I45.6

Pre-excitation syndrome (I45.6): WPW, delta wave, tachycardias, dangerous pre-excited AF and catheter ablation.

Pre-excitation syndrome (ICD-10 I45.6) is a condition in which part of the ventricles is activated too early through an accessory pathway, an extra strip of conducting muscle between the atria and ventricles that bypasses the AV node. The best known form is Wolff–Parkinson–White (WPW) syndrome. On the ECG the PR interval is short and the QRS starts with a slurred upstroke, the delta wave. When pre-excitation is accompanied by episodes of tachycardia, it is called WPW syndrome; without symptoms it is called the WPW pattern. The accessory pathway can form a circuit for re-entrant tachycardia and, more rarely, conduct atrial fibrillation very fast to the ventricles.

ICD-10 I45.6WPWTachycardia

PR interval< 120 ms

QRSdelta wave, often widened

Typical arrhythmiaAV re-entrant tachycardia

Definitive treatmentcatheter ablation

Figure 1. Left: normal conduction. Right: pre-excitation — short PR interval and delta wave (slurred start of the QRS) because the ventricles are partly activated through the accessory pathway.

Symptoms

Many people with a WPW pattern never have symptoms. Others experience episodes of sudden, rapid regular palpitations that start and stop abruptly, sometimes with dizziness, breathlessness, chest discomfort or fainting. The most dangerous situation is atrial fibrillation with pre-excitation: impulses pass very rapidly through the accessory pathway and can degenerate into ventricular fibrillation and sudden death, though this is rare.

Diagnosis and treatment

ECG (delta wave), Holter or event monitoring; electrophysiological study to locate the pathway and assess its risk
Acute regular tachycardia: vagal manoeuvres, then adenosine; electrical cardioversion if the patient is unstable
Pre-excited AF: drugs that block the AV node (adenosine, beta-blockers, verapamil, diltiazem, digoxin) must be avoided because they can accelerate conduction through the pathway; electrical cardioversion is used if unstable
Catheter ablation of the accessory pathway is the treatment of choice for symptomatic patients and is curative in most

Call emergency services

for fast palpitations with fainting, chest pain, severe breathlessness or confusion.

References

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. doi:10.1093/eurheartj/ehz467
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. doi:10.1161/CIR.0000000000000311

This article is for general information and does not replace a consultation with a doctor. Diagnosis and treatment must be decided by a physician on the basis of symptoms, examination and tests.

Published on 23 March 2019