Intermittent versus Persistent Wolff-Parkinson-White Syndrome in Children: Electrophysiologic Properties and Clinical Outcomes.

BACKGROUND: Intermittent Wolff-Parkinson-White (WPW) syndrome is considered to have a lower risk of sudden death. Fewer data exist regarding electrophysiologic (EP) characteristics and the natural history of intermittent WPW in children. METHODS: All patients with WPW age 1-18 years at a single institution (1996-2013) were reviewed. Patients with intermittent preexcitation were compared to those with loss of preexcitation on Holter/exercise testing and those with persistent preexcitation. High-risk accessory pathway (AP) was defined as AP effective refractory period (APERP), block cycle length, or shortest preexcited RR interval during atrial fibrillation ≤250 ms. RESULTS: A total of 295 patients were included: 226 (76.6%) persistent, 39 (13.2%) intermittent, and 30 (10.2%) loss of preexcitation Holter/exercise. There were no differences in symptoms between groups. Median interquartile range APERP was significantly longer in intermittent WPW (380 [320, 488] ms vs 320 [300, 350] ms persistent, 310 [290, 330] ms loss of preexcitation Holter/exercise; P = 0.0008). At baseline, there was no difference between groups in frequency of high-risk pathways. However, when isoproterenol values were included, high-risk pathways were more frequent among patients with loss of preexcitation on Holter/exercise (54% vs 16% persistent, 11% intermittent; P = 0.005). There was one death in a patient with loss of preexcitation on exercise testing, no EP study, and prior drug use. A second patient with persistent WPW and APERP 270 ms required resuscitation following a methadone overdose. CONCLUSION: Intermittent preexcitation in children does not connote a lower risk AP by EP criteria or reduced symptoms. The low number of pediatric WPW patients who develop preexcited atrial fibrillation or sudden death warrants larger studies to investigate these outcomes.

Radiofrequency ablation of accessory pathways in patients with the Wolff-Parkinson-White syndrome: the long-term mortality and risk of atrial fibrillation.

AIMS: To assess the long-term mortality and occurrence of post-ablation atrial fibrillation in patients undergoing a radiofrequency ablation for the Wolff-Parkinson-White (WPW) syndrome. METHODS AND RESULTS: A retrospective cohort study of patients (N = 362) subjected to radiofrequency ablation of the WPW syndrome at Aarhus University Hospital from 1990 to 2011. A comparison cohort (N = 3619) was generated from the Danish National Board of Health Central Population Registry. We found no significant difference in all-cause mortality when comparing the WPW group with the control group [hazard ratio (HR): 0.77 and confidence interval (CI): 0.47-1.25]. After radiofrequency ablation, the WPW group had a significantly higher risk of atrial fibrillation than the control group (HR: 4.77 and CI: 3.05-7.43). Atrial fibrillation prior to ablation (HR: 4.66 and CI: 2.09-10.41) and age over 50 years (HR: 9.79 and CI: 4.29-22.36) at the time of ablation were independent risk factors for post-ablation atrial fibrillation in the WPW group. CONCLUSION: Patients with radiofrequency ablation-treated WPW syndrome have a post-ablation mortality that is similar to the background population. The risk of atrial fibrillation remains high after radiofrequency ablation of the WPW syndrome.

The electrophysiological characteristics of accessory pathways in pediatric patients with intermittent preexcitation.

BACKGROUND: Accessory pathways (APs) with intermittent preexcitation (IPX) are thought to be of lower risk, but there are reports of IPX patients presenting with rapidly conducted atrial fibrillation. METHODS: Retrospective study performed on patients with preexcitation who underwent an electro-physiological study (EPS). IPX was defined as loss of the delta wave on electrocardiogram prior to EPS. Patients with IPX were compared with those with persistent preexcitation (PPX) or suppression of the delta wave on exercise test (IPX-ET). Congenital heart disease and prior ablations were excluded. RESULTS: Of 328 patients with preexcitation, 41 (12.5%) had IPX. Patients with IPX or PPX were similar in age (12.9 years vs 13.0 years, P = 0.8) and AP location (left-sided 54% vs 50%, P = 0.7; septal 32% vs 35%, P = 0.4). Testing on isoproterenol was performed in 17 (41%) IPX and 41 (14%) PPX patients. Although IPX patients had a longer median refractory period compared to PPX patients (340 ms vs 310 ms, P = 0.001), the incidence of APs with refractory periods ≤250 ms was similar (10% vs 12%, P = 1.0). Exercise tests were performed on 208 patients and 24 (12%) had IPX-ET. Compared with IPX patients, IPX-ET had similar median AP refractory periods (320 ms, P = 0.4) and incidence of APs with refractory periods ≤250 ms (13%, P = 1.0). CONCLUSION: Patients with IPX had longer AP refractory periods than those with PPX, but the incidence of pathways with refractory periods ≤250 ms was not significantly different. The finding of IPX on a baseline electrocardiogram does not rule out potentially high-risk pathways.