A patient with atrial fibrillation and Wolff-Parkinson-White syndrome presents to the emergency department. Administration of which drug is most dangerous in this setting?
- A Procainamide
- B Verapamil ✓
- C Amiodarone
- D Flecainide
Correct answer: B. Verapamil
Explanation
In atrial fibrillation with WPW syndrome, the AV node normally limits ventricular rate by blocking some impulses. Verapamil (and digoxin) block AV nodal conduction, forcing more impulses down the accessory pathway (Bundle of Kent) which has a shorter refractory period, potentially accelerating the ventricular rate to 300+ bpm and precipitating ventricular fibrillation. Procainamide is actually preferred as it prolongs accessory pathway refractory period.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.