Wolff–Parkinson–White Syndrome

Definition

Wolff–Parkinson–White (WPW) describes the presence of an accessory pathway — an additional electrical connection between the atria and the ventricles — that conducts impulses outside the normal atrioventricular node.^1,3

A distinction runs through everything that follows:

• WPW pattern — the characteristic ECG appearance in someone who has never had an arrhythmia.
• WPW syndrome — the same ECG in someone who has had episodes of tachycardia.^1,4

The distinction matters because the management differs, and because a great many people with the pattern will never develop the syndrome.^6,7 It was first described in 1930 in young, otherwise healthy people with a short PR interval and paroxysmal tachycardia.³

Pathophysiology

The delta wave

Because the accessory pathway lacks the deliberate delay built into the AV node, part of the ventricle is activated early — pre-excitation. On the ECG this produces a short PR interval and a slurred upstroke at the start of the QRS complex, the delta wave.^1,11

Re-entry tachycardia

With two connections between atria and ventricles, a circuit exists. An appropriately timed extra beat can set the impulse circling — down one route and back up the other — producing atrioventricular re-entrant tachycardia, typically 150–250 beats per minute with an abrupt start and stop.^1,2

The dangerous combination

The serious risk is different, and it is worth stating precisely. If atrial fibrillation develops, the atria fire chaotically at very high rates. The AV node protects the ventricles by filtering most of those impulses. An accessory pathway with rapid conduction does not filter, so the ventricles can be driven at extreme rates and may degenerate into ventricular fibrillation.⁸ This mechanism, described in 1979, is why WPW carries a small but genuine risk of sudden death, and why certain drugs used for atrial fibrillation are dangerous here.^1,8

Symptoms

• Palpitations — sudden, rapid, regular, starting and stopping abruptly. People often describe an exact moment of onset.¹
• Light-headedness during episodes.
• Chest discomfort or breathlessness with prolonged fast rhythms.
• Fainting, which is less common and warrants urgent assessment.^1,4
• No symptoms at all in a substantial proportion, the ECG being found incidentally.^6,7

Episodes often begin in adolescence or early adulthood, and are commonly mistaken for anxiety or panic — an abrupt onset and offset, and a rate too fast to count, distinguish them.¹

Diagnosis

• The resting 12-lead ECG, showing short PR, delta wave and widened QRS. Pre-excitation can be intermittent, so a normal ECG does not exclude it.^1,11
• Ambulatory monitoring to capture episodes and to look for intermittent pre-excitation, which suggests a pathway less able to conduct rapidly.^4,6
• Exercise testing, where abrupt loss of pre-excitation at higher heart rates is a reassuring finding.⁴
• Electrophysiology study, the definitive assessment. It locates the pathway and measures how fast it can conduct, which is the property that determines risk, and it is usually combined with ablation in the same procedure.^1,5

Management

• Acute termination of an episode — vagal manoeuvres first, then intravenous adenosine in hospital.^1,2
• Catheter ablation, the definitive treatment. A catheter destroys the accessory pathway, with success rates above 90–95% in experienced hands and a low complication rate; it is recommended for symptomatic patients and offered to many asymptomatic ones after risk assessment.^1,5,9
• Medication where ablation is declined or unsuitable.^1,2
• Risk stratification in asymptomatic pre-excitation, which is where most of the clinical debate sits.^4,6,7
• Advice on sport, since competitive athletes with pre-excitation are usually assessed and frequently offered ablation to remove the question altogether.¹⁰

A specific warning: certain drugs that block the AV node — including verapamil, diltiazem and digoxin — can be dangerous in atrial fibrillation with pre-excitation, because they push conduction down the accessory pathway.^1,2 Anyone with WPW should carry this information.

Co-morbidities and complications

• Atrial fibrillation, more common in WPW than in the general population of the same age, and the route to the most serious complication.^1,8
• Sudden cardiac death, estimated at roughly 0.1% per year in asymptomatic pre-excitation and lower still in those with intermittent pre-excitation.^6,12
• Ebstein's anomaly of the tricuspid valve, associated with accessory pathways, sometimes multiple.¹
• Anxiety and activity avoidance, common while episodes remain unpredictable and usually resolving after successful ablation.⁵

Medications

Prescribing sits with the cardiologist. Listed here so the reasoning is visible.

