Wolff-Parkinson-White syndrome(WPW syndrome) is well known and somtimes causes life-threatening arrhythmias.To date,the clinical and electrophysiologic charicteristics of patients with WPW syndrome in Korea has not been available,though results of catheter ablation treatment for atrioventricular reentrant tachycardia(AVRT) including WPW syndrome were reported.

Clinical and electrocardiographic(ECG) characteristics and results of electrophysiologic study of consecutive 400 patients with WPW syndrome who underwent electrophsiologic study between December 1986 and September 1995 were analyzed.

Mean age of the patients was 35 years and male patients were more common(262male patients,65.5%).Mean duration and frequency of palpitation episodes were 8.1 years and 4.2 times per month,respectively.Thirty six patients(9.0%) experienced syncopal episodes and the half of them were associated with atrial fibrillation.Two cases of aborted sudden cardiac death were associated with atrial fibrillation.Twenty four cases of congenital heart diseases and 13 cases of acquired heart diseases were found.The most commonly associated cardiac disease was Ebstein's anomaly(8 cases,2,0%).Clinically,368 patients(92,0%) had ECG-documented tachycardias and 46 patients had two or more types of tachycardia.Orthodromic AVRT was the most common tachcardia (227 patients including 44 cases with coexisting atrial fibrillation).Atrial fibrillation was documented in 115 patients(31.1%) and antidromic AVRT in 23 patients(6.2%).Patients with antidromic AVRT were more likely to have multiple accessory pathways compared to those with orthodromic AVRT (30.4% versus 4.3%).On electrophysiologic study,the most commonly inducible tachcardia was also orthodromic AVRT (334/389 cases,89.8%).Antidromic AVRT was induced in 23 cases(6.0%).Atrial fibrillation was present in 104 patients(27.2%),especially in those with clinically documented atrial fibrillation(71.3% vs 12.3%).In 17 patients without inducible tachycardias,ventriculoatrial conduction was absent or had long effective refractory period.Finally,396 patients(99.0%) had clinically documented or inducible tachycardias.Eight patients with Ebstein's anomaly had right-sided accessory pathway(87.5%)exept one case.Twenty four patients had secondary accessory pathway.The most common site of accessory pathway including secondary accessory pathway was left free wall(204 cases,48.1%).Other accessory pathways were found at right free wall(123 cases,29.0%),posteroseptal(54 cases,17.5%)and anteroseptal site(15 cases,3.5%)in order.

The clinical and electrophysiologic characteristics of patients in this series were similar with those of previous reports of other countries.Because certain types of tachyarrhythmia were associated with characteristic electrophysiologic findings such as the relationships between antidromic AVRT and presence of secondary accessory pathways or clinical atrial fibrillation and higher occurrence rate of atrial fibrillation during electrophysiologic study,it is important to document clinical tachyarrhythmias with ECG.And electrophysiologic study can have important clinical implications in diagnosis and especially in curative treatment.