A patient in their early 20s attends with an episode of palpitations and pre-syncope. They are normally fit and well and feel back to normal by the time they arrive in the Emergency Department. You are shown their ECG (above - click to enlarge).
A: Short PR interval.
B: Slurred upstroke of R wave (delta wave).
These are the ECG features known as the Wolff-Parkinson-White (WPW) pattern. WPW Syndrome, first described in 1930, describes the presence of the WPW pattern on ECG plus the clinical manifestation of symptomatic arrhythmias. This patient also has a right bundle branch block pattern in V1. WPW is caused by a congenital accessory pathway which 'bypasses' the normal cardiac conduction pathway and so is potentially arrhythmogenic.
This case gave me the opportunity to read again on WPW; a importance differential in cases of palpitations and syncope covered in the 'Collapse?Cause' and 'WOBBLER' Take Aurally podcasts.
- Remember the difference between the WPW pattern and WPW syndrome. In one study of 22,500 healthy aviation personnel the WPW pattern was seen in 0.25% with only 1.8% of them developing any arrhythmia(1). In another study of patients with known WPW pattern followed over 22 years the incidence of arrhythmia was 1% per year(2).
- There are actually two types of WPW Syndrome. In type A there is a positive delta wave in all chest leads as in this case. In type B there is a negative delta wave in leads V1-V2.
- There is a risk of sudden cardiac death due to ventricular fibrillation often caused initially by uncontrolled atrial fibrillation which deteriorates into VF. This risk is low thankfully; the incidence of VF arrest as the initial manifestation of WPW was reported as 1.16% in one study(3).
(1): THE WOLFF-PARKINSON-WHITE SYNDROME AS AN AVIATION RISK; SMITH RF; Circulation. 1964;29:672. AD PMID 14153940
(2): The natural history of Wolff-Parkinson-White syndrome in 228 military aviators: a long-term follow-up of 22 years; Fitzsimmons PJ, McWhirter PD, Peterson DW, Kruyer WB; Am Heart J. 2001;142(3):530.
(3): Aborted sudden death in the Wolff-Parkinson-White syndrome; Timmermans C, Smeets JL, Rodriguez LM, Vrouchos G, van den Dool A, Wellens HJ; Am J Cardiol. 1995;76(7):492.