title: Longitudinal electrophysiologic assessment of asymptomatic patients with the Wolff-Parkinson-White electrocardiographic pattern.
abstract: Although most asymptomatic patients with the Wolff-Parkinson-White electrocardiographic pattern have a good prognosis, some die suddenly. The mechanism of sudden death is usually ventricular fibrillation, which is triggered by atrial fibrillation with a rapid ventricular response rate. Electrophysiologic testing has been proposed to identify asymptomatic patients who may be at risk for sudden death. Meaningful application of such testing requires a knowledge of whether the electrophysiologic measurements are reproducible over time. Consequently, we performed electrophysiologic studies on two occasions at least 36 months apart (mean +/- SD, 54.7 +/- 14) in 29 asymptomatic patients with the pattern. Twenty-seven patients remained asymptomatic, and sustained supraventricular tachycardia developed in two during the follow-up period. Nine patients (31 percent) lost the capacity for preexcitation and anterograde conduction over the accessory pathway, which produces the Wolff-Parkinson-White pattern. The others had little change in measurements of conduction over the accessory pathway. Patients who lost conduction over the accessory pathway tended to be older (mean +/- SD, 50 +/- 18 vs. 39 +/- 11 years; P = 0.06) than patients who retained preexcitation, and they had longer anterograde effective refractory periods at the first assessment (414 +/- 158 vs. 295 +/- 27 msec; P = 0.003). We conclude that a considerable number of asymptomatic patients with the Wolff-Parkinson-White pattern lose their capacity for anterograde conduction over the accessory pathway. This loss of capacity probably contributes to the low mortality among asymptomatic patients.
authors.affiliation: Clinical Electrophysiology Laboratory, University Hospital, London, ON, Canada.
authors.forename: G J
authors.initials: GJ
authors.lastname: Klein
authors.forename: R
authors.initials: R
authors.lastname: Yee
authors.forename: A D
authors.initials: AD
authors.lastname: Sharma
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012032:Refractory Period, Electrophysiological; D014693:Ventricular Fibrillation / Q000503:physiopathology; D014927:Wolff-Parkinson-White Syndrome / Q000503:physiopathology*