Which single clinical scenario most clearly mandates administration of digoxin immune Fab rather than supportive correction alone?
- A Ventricular tachycardia with serum potassium 6.5 mEq/L after deliberate overdose ✓
- B Nausea and bradycardia with serum digoxin 1.8 ng/mL and potassium 4.2 mEq/L
- C Isolated ST depression on ECG with stable vitals
- D Asymptomatic bradycardia of 52 bpm in a patient on chronic digoxin
Correct answer: A. Ventricular tachycardia with serum potassium 6.5 mEq/L after deliberate overdose
Explanation
Life-threatening digoxin toxicity, defined as ventricular arrhythmias, severe bradyarrhythmias unresponsive to atropine, or serum potassium above 5.0 to 5.5 mEq/L in acute poisoning, requires digoxin-specific antibody fragments immediately. Hyperkalemia above 5 mEq/L in acute overdose predicts cardiac arrest and is itself an indication for Fab. Chronic toxicity with mild symptoms is managed by stopping digoxin and correcting electrolytes. Isolated ST changes reflect expected glycoside effect, not Fab indication.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
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