A 45-year-old woman presents with palpitations and syncope. ECG shows a short PR interval (0.1 sec), delta waves in V1-V4, and wide QRS. She has documented supraventricular tachycardia. Which treatment carries the highest risk of precipitating ventricular fibrillation in this patient?
- A Verapamil or diltiazem (AV nodal blocking agents) ✓
- B Adenosine for acute conversion
- C Flecainide
- D Radiofrequency catheter ablation
Correct answer: A. Verapamil or diltiazem (AV nodal blocking agents)
Explanation
This patient has Wolff-Parkinson-White (WPW) syndrome with pre-excitation. AV nodal blockers (verapamil, diltiazem, digoxin) are CONTRAINDICATED in WPW with AF as they block the AV node, forcing conduction entirely down the accessory pathway at rapid rates, potentially causing ventricular fibrillation. Adenosine can similarly precipitate AF during an SVT episode in WPW and should be used cautiously. Flecainide (or procainamide) can block the accessory pathway and is preferred in pre-excited AF. Catheter ablation is the definitive curative treatment.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.