If Wolff-Parkinson-White syndrome is suspected in a patient with a wide complex tachycardia, which antiarrhythmic is preferred?

If Wolff-Parkinson-White syndrome is suspected in a patient with a wide complex tachycardia, which antiarrhythmic is preferred?

• A. Adenosine
• B. Amiodarone
• C. Procainamide
• D. Diltiazem

Answer: (C)

In Wolff-Parkinson-White with a wide complex tachycardia, the goal is to slow conduction through the accessory pathway rather than just the AV node. Procainamide is a class IA antiarrhythmic that blocks sodium channels and prolongs the refractory period, including in the accessory pathway. This suppresses the bypass tract’s ability to conduct impulses, helping terminate the reentrant tachycardia and prevent rapid ventricular rates. Adenosine and calcium channel blockers mainly slow the AV node. In the setting of WPW, this can paradoxically allow the ventricles to be driven by impulses through the accessory pathway, heightening the risk of dangerous rhythms. Amiodarone can be used in some settings but procainamide is the preferred first-line choice for stable preexcited tachycardia because it directly targets the pathway responsible for the tachycardia. If the patient is unstable, synchronized cardioversion is the next step.

In Wolff-Parkinson-White with a wide complex tachycardia, the goal is to slow conduction through the accessory pathway rather than just the AV node. Procainamide is a class IA antiarrhythmic that blocks sodium channels and prolongs the refractory period, including in the accessory pathway. This suppresses the bypass tract’s ability to conduct impulses, helping terminate the reentrant tachycardia and prevent rapid ventricular rates.

Adenosine and calcium channel blockers mainly slow the AV node. In the setting of WPW, this can paradoxically allow the ventricles to be driven by impulses through the accessory pathway, heightening the risk of dangerous rhythms. Amiodarone can be used in some settings but procainamide is the preferred first-line choice for stable preexcited tachycardia because it directly targets the pathway responsible for the tachycardia. If the patient is unstable, synchronized cardioversion is the next step.