Wolff-Parkinson-White Syndrome: Symptoms and Clinical Presentation
Primary Symptoms
Palpitations are the most common presenting symptom in WPW syndrome, representing episodes of tachyarrhythmias that occur in approximately 95% of symptomatic patients. 1
Cardinal Symptoms Requiring Immediate Evaluation
Syncope or near-syncope is particularly concerning as it may indicate rapid conduction over the accessory pathway with risk of sudden cardiac death, occurring in patients with shortest pre-excited RR intervals <250 ms during atrial fibrillation 1, 2
Palpitations represent the hallmark symptom, typically caused by atrioventricular reciprocating tachycardia (AVRT) which accounts for 95% of reentrant tachycardias in WPW patients 1, 2
Dizziness occurs during tachyarrhythmia episodes and may precede syncope, warranting urgent evaluation 1
Chest pain can develop during sustained tachycardia episodes due to increased myocardial oxygen demand 1
Shortness of breath indicates potential hemodynamic compromise during rapid ventricular rates 1
Fatigue is reported by patients, particularly during activities like driving where 57% of patients with supraventricular tachycardia experience episodes 2
Electrocardiographic Features
Delta wave is the defining ECG feature, characterized by slurring of the initial QRS upstroke due to ventricular pre-excitation via the accessory pathway 2
Short PR interval (<0.12 seconds) occurs due to rapid conduction through the accessory pathway bypassing the AV node 2, 3
Wide QRS complex results from fusion of pre-excited ventricular activation with normal AV nodal conduction, though this may not be present in every case 4
Pseudo-infarction pattern frequently mimics inferior myocardial infarction on ECG and should not be misinterpreted 4
Life-Threatening Complications
Sudden cardiac death carries an annual risk of 0.15-0.39% over 3-22 year follow-up in general WPW patients, but increases to 2.2% in symptomatic patients and approaches 4% lifetime risk in those with documented arrhythmias 5, 1, 2
Pre-excited atrial fibrillation is particularly dangerous when the shortest pre-excited RR interval is <250 ms, as this can degenerate into ventricular fibrillation 5, 1, 2
Ventricular fibrillation occurs in 0-2% of asymptomatic patients, predominantly in children, and represents the mechanism of sudden death in WPW 2
Tachycardia-induced cardiomyopathy can develop with frequent or incessant tachyarrhythmias, causing reduced left ventricular systolic performance due to anomalous depolarization 2, 3
High-Risk Features Predicting Sudden Death
Shortest pre-excited RR interval <250 ms during spontaneous or induced atrial fibrillation is the strongest predictor of life-threatening events 5, 1, 2
History of symptomatic tachycardia significantly increases sudden death risk 5, 1
Multiple accessory pathways are associated with higher risk of malignant arrhythmias 5, 1, 2
Posteroseptal pathway location carries increased risk compared to other locations 1
Ebstein's anomaly when present with WPW substantially increases risk 5, 2
Accessory pathway refractory period <240 ms indicates high-risk rapid conduction capability 1, 2
Asymptomatic Presentation
Approximately 50% of patients with WPW are asymptomatic at diagnosis, yet sudden death may be the first manifestation in about half of cardiac arrest cases 2
Incidental ECG finding of pre-excitation pattern occurs in 0.1-0.3% of the general population during routine screening 2, 3
Intermittent pre-excitation or abrupt loss during exercise testing indicates low-risk pathways with 90% positive predictive value for benign course 2
Treatment Approach
Definitive Treatment: Catheter Ablation
Catheter ablation of the accessory pathway is the first-line definitive treatment for all symptomatic WPW patients, with success rates exceeding 95% and should be performed in experienced centers. 1
Class I Indications for Ablation (Mandatory)
Symptomatic patients with documented arrhythmias require ablation as first-line therapy 1, 6
Patients resuscitated from sudden cardiac arrest due to atrial fibrillation with rapid conduction over the accessory pathway causing ventricular fibrillation need immediate referral for ablation 5
