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Management of Wolff-Parkinson-White syndrome
Sudden Cardiac Death 7 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 1 Sudden Cardiac Death 7 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. 2 Sudden Cardiac Death 7 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 3
"Management of Wolff-Parkinson-White syndrome"