree heart block without a permanent pacemaker is an absolute contraindication because digoxin further depresses AV nodal conduction and can precipitate complete heart block or asystole. 2, 3, 4
• Patients with suspected sick sinus syndrome should be approached with extreme caution, as digoxin can worsen sinus node dysfunction. 2

Pre-Excitation Syndromes

• Wolff-Parkinson-White syndrome and other pre-excitation syndromes represent absolute contraindications, particularly when atrial fibrillation or atrial flutter is present, because digoxin can shorten the refractory period of the accessory pathway and precipitate ventricular fibrillation. 2, 3, 4

Hypersensitivity

• Known hypersensitivity to digoxin or any digitalis preparation is an absolute contraindication. 1
• Previous evidence of digoxin intolerance constitutes a contraindication to reinitiating therapy. 2, 3

Life-Threatening Arrhythmias

• Ventricular fibrillation is an absolute contraindication per FDA labeling. 1

Relative Contraindications and High-Risk Scenarios

Electrolyte Disturbances

• Uncorrected hypokalemia, hypomagnesemia, or hypercalcemia dramatically increase the risk of digoxin toxicity even at therapeutic serum concentrations, because these electrolyte abnormalities sensitize the myocardium to digoxin's effects. 3, 5, 4
• Serum potassium should be maintained between 4.0–5.5 mEq/L before initiating digoxin. 3, 5

Metabolic and Endocrine Disorders

• Hypothyroidism increases sensitivity to digoxin and lowers dosing requirements, raising toxicity risk. 3, 5
• Severe renal impairment (creatinine clearance < 30 mL/min) requires extreme caution, as digoxin is primarily renally excreted and accumulation is inevitable without dose reduction. 3, 4

Acute Cardiac Conditions

• Acute myocardial infarction represents a relative contraindication due to increased myocardial irritability. 3
• Decompensated heart failure with hemodynamic instability or cardiogenic shock should prompt consideration of alternative therapies, as digoxin is not indicated for acute stabilization. 3, 6

Drug Interactions Creating Contraindications

• Digoxin should be used with extreme caution or avoided when combined with other drugs that depress AV nodal function (amiodarone, beta-blockers, non-dihydropyridine calcium channel blockers) unless carefully monitored, as additive AV blockade can occur. 2, 3, 6

Common Clinical Pitfalls

• Do not assume "therapeutic" digoxin levels exclude toxicity—toxicity can occur at concentrations below 2 ng/mL when electrolyte abnormalities, renal dysfunction, hypothyroidism, or drug interactions coexist. 3, 5, 7
• Never administer digoxin to patients with hypokalemia (potassium < 4.0 mEq/L) without first correcting the deficiency, as this dramatically increases the risk of life-threatening arrhythmias. 3, 5
• Avoid loading doses in stable outpatients with heart failure or atrial fibrillation, as they provide no mortality or morbidity benefit and increase toxicity risk. 2, 3, 4
• Recognize that digoxin monotherapy is ineffective for rate control during exercise in atrial fibrillation due to its vagally-mediated mechanism; combination with a beta-blocker is required for adequate rate control. 2, 3, 4