What is the management of Wolf-Parkinson-White (WPW) syndrome?

Management of Wolff-Parkinson-White (WPW) Syndrome

Catheter ablation of the accessory pathway is the first-line definitive treatment for symptomatic WPW syndrome, with a success rate exceeding 95% and should be performed in experienced centers, particularly for patients with syncope, documented atrial fibrillation, or short bypass tract refractory periods. 1, 2

Risk Stratification

High-Risk Features Requiring Intervention

• History of symptomatic tachycardia (annual sudden cardiac death risk 2.2% vs 0.15-0.2% in asymptomatic patients) 2
• Short RR intervals (<250 ms) between pre-excited beats during atrial fibrillation 2, 3
• Multiple accessory pathways or posteroseptal location 2
• Syncope due to rapid heart rate 1, 2

Asymptomatic Patients

• Many remain asymptomatic throughout life, but approximately one-third will develop atrial fibrillation 2, 4
• Adolescents are at particular risk for developing atrial fibrillation that can degenerate into ventricular fibrillation 2

Acute Management Algorithm

Hemodynamically Unstable Patients (Class I Recommendation)

Immediate direct-current cardioversion is mandatory to prevent ventricular fibrillation 1, 2, 3, 5

• Have resuscitation equipment immediately available due to high risk of ventricular fibrillation 3
• Do not delay for pharmacological attempts 3

Hemodynamically Stable Patients with Pre-Excited AF (Wide QRS ≥120 ms)

First-line pharmacological therapy (Class I):

• Intravenous procainamide OR intravenous ibutilide to restore sinus rhythm 1, 2, 3, 5
• These agents block conduction through the accessory pathway directly 5

Alternative agents (Class IIb):

• Intravenous quinidine, disopyramide, or amiodarone (use amiodarone with extreme caution as it can paradoxically accelerate ventricular conduction) 1, 5

Regular Supraventricular Tachycardia (Narrow QRS)

• Adenosine can be used only if QRS is narrow (<120 ms), indicating anterograde conduction through the AV node 3
• Propranolol or digitalis are effective for narrow complex reciprocating tachycardia 6

Critical Medication Contraindications (Class III)

NEVER administer the following in pre-excited atrial fibrillation (can precipitate ventricular fibrillation):

• Beta-blockers (including metoprolol) 1, 2, 5
• Calcium channel blockers (diltiazem, verapamil) 1, 2, 3, 5
• Digoxin 1, 2, 3, 5
• Adenosine (when QRS is wide) 2, 3

Mechanism of harm: These AV nodal blocking agents prolong AV nodal refractoriness without affecting the accessory pathway, thereby favoring rapid conduction down the accessory pathway and potentially triggering ventricular fibrillation 2, 3, 5

Definitive Treatment: Catheter Ablation

Indications (Class I)

• All symptomatic patients with documented arrhythmias 1, 2
• Patients with atrial fibrillation and WPW 2, 5
• Syncope due to rapid heart rate 1, 2
• Short bypass tract refractory period 1, 2

Success Rates and Complications

• Primary success rate: 88-95%; final success after repeat procedures: 93-98.5% 2
• Permanent AV block risk: <1-2% in experienced centers 2
• Other complications: right bundle branch block (0.9%), left bundle branch block (0.3%), pericardial effusion (0.2%), pneumothorax (0.2%) 2
• No malignant arrhythmias over 8 years follow-up after successful ablation 2

Advantages Over Medical Therapy

• Avoids lifelong antiarrhythmic drug therapy 2
• Eliminates risk of sudden cardiac death from pre-excited atrial fibrillation 2, 5
• Particularly beneficial in adolescents and young adults 2

Important Clinical Pitfalls

Wide Complex Irregular Tachycardia

Assume pre-excited atrial fibrillation until proven otherwise and treat with procainamide or ibutilide, NOT AV nodal blockers 5

• The irregular rhythm indicates chaotic atrial activity with variable ventricular response through the accessory pathway 5
• This presentation carries high risk of degenerating into ventricular fibrillation if managed incorrectly 5

Post-Ablation Monitoring

• Ablation does not always prevent atrial fibrillation, especially in older patients 2
• Additional therapy may be required for atrial fibrillation management after successful accessory pathway ablation 2

ECG Mimicry

• WPW can mimic inferior myocardial infarction on ECG due to delta wave morphology 6
• Recognition of delta wave is the most important diagnostic criterion 6

Long-Term Medical Management (When Ablation Not Performed)

For patients who decline or are not candidates for ablation:

• Propafenone (Class IC agent) reduces conduction and increases effective refractory period of accessory pathway in both directions 7
• Flecainide, propafenone, or amiodarone prolong accessory pathway refractory periods and prevent rapid anterograde conduction during atrial arrhythmias 8
• Avoid AV nodal blocking agents as monotherapy 1, 2