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

Treatment of Wolff-Parkinson-White (WPW) Syndrome

Catheter ablation of the accessory pathway is the first-line definitive treatment for all symptomatic patients with WPW syndrome, with success rates exceeding 95% and complication rates under 2%. 1, 2, 3

Immediate Management: Critical First Step

Identify QRS Complex Width During Tachycardia

The width of the QRS complex determines whether the arrhythmia is life-threatening and dictates completely different treatment approaches: 2

• Narrow QRS (<120 ms): Indicates orthodromic AVRT (anterograde conduction through AV node) - the most common arrhythmia in WPW 2
• Wide QRS (≥120 ms): Indicates pre-excited atrial fibrillation or antidromic AVRT (anterograde conduction through accessory pathway) - carries risk of ventricular fibrillation 2

Acute Treatment Algorithm

For Narrow-Complex Tachycardia (Orthodromic AVRT)

1. Vagal maneuvers (Valsalva or carotid sinus massage) as first-line treatment, terminating up to 25% of cases 2
2. Adenosine 6 mg IV push as second-line treatment, terminating approximately 95% of orthodromic AVRT by blocking AV nodal conduction 2, 4
   • If no conversion in 1-2 minutes, give 12 mg IV push 4
   • Must have defibrillator immediately available due to risk of precipitating rapid atrial fibrillation 4

For Wide-Complex Tachycardia (Pre-Excited Atrial Fibrillation)

Hemodynamically unstable patients:

• Immediate direct-current cardioversion to prevent ventricular fibrillation 1, 3

Hemodynamically stable patients:

• IV procainamide or ibutilide to restore sinus rhythm or slow ventricular rate 1, 2, 3
• Alternative agents include IV quinidine, disopyramide, or amiodarone (Class IIb recommendation) 1

Absolutely Contraindicated Medications in Pre-Excited AF

Never administer the following in patients with WPW who have wide-complex tachycardia or pre-excited atrial fibrillation (Class III recommendation): 1

• Adenosine (can precipitate ventricular fibrillation by triggering rapid AF) 2, 3, 4
• Beta-blockers (metoprolol, propranolol, esmolol) 1, 3
• Digoxin 1, 3
• Nondihydropyridine calcium channel blockers (diltiazem, verapamil) 1, 3
• IV amiodarone 1, 3

These agents slow AV nodal conduction but not the accessory pathway, facilitating preferential conduction over the accessory pathway during AF, which accelerates the ventricular rate and can precipitate ventricular fibrillation. 1, 3

Definitive Management: Catheter Ablation

Catheter ablation is recommended as first-line definitive therapy for: 1, 2, 3

• All symptomatic patients with WPW syndrome 1, 3
• Patients with syncope due to rapid heart rate 1, 3
• Patients with short bypass tract refractory period (<250 ms) 1, 3
• Patients with documented atrial fibrillation 1, 3

Success rates and complications: 3

• Primary success rate: 88-95%, with final success rates of 93-98.5% after repeat procedures if needed 3
• Permanent AV block: <1-2% 3
• Other complications: right bundle branch block (0.9%), left bundle branch block (0.3%), pericardial effusion (0.2%), pneumothorax (0.2%) 3

Risk Stratification for Sudden Cardiac Death

High-risk features requiring urgent ablation: 1, 3

• Short RR intervals (<250 ms) between pre-excited beats during atrial fibrillation 1, 3
• History of symptomatic tachycardia or syncope 1, 3
• Multiple accessory pathways 1, 3
• Posteroseptally located pathways 3

The annual risk of sudden cardiac death is 2.2% in symptomatic WPW patients versus 0.15-0.2% in asymptomatic patients. 3

Long-Term Pharmacological Management (If Ablation Declined or Not Feasible)

For prevention of orthodromic AVRT: 5, 6

• Propranolol or other beta-blockers (only if patient does NOT have pre-excited AF) 5
• Digitalis (only if patient does NOT have pre-excited AF) 5

For prevention of pre-excited atrial fibrillation: 7, 6

• Flecainide, propafenone, or amiodarone (prolong accessory pathway refractory period) 7
• Class IA agents (quinidine, procainamide) 5

Critical Pitfalls to Avoid

1. Never use AV nodal blocking agents in wide-complex tachycardia or known pre-excited AF - this is the most common fatal error 1
2. Do not assume narrow-complex tachycardia is safe - adenosine can still trigger rapid AF in susceptible patients, so have defibrillator ready 4
3. Ablation does not always prevent future AF, especially in older patients, so continued monitoring may be necessary 1, 3
4. Approximately one-third of WPW patients develop atrial fibrillation, which can degenerate into ventricular fibrillation 3