What is the treatment for Wolff-Parkinson-White (WPW) syndrome?

Treatment of Wolff-Parkinson-White (WPW) Syndrome

Catheter ablation of the accessory pathway is the definitive first-line treatment for symptomatic WPW syndrome, with success rates exceeding 95% and complication rates below 1-2% in experienced centers. 1, 2

Definitive Treatment: Catheter Ablation

Catheter ablation should be performed in all symptomatic patients with WPW syndrome, particularly those with:

• Documented arrhythmias (orthodromic or antidromic AVRT) 1, 2
• Syncope due to rapid heart rate 1, 2
• Documented atrial fibrillation with pre-excitation 1, 2
• Short accessory pathway refractory period (<250 ms) 1, 2, 3

The procedure achieves:

• Primary success rates of 88-95%, with final success reaching 93-98.5% after repeat procedures if needed 2
• Permanent AV block risk of <1-2% 1, 2
• Complete elimination of sudden cardiac death risk from pre-excited atrial fibrillation 2

Ablation is strongly preferred over lifelong antiarrhythmic therapy, especially in younger patients and athletes, as it avoids medication side effects and provides definitive cure. 1, 2

Acute Management of Arrhythmias in WPW

Hemodynamically Unstable Patients

Immediate direct-current cardioversion is mandatory when patients present with:

• Rapid ventricular response causing hypotension 1, 2
• Signs of hemodynamic compromise 1, 3
• Risk of deterioration to ventricular fibrillation 1, 2

This is a Class I recommendation with Level of Evidence B. 1

Hemodynamically Stable Patients with Pre-excited Atrial Fibrillation

For stable patients with wide QRS complexes (≥120 ms), administer intravenous procainamide or ibutilide to restore sinus rhythm. 1, 4, 2 This is a Class I recommendation. 1

Alternative agents (Class IIb recommendation):

• Intravenous quinidine 1, 4
• Intravenous disopyramide 1, 4
• Intravenous amiodarone 1, 4

Narrow Complex Tachycardia (Orthodromic AVRT)

When QRS duration is <120 ms during tachycardia, indicating antegrade conduction through the AV node:

• Intravenous adenosine may be used safely 1, 3
• Standard AV nodal blocking agents can be considered 1

Critical Contraindications: What NOT to Use

Never administer AV nodal blocking agents in patients with WPW and pre-excited atrial fibrillation (Class III recommendation, Level of Evidence B). 1, 2

Specifically contraindicated medications include:

• Beta-blockers (metoprolol, propranolol, esmolol) - can accelerate accessory pathway conduction and precipitate ventricular fibrillation 1, 2
• Calcium channel blockers (diltiazem, verapamil) - same mechanism of harm 1, 2
• Digoxin - enhances accessory pathway conduction 1, 2
• Adenosine (when QRS is wide ≥120 ms) - indicates pre-excitation where adenosine is dangerous 1, 3
• Lidocaine - ineffective and potentially harmful 1

These agents block the AV node but do not affect the accessory pathway, potentially causing preferential conduction down the accessory pathway during atrial fibrillation, leading to extremely rapid ventricular rates and ventricular fibrillation. 1, 2

Pharmacological Management (Temporary Bridge to Ablation)

While medications can be used acutely or as a bridge to ablation, they are not recommended as long-term definitive therapy. 1, 5

Acceptable antiarrhythmic agents that prolong accessory pathway refractoriness:

• Flecainide (Class IC) 6, 7
• Propafenone (Class IC) - reduces conduction and increases effective refractory period of the accessory pathway in both directions 6, 7
• Amiodarone 1, 7

These medications are used primarily for symptom control until definitive ablation can be performed. 5

Management of Asymptomatic WPW Pattern

Asymptomatic patients with WPW pattern on ECG require risk stratification before deciding on ablation. 8, 9

Consider invasive electrophysiological study and possible ablation for:

• Patients in high-risk occupations (pilots, professional athletes, commercial drivers) 8
• Those with inducible arrhythmias during electrophysiology study 8
• Patients with short accessory pathway refractory periods (<250 ms) identified non-invasively 2, 3

The risk-benefit calculation involves trading a very small risk of sudden death (0.15-0.2% annually in general WPW population, 2.2% in symptomatic patients) against a small procedural risk. 1, 2, 8

Special Populations

Athletes and Adolescents

Catheter ablation is particularly indicated in young athletes with WPW because:

• One-third of WPW patients develop atrial fibrillation, which can degenerate to ventricular fibrillation during exercise 1, 2
• Ablation avoids lifelong activity restrictions 1
• Success rates exceed 95% with minimal complications 1, 2

Pregnant Patients

While rare, WPW-related arrhythmias during pregnancy require careful management:

• Hemodynamic stability is critical for both mother and fetus 1
• Immediate cardioversion if unstable 1
• Avoid teratogenic antiarrhythmics when possible 1

Common Pitfalls to Avoid

1. Never assume narrow complex tachycardia is safe - verify QRS duration before administering adenosine or AV nodal blockers 1, 3

2. Do not delay cardioversion in unstable patients - attempting pharmacological conversion wastes critical time 1, 3

3. Avoid empiric beta-blocker or calcium channel blocker therapy without confirming the rhythm and QRS morphology 1, 2

4. Do not rely on antiarrhythmic drugs as definitive therapy - they have limited long-term efficacy and do not eliminate sudden death risk 1, 5

5. Post-ablation monitoring is essential - ablation of the accessory pathway does not always prevent atrial fibrillation, especially in older patients 2