• Adenosine — used in hospital to terminate an episode, under monitoring.²
• Flecainide or propafenone — used to suppress episodes where ablation is not undertaken.¹
• Beta blockers — sometimes used, with the caveat above regarding pre-excited atrial fibrillation.^1,2
• Drugs to avoid — verapamil, diltiazem and digoxin in the setting of pre-excited atrial fibrillation.^1,2

Prognosis

For most people the outlook is excellent, and often curative — an unusual word in cardiology. Successful ablation removes the pathway, and with it the arrhythmia and the associated risk; long-term registry follow-up supports durable freedom from recurrence.^5,9

Untreated, the risk of a life-threatening event is low but not zero, and is concentrated in those with pathways capable of very rapid conduction.^6,8,12 Prospective follow-up of asymptomatic children found that most remained event-free, with events clustering in a minority identifiable by electrophysiological testing.⁷

Living with it

Before treatment, three things matter: knowing how to perform a vagal manoeuvre, knowing when an episode warrants an ambulance, and carrying a note about the drugs to avoid.^1,2

After successful ablation most people return to entirely normal activity, including competitive sport, once the cardiologist confirms the pathway is gone.¹⁰

Role of the physiotherapist

WPW is not a physiotherapy condition, and it would be dishonest to present it as one. Diagnosis, risk assessment and ablation are cardiology and electrophysiology work, and this page exists mainly so that people who have been given the diagnosis can understand it.

There are three situations in which we are genuinely useful:

• After successful ablation, when confidence has not caught up with the cure. People who have spent years avoiding exertion because it triggered episodes frequently remain deconditioned and wary long after the pathway is gone. Graded, supervised return to exercise is a straightforward physiotherapy task, and this is by far the commonest reason we see these patients.^5,10
• Where palpitations persist after ablation and cardiology has excluded recurrence. Breathing pattern disorder and anxiety-driven symptoms can mimic the original arrhythmia, and are treatable.
• Where an unrelated cardiorespiratory problem coexists, and we need to know the WPW history and its status before prescribing exertion.

We do not assess arrhythmia risk, advise on ablation, or clear anyone for competitive sport — those decisions belong with the cardiologist. If you have not yet been assessed and you are having episodes, that assessment comes first.

Part 1 · References

1. Brugada J, Katritsis DG, Arbelo E, et al. 2019 ESC Guidelines for the management of patients with supraventricular tachycardia. Eur Heart J 2020;41(5):655–720.
2. Page RL, Joglar JA, Caldwell MA, et al. 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia. Circulation 2016;133(14):e506–e574.
3. Wolff L, Parkinson J, White PD. Bundle-branch block with short P-R interval in healthy young people prone to paroxysmal tachycardia. Am Heart J 1930;5(6):685–704.
4. Cohen MI, Triedman JK, Cannon BC, et al. PACES/HRS expert consensus statement on the management of the asymptomatic young patient with a Wolff-Parkinson-White electrocardiographic pattern. Heart Rhythm 2012;9(6):1006–1024.
5. Pappone C, Vicedomini G, Manguso F, et al. Wolff-Parkinson-White syndrome in the era of catheter ablation: insights from a registry study of 2169 patients. Circulation 2014;130(10):811–819.
6. Obeyesekere MN, Leong-Sit P, Massel D, et al. Risk of arrhythmia and sudden death in patients with asymptomatic preexcitation: a meta-analysis. Circulation 2012;125(19):2308–2315.
7. Santinelli V, Radinovic A, Manguso F, et al. The natural history of asymptomatic ventricular pre-excitation: a long-term prospective follow-up study of 184 asymptomatic children. J Am Coll Cardiol 2009;53(3):275–280.
8. Klein GJ, Bashore TM, Sellers TD, et al. Ventricular fibrillation in the Wolff-Parkinson-White syndrome. N Engl J Med 1979;301(20):1080–1085.
9. Calkins H, Yong P, Miller JM, et al. Catheter ablation of accessory pathways, atrioventricular nodal reentrant tachycardia, and the atrioventricular junction. Circulation 1999;99(2):262–270.
10. Zipes DP, Link MS, Ackerman MJ, et al. Eligibility and disqualification recommendations for competitive athletes with cardiovascular abnormalities: Task Force 9 — arrhythmias and conduction defects. Circulation 2015;132(22):e315–e325.
11. Bhatia A, Sra J, Akhtar M. Preexcitation syndromes. Curr Probl Cardiol 2016;41(3):99–137.
12. Kim SS, Knight BP. Long term risk of Wolff-Parkinson-White pattern and syndrome. Trends Cardiovasc Med 2017;27(4):260–268.