Documented atrial fibrillation with WPW mandates ablation to prevent sudden cardiac death 5, 1
Syncope due to rapid heart rate or short bypass tract refractory period requires ablation 1
High-risk professions (pilots, public transport drivers, competitive athletes) with overt but asymptomatic accessory pathway conduction should undergo ablation 5
Ablation Success and Complications
Primary success rate is 88-95%, with final success reaching 93-98.5% after repeat procedures if needed 1
Major complications occur in 0.1-0.9% of cases, including complete heart block (0.1%), right bundle branch block (0.9%), left bundle branch block (0.3%), pericardial effusion (0.2%), and pneumothorax (0.2%) 1
Long-term outcomes show no development of malignant atrial fibrillation or ventricular fibrillation over 8 years of follow-up after successful ablation 1
Arrhythmic event rates at 5 years are 7% in ablated patients versus 77% in non-ablated patients 2
Acute Management Algorithm
Hemodynamically Unstable Patients
Immediate direct-current cardioversion is mandatory (Class I) for any patient with pre-excited atrial fibrillation and hemodynamic instability to prevent ventricular fibrillation. 1, 7
- Reanimation equipment must be immediately available as WPW with rapid ventricular response carries high risk for ventricular fibrillation 7
Hemodynamically Stable Patients with Pre-excited AF (Wide QRS ≥120 ms)
Intravenous procainamide is first-line pharmacological therapy (Class I) to restore sinus rhythm in stable patients 1, 7
Intravenous ibutilide is an alternative first-line agent (Class I) for stable patients 1, 7
Alternative medications (Class IIb) include intravenous quinidine, disopyramide, or amiodarone for stable patients with pre-excitation 7
Regular Supraventricular Tachycardia (Narrow QRS)
Adenosine can be used only when QRS is narrow (<120 ms) during tachycardia, indicating anterograde conduction through the AV node 7, 4
Propranolol is the drug of choice for regular supraventricular (reciprocating) tachycardia with narrow QRS complexes 4
Critical Medication Contraindications
AV nodal blocking agents are absolutely contraindicated in pre-excited atrial fibrillation as they can accelerate conduction through the accessory pathway and precipitate ventricular fibrillation. 1
Contraindicated Medications (Class III)
Beta-blockers (including metoprolol) can worsen outcomes by potentially accelerating conduction through the accessory pathway during atrial fibrillation 1
Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) are contraindicated as they slow AV nodal conduction but not the accessory pathway 1, 7
Digoxin is contraindicated due to its ability to enhance conduction through the accessory pathway 1, 7
Adenosine is contraindicated when QRS is wide (≥120 ms), indicating pre-excited conduction 1, 7
Intravenous amiodarone should be avoided in acute pre-excited atrial fibrillation despite being acceptable for chronic management 1
Management of Asymptomatic Patients
Observation without further testing is reasonable (Class IIa) for truly asymptomatic patients with pre-excitation pattern, as most adults have a benign course 2
Electrophysiological study for risk stratification is also reasonable (Class IIa) in asymptomatic patients to identify high-risk features: shortest pre-excited RR interval <250 ms during AF, accessory pathway refractory period <240 ms, multiple pathways, or inducible sustained AVRT 2
Catheter ablation should be considered (Class IIa) for asymptomatic patients with high-risk features after full explanation and careful counseling 5, 2
Common Pitfalls to Avoid
Never administer AV nodal blockers during wide-complex tachycardia in WPW, as this can be fatal 1, 7
Do not mistake pseudo-infarction pattern for true myocardial infarction on ECG 4
Recognize that left lateral accessory pathways may show minimal delta waves due to fusion with normal AV nodal conduction, potentially appearing as intermittent pre-excitation 2
Post-ablation monitoring remains necessary as ablation does not always prevent atrial fibrillation, especially in older patients, and additional therapy may be required 1
Short PR interval alone without delta waves does not constitute WPW syndrome and may represent normal variant conduction 2