Relation of syncope in young patients with Wolff-Parkinson-White syndrome to rapid ventricular response during atrial fibrillation

Syncope in patients due to Wolff-Parkinson-White (WPW) syndrome may be related either to a rapid rate of supraventricular tachycardia or to rapid ventricular response over the accessory pathway during atrial fibrillation (AF). From 1982 to 1987, 74 patients ≤25 years old (mean age 12.6 years) with WPW syndrome on electrocardiogram underwent electrophysiologic study. Of the 74 patients, 14 (19%) had a history of syncope. During electrophysiologic study 9 of 14 patients with syncope had sustained (>5 minutes or requiring termination due to hypotension) AF. Of the remaining 5 patients, 3 had inducible nonsustained AF and 2 had no AF. None of the 60 patients without syncope developed sustained AF; 34 had nonsustained and 26 had no AF. Occurrence of sustained AF had a sensitivity of 64% and specificity of 100% for history of syncope. All patients with syncope and AF (12) had a short RR interval between 2 consecutive preexcited QRS complexes during AF at ≤220 ms, in contrast to 9 of 34 patients without syncope (p <0.001, sensitivity 100%, specificity 74%). No patient with a short RR interval between 2 consecutive preexcited QRS complexes during AF of >220 ms had a history of syncope. Thus, in these young patients with WPW syndrome, occurrence of AF with a rapid ventricular response during electrophysiologic study correlated well with a history of syncope and may be the cause of syncope in most patients. Electrophysiologic study may be helpful in identification of young patients with WPW at risk for syncope.