What is the management of electrocardiogram (ECG) changes indicating digoxin toxicity?

From the Guidelines

Management of ECG changes indicating digoxin toxicity requires immediate discontinuation of digoxin and close cardiac monitoring, with administration of digoxin-specific antibody fragments (Digibind or DigiFab) for significant toxicity, as recommended by the 2023 American Heart Association focused update 1.

Key Considerations

• Discontinuation of digoxin and close cardiac monitoring are essential for managing ECG changes indicating digoxin toxicity.
• Digoxin-specific antibody fragments (Digibind or DigiFab) should be administered for significant toxicity, with dosing based on the amount of digoxin ingested or serum levels.
• Electrolyte abnormalities, particularly hypokalemia, hypomagnesemia, and hypercalcemia, must be corrected as they can worsen toxicity.
• Bradyarrhythmias may require temporary pacing, while ventricular arrhythmias can be treated with lidocaine or phenytoin.
• Magnesium sulfate (1-2g IV) can be useful for ventricular arrhythmias.
• Avoid calcium channel blockers and electrical cardioversion as they may precipitate ventricular fibrillation in digoxin toxicity.

Treatment Approach

• The treatment approach should be based on the severity of the toxicity, with mild cases requiring discontinuation of the medication, monitoring of rhythm, and maintenance of normal serum potassium 1.
• For more severe intoxication, digoxin-specific Fab antibody is the treatment of choice, with a rapid response rate and high survival rate in patients presenting with cardiac arrest 1.
• The use of digoxin-specific antibody fragments is supported by the 2023 American Heart Association focused update, which recommends their administration for digoxin or digitoxin poisoning 1.

Monitoring and Follow-up

• Serial ECGs and digoxin levels should be monitored until clinical improvement occurs.
• Patients with hyperkalemia or arrhythmias in the setting of digoxin serum levels of >2 mcg/L are at increased risk of death, and signs and symptoms of toxicity can manifest at lower serum levels 1.
• The use of digoxin-specific antibody fragments can lead to adverse events, including worsening of the underlying disease and hypokalemia, and potassium levels should be monitored 1.

From the FDA Drug Label

OVERDOSAGE Digoxin should be temporarily discontinued until the adverse reaction resolves. If the rhythm disturbance is a symptomatic bradyarrhythmia or heart block, consideration should be given to the reversal of toxicity with DIGIBIND® [Digoxin Immune Fab (Ovine)] If the rhythm disturbance is a ventricular arrhythmia, consideration should be given to the correction of electrolyte disorders, particularly if hypokalemia or hypomagnesemia is present DIGIBIND is a specific antidote for digoxin and may be used to reverse potentially life-threatening ventricular arrhythmias due to digoxin overdosage.

The management of ECG changes indicating digoxin toxicity includes:

• Temporary discontinuation of digoxin until the adverse reaction resolves
• Correction of electrolyte disorders, such as hypokalemia or hypomagnesemia
• Reversal of toxicity with DIGIBIND for symptomatic bradyarrhythmia, heart block, or ventricular arrhythmias
• Administration of potassium may be necessary, but with caution and monitoring for potassium toxicity 2 Key considerations include:
• Monitoring of the electrocardiogram for evidence of potassium toxicity or improvement in the arrhythmia
• Avoidance of potassium supplements in the setting of massive intoxication due to the risk of hyperkalemia 2

From the Research

ECG Changes Indicating Digoxin Toxicity

• Digoxin toxicity can manifest as various electrocardiogram (ECG) changes, including arrhythmias such as junctional tachycardia and ectopic atrial tachycardia 3
• The management of ECG changes indicating digoxin toxicity involves the use of digoxin-specific antibody fragments (digoxin-Fab) 4
• Digoxin-Fab is widely regarded as a safe and effective treatment for the management of acute and chronic digoxin poisoning 4

Indications for Digoxin-Fab

• Patients who have life-threatening tachy-bradyarrhythmias, hyperkalaemia (> 6 mmol/L) or haemodynamic instability with an elevated digoxin concentration (> 2 μg/L or 2.6 nmol/L) should be treated with digoxin-Fab 4
• The use of digoxin-Fab is also recommended in patients with normal digoxin and potassium levels, but with severe hypomagnesemia, as magnesium can precipitate digoxin-induced dysrhythmia 3

Prognostic Utility of Serum Potassium

• Elevated serum potassium is associated with fatality in patients with chronic digoxin toxicity 5
• The combination of bradycardia and hyperkalemia strongly predicts fatality even in cases with appropriate Fab administration 5

Treatment Regimen

• The treatment regimen for digoxin toxicity involves the use of digoxin-Fab, with the dose depending on the severity of the toxicity and the patient's clinical parameters 4, 6
• A systematic review of published literature on digoxin toxicity has developed consensus statements on diagnostic and therapeutic approaches, including the use of digoxin immune Fab for life-threatening exposure 7