Syncope in the Wolff-Parkinson-White syndrome: incidence and electrophysiologic correlates

Syncope in the patient with Wolff-Parkinson-White (WPW) syndrome raises the specter of rapid tachyarrhythmias and the possibility of sudden cardiac death. We reviewed the records of 55 consecutive WPW patients referred for electrophysiologic evaluation of known or suspected arrhythmias to determine the incidence and significance of syncope. Twelve patients (22.6%) reported the occurrence of at least one episode of syncope. In eleven (20%) of these, syncope was preceded by rapid palpitations. Forty-three patients (77.4%) had no syncopal episodes. These two groups did not differ significantly with regard to age, sex, presence of associated cardiac or neurologic disease, drug history or accessory pathway location. There was no significant difference in cycle length of reciprocating tachycardia (syncope = 295.6 +/- 59.8 vs non-syncope = 334.5 +/- 59.6 ms, p less than .5), shortest R-R intervals between preexcited beats (260 +/- 78.6 vs 246.7 +/- 55.4 ms, p less than .5) and average R-R interval (364.4 +/- 37.9 vs 367.4 +/- 77.5 ms, p less than .5) measured during atrial fibrillation. The anterograde effective refractory period of the accessory pathway (292.1 +/- 31.9 vs 299 +/- 58.1 ms, p less than .5) and the shortest cycle length with 1:1 conduction over the accessory pathway (306.7 +/- 75 vs 289.1 +/- 77.5 ms, p less than .5) similarly did not differ. We conclude that syncope occurs in approximately 20% of patients with the Wolff-Parkinson-White syndrome referred for assessment of tachycardia. Patients with syncope do not have distinct clinical features or a more malignant electrophysiologic profile, suggesting that other extracardiac factors may play an important role in the genesis of syncope in this group.