<p><strong>BACKGROUND: </strong>Previous estimates of life-threatening event (LTE) risk in Wolff-Parkinson-White (WPW) are limited by selection bias inherent to tertiary referral-based cohorts.</p>

<p><strong>OBJECTIVE: </strong>This analysis sought to measure LTE incidence in children with WPW in a large contemporary representative population.</p>

<p><strong>METHODS: </strong>A retrospective cohort study was conducted using claims data from the IBM MarketScan® Research Databases, evaluating WPW patients (age 1-18 years) from any encounter between 1/1/2013 and 12/31/2018. Subjects with congenital heart disease (CHD) and cardiomyopathy (CM) were excluded. The primary outcome was diagnosis of ventricular fibrillation (VF); a composite outcome, LTE, was defined as occurrence of VF and/or cardiac arrest. VF and LTE rates were compared to matched representative non-WPW controls (3:1 ratio).</p>

<p><strong>RESULTS: </strong>Prevalence of WPW was 0.03% (8,733/26,684,581) over median follow-up of 1.6 years (IQR 0.7-2.9). Excluding CHD/CM, 6,946 subjects were analyzed. LTE occurred in 49 subjects, including VF in 20. Incidence of VF was 0.8 events per 1000 person-years, and incidence of LTE was 1.9 events per 1000 person-years. There were no occurrences of VF in controls; rate of LTE was 70 times greater in WPW (0.7%, 95% CI: 0.5-0.9%) than in controls (0.01%, 95% CI: 0-0.02%).</p>

<p><strong>CONCLUSION: </strong>Use of a large claims dataset allowed for evaluation of VF and LTE risk in an unselected pediatric WPW population. The observed range of 0.8-1.9 events per 1000 person-years is consistent with prior reports from selected populations. Comparison of event rates to matched controls confirms and quantifies the significant elevation in VF and LTE risk in pediatric WPW.</p>

<p>- Anesthesia strategies for pediatric ablation procedures include general anesthesia (GA) and monitored anesthesia care (MAC). The effects of anesthesia strategy on arrhythmia inducibility and procedural outcomes have not been investigated. - A multicenter retrospective study was performed, utilizing data from the NCDR IMPACT Registry. Data from subjects 1-21 years undergoing elective first-time electrophysiology study (EPS) for evaluation of documented SVT, EAT, or PVC/VT from 4/1/16-12/31/19 were included, excluding cases with WPW, congenital heart disease, and/or cardiomyopathy. The primary outcome was a negative EPS, defined as failure to induce the clinical tachyarrhythmia. Secondary outcomes included ablation success and adverse events (AE). - 6621 subjects from 78 centers were evaluated: 49% male; mean age 13.3±3.8 years. GA was utilized in 5913 (89%), with MAC in 708 (11%). A negative EPS occurred in 9% of cases overall, with no difference by anesthesia strategy (9% GA vs. 10% MAC, p=0.2). In SVT and EAT, there was no significant difference in likelihood of a negative EPS by anesthesia strategy. In PVC/VT, there was a higher rate of negative EPS under GA (28% GA vs. 16% MAC, p=0.02), translating to a higher rate of non-ablation (34% GA vs. 14% MAC, p&lt;0.001). In multivariable models, GA was associated with negative EPS in PVC/VT (OR 2.2, 95% CI 1.1-4.4, p=0.03), but not in SVT or EAT. Acute ablation success was not different between strategies (94% GA vs. 94% MAC, p=0.2). Major AE were rare, with no differences between GA and MAC. - In this first report on pediatric ablation data in IMPACT, there were no differences between GA and MAC in SVT or EAT inducibility, acute ablation success, or major AE. GA was associated with higher rates of non-inducibility and non-ablation in PVC/VT cases. A MAC strategy should be considered for PVC/VT ablation in the pediatric population.</p>