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 less than or equal to 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 (greater than 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 less than or equal to 220 ms, in contrast to 9 of 34 patients without syncope (p less than 0.001, sensitivity 100%, specificity 74%). No patient with a short RR interval between 2 consecutive preexcited QRS complexes during AF of greater than 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.