What is the appropriate drug to control the rhythm in an 18-year-old female with Wolff‑Parkinson‑White syndrome presenting with atrial fibrillation and a rapid wide‑complex tachycardia?

Amiodarone (Option B) is the appropriate choice for rhythm control in this patient with WPW and atrial fibrillation presenting with wide-complex tachycardia.

However, the absolute priority is immediate electrical cardioversion if she shows any hemodynamic instability, followed by definitive catheter ablation of the accessory pathway.

Critical Understanding: Why AV Nodal Blockers Are Deadly

In WPW with atrial fibrillation, the wide QRS complex (≥120 ms) indicates pre-excited ventricular activation through the accessory pathway. Beta-blockers (A), digoxin (C), and verapamil (D) are absolutely contraindicated 1, 2, 3, 2, 4. These AV nodal blocking agents increase refractoriness of the AV node, which paradoxically encourages preferential conduction down the accessory pathway, accelerating the ventricular rate and potentially triggering ventricular fibrillation 2.

The Pharmacologic Approach for Stable Patients

Since this patient has a heart rate of 250 bpm with wide-complex tachycardia but the question asks about rhythm control (implying relative hemodynamic stability), the guideline-based approach is:

First-Line Pharmacologic Options (Class I Recommendations):

• Intravenous procainamide or ibutilide are the Class I recommendations for hemodynamically stable WPW patients with AF and wide QRS complexes 1, 2, 3, 4

Second-Line Option (Class IIb):

• Amiodarone is listed as a Class IIb recommendation - it may be administered to hemodynamically stable patients with AF involving conduction over an accessory pathway 1, 2, 3, 2

Why Amiodarone Among These Choices

Given the multiple-choice options provided (none include procainamide or ibutilide), amiodarone (B) is the only acceptable answer. While amiodarone carries theoretical risks in WPW-AF, including case reports of inducing ventricular fibrillation 5, 6, 7, more recent evidence suggests it can be used cautiously in selected stable patients 8.

The critical caveats for amiodarone use:

• Patient must be hemodynamically stable with relatively lower heart rates
• Loading dose of 150 mg IV preferred
• Requires continuous cardiac monitoring with defibrillator immediately available
• Should not be first-line when procainamide/ibutilide are available 6, 8

The Definitive Management Algorithm

1. If hemodynamically unstable (hypotension, chest pain, altered mental status): Immediate electrical cardioversion 1, 2, 3, 4

2. If hemodynamically stable with wide QRS ≥120 ms:

   • First choice: IV procainamide or ibutilide
   • Alternative (from your options): IV amiodarone with intensive monitoring
   • Never: Beta-blockers, calcium channel blockers, or digoxin

3. Definitive therapy: Catheter ablation of the accessory pathway is the Class I recommendation for all symptomatic WPW patients with AF, particularly with rapid rates or syncope 1, 2, 3, 4

Common Pitfall to Avoid

The most dangerous error is misinterpreting this wide-complex tachycardia as "just AF with rapid ventricular response" and reflexively administering standard rate-control agents (beta-blockers, calcium channel blockers, or digoxin). This can be lethal 2, 9, 2, 10. The wide QRS and extremely rapid rate (250 bpm) are the electrocardiographic clues that scream "pre-excited AF in WPW" - requiring completely different management.

Answer: B) Amiodarone (with the understanding that electrical cardioversion may be needed urgently, and catheter ablation is the definitive solution).