What is Wolff-Parkinson-White (WPW) syndrome?

From the Guidelines

Wolfe-Parkinson-White (WPW) syndrome is a heart condition characterized by an extra electrical pathway between the atria and ventricles, leading to episodes of rapid heartbeat (tachycardia), and is diagnosed by the presence of ventricular pre-excitation on the resting ECG, which participates in arrhythmias, as stated in the 2016 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.

Key Characteristics of WPW Syndrome

• The extra electrical pathway, also known as an accessory pathway, can cause the heart to beat too quickly, leading to symptoms such as palpitations, shortness of breath, and dizziness.
• The accessory pathway can be manifest or concealed, and can conduct in the anterograde or retrograde direction, as described in the 2016 ACC/AHA/HRS guideline 1.
• WPW syndrome can increase the risk of sudden cardiac death (SCD) due to the rapid conduction of atrial fibrillation (AF) to the ventricles, which can degenerate into ventricular fibrillation, as reported in the 2001 European Society of Cardiology task force on sudden cardiac death 1.

Risk Stratification and Management

• The risk of SCD in patients with WPW syndrome is estimated to be around 0.15-0.24% per year, and is higher in patients with a history of symptomatic tachycardia, multiple accessory pathways, and a shortest pre-excited R-R interval of <250 ms during AF, as stated in the 2016 ACC/AHA/HRS guideline 1.
• Catheter ablation is recommended in patients at risk of SCD, especially those who were resuscitated from ventricular fibrillation or had clinical atrial fibrillation with rapid ventricular responses, as recommended in the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1.
• Medications such as beta-blockers and calcium channel blockers can be used to control symptoms, but are not a substitute for catheter ablation in patients at high risk of complications.
• Patients with WPW syndrome should avoid triggers such as caffeine, alcohol, and stress, and should have regular follow-ups with a cardiologist to monitor their condition and adjust their treatment plan as needed.

Emergency Management

• In emergencies, vagal maneuvers or adenosine (6-12 mg IV rapid push) may be used to terminate episodes of tachycardia, as described in the example answer.
• However, in patients with WPW syndrome, adenosine should be used with caution, as it can worsen the condition by increasing the conduction through the accessory pathway, as reported in the 2013 management of patients with atrial fibrillation guideline 1.

From the Research

Definition and Pathophysiology

• Wolff-Parkinson-White (WPW) syndrome is a disorder characterized by the presence of at least one accessory pathway (AP) that can predispose people to atrial/ventricular tachyarrhythmias and even sudden cardiac death 2.
• WPW syndrome results from the congenital presence of impulse-conducting fascicles, known as accessory pathways (APs) or bypass tracts, which connect atria and ventricles across the annulus fibrosis and are capable of preexciting portions of the ventricular myocardium 3.

Clinical Features and Diagnosis

• WPW syndrome is the second most common cause of paroxysmal supraventricular tachycardia in most parts of the world, affecting about 0.1-0.3% of the general population 2.
• Most patients with WPW syndrome have normal anatomy, but it may be associated with concomitant congenital heart disease or systemic diseases 2.
• Although many individuals are asymptomatic, during supraventricular arrhythmia episodes, they may experience severe symptoms, including syncope or even sudden cardiac death (mainly due to pre-excited atrial fibrillation over rapidly conducting AP) 2.
• WPW syndrome is typically diagnosed through electrocardiography (ECG), and additional tests are necessary for risk assessment 2.

Treatment and Management

• Management of WPW syndrome may be quite challenging and can vary from only acknowledging the presence of the accessory pathway to pharmacological treatment or radiofrequency ablation 2.
• Medications that prolong AP refractory periods (flecainide, propafenone, and amiodarone) prevent rapid AP anterograde conduction (from atria to ventricles) in atrial tachycardias such as atrial fibrillation or flutter 3.
• Class IA or IC antiarrhythmic agents are used to slow AP conduction either with or without AV nodal blocking agents 3.
• Catheter delivered radiofrequency (RF) energy is now applied intravascularly to ablate APs, and RF ablation has become the initial nonpharmacological treatment of choice for WPW syndrome 3.
• Surgical ablation of a bypass tract in a symptomatic patient may be considered when RF ablation is not feasible 3, 4.