The Many ECG Faces of Wolff-Parkinson-White Syndrome

BACKGROUND: Wolff-Parkinson-White (WPW) syndrome is rare and can predispose to tachyarrhythmias. This case illustrates the heterogeneous electrocardiographic (ECG) features of WPW syndrome. CASE SUMMARY: A 57-year-old woman was admitted with pneumonia and atrial fibrillation with rapid ventricular response (174 beats/min). Atrial fibrillation terminated after diltiazem infusion, and repeat ECG showed sinus rhythm with pre-excitation (delta waves and a short PR interval). Subsequently, she developed an irregular wide complex tachycardia consistent with atrial fibrillation with pre-excitation (WPW syndrome). Catheter ablation of the accessory pathway was successfully performed. DISCUSSION: Varying degrees of pre-excitation in WPW can occur depending on accessory pathway properties and location, which can confound the diagnosis of WPW. TAKE-HOME MESSAGES: WPW can present without classic features of pre-excitation on initial ECG; comprehensive serial ECG analysis is crucial to accurately diagnose WPW. Ventricular tachycardia should be considered in the differential diagnosis of WPW, as ECG cannot reliably differentiate between antidromic WPW and ventricular tachycardia.