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Management of Wolff-Parkinson-White syndrome

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Management of Wolff-Parkinson-White syndrome

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                       Wolff-Parkinson-White syndrome

Wolff-Parkinson-White (WPW) syndrome is an electrical disorder caused
by the presence of an accessory pathway which directly connects the atria
and ventricles and bypasses the atrio-ventricular node. Characteristically,
the 12-lead ECG shows a short PR interval and a slurred upstroke, termed
a delta wave to the QRS complex. Patients are at risk of supraventricular
arrhythmias including atrial fibrillation, atrial flutter and atrio-ventricular
re-entrant tachycardia (AVRT). Occasionally, patients with atrial
fibrillation or flutter may develop ventricular fibrillation and die
suddenly. However, the annual mortality from WPW is low with
maximal figures of 0.4% per annum. The prevalence is 1.5/1000.
Approximately 4% of patients have a familial form of the disorder.

Management:

Acute management

Atrial fibrillation:

DC cardioversion to restore sinus rhythm immediately if the patient is
haemodynamically embarrassed.

Class 1C or class III anti-arrhythmic agents to slow ventricular response
or restore sinus rhythm in patients who are haemodynamically stable.

NOTE: Digoxin, verapamil and adenosine are contra-indicated in the
management of pre-excited AF.

Anticoagulate if patient in AF > 48 hours or perform TOE to exclude
thrombus in left atrial appendage before attempting elective DC
cardioversion.

Atrioventriuclar re-entrant tachycardia (AVRT):

Manage as above. Vagal manoeuvres should be attempted before
considering further therapy.

Anticoagulation is not required.

NOTE: AV nodal blocking drugs such as digoxin, verapamil and
adenosine should be avoided in patients with wide QRS complexes as
these may be indicative of an antidromic AVRT. Generally, these drugs


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may be used in patients with orthodromic AVRT (narrow QRS
complexes on the ECG).

Chronic management

Pharmacological treatments with anti-arrhythmic drugs and
electrophysiological radiofrequency ablation of the accessory pathway
are the therapies available for the management of WPW syndrome.

High-risk patients should be treated with radiofrequency ablation of the
accessory pathway (table 1).

Symptomatic patients other than those mentioned in table 1 may also be
at risk of sudden death.             These patients should be offered
electrophysiological studies for risk stratification purposes. Patients with
easily inducible atrial fibrillation with RR intervals < 250 msec or those
with a short (< 270 msec) antegrade refractory period of the accessory
pathway and those with multiple accessory pathways should have
accessory pathway ablation (table 2). Patients who do not fulfil
electrophysiological high-risk criteria may be treated with class IC (and
to a lesser extent class 1A) and class III anti-arrhythmic drugs. Both
digoxin and verapamil are contra-indicated in the management of
antidromic AVRT in WPW syndrome.

Completely asymptomatic patients who are non-athletic and not in high
risk professions were previously considered to be at a low risk of sudden
death and were reassured without further investigation. However, recent
reports indicate that some completely asymptomatic patients may die
suddenly. Since almost all sudden deaths from WPW syndrome occur in
patients less than 40 years, it would be reasonable to offer
electrophysiological risk stratification studies to all patients < 40 years
with the WPW pattern before providing reassurance.

Population screening for WPW syndrome is not cost-effective but given
the fact the condition may be familial, first-degree relatives of affected
individuals should be invited to have a 12-lead ECG.




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Table 1 High risk patients with WPW syndrome

Survivors of sudden cardiac death due to ventricular fibrillation in
conjunction with ECG evidence of WPW pattern

Atrial fibrillation with rapid ventricular rates (RR intervals < 250msec)

Syncope

Family history of sudden death

WPW associated with Ebstein’s anomaly

Athletes and high-risk professions (eg pilots)


Table 2: Electrophysiological features of high-risk patients with
WPW


Easily inducible AF with RR interval < 250 msec

Accessory pathway with a short (<270 msec) antegrade refractory
pathway

Multiple accessory pathways




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