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BACKGROUND: Selection of radiofrequency ablation (RF) or cryoablation (Cryo) for atrioventricular nodal re-entrant tachycardia (AVNRT) in children remains controversial due to a lack of contemporary comparison studies in this population. OBJECTIVES: This study sought to compare outcomes of RF and Cryo for AVNRT in the pediatric population. METHODS: AVNRT ablation outcomes were retrospectively analyzed utilizing the National Cardiovascular Data Registry IMPACT (Improving Pediatric and Adult Congenital Treatment) Registry from April 2016 to March 2019. Data from subjects 1 to 21 years of age undergoing elective first-time slow pathway (SP) modification for AVNRT were included. Exclusion criteria included <1 year of age, congenital heart disease, and >1 ablation target. Cases were analyzed by ablation energy: 1) RF only; 2) Cryo only; 3) radiofrequency ablation switching to cryoablation (RFâCryo); and 4) cryoablation switching to radiofrequency ablation (CryoâRF). The primary outcome was acute ablation failure. Secondary outcomes included in-hospital adverse events. RESULTS: Among 2,448 patients (mean age 13.6 ± 3.4 years, 60% female), RF only was employed in 43% (n = 1,046), Cryo only in 49% (n = 1,201), RFâCryo in 6% (n = 135), and CryoâRF in 66 (3%). Acute ablation failure occurred in 1.3% (n = 33), with no difference by energy source (1% in RF only, 1.5% in Cryo only, 1.5% in RFâCryo, 3% in CryoâRF; P = 0.5). Atrioventricular (AV) block requiring permanent pacemaker did not occur in any group; transient AV block occurred in 0.4% of the cohort, with no difference by group. CONCLUSIONS: In this largest pediatric study of AVNRT ablation, RF and Cryo demonstrated comparable high acute success and rare documentation of AV block that did not result in temporary or permanent pacing. Longitudinal data are important for further comparison of these modalities with regard to recurrence risk and late complications.
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Youth and adult participation in sports continues to increase, and athletes may be diagnosed with potentially arrhythmogenic cardiac conditions. This international multidisciplinary document is intended to guide electrophysiologists, sports cardiologists, and associated health care team members in the diagnosis, treatment, and management of arrhythmic conditions in the athlete with the goal of facilitating return to sport and avoiding the harm caused by restriction. Expert, disease-specific risk assessment in the context of athlete symptoms and diagnoses is emphasized throughout the document. After appropriate risk assessment, management of arrhythmias geared toward return to play when possible is addressed. Other topics include shared decision-making and emergency action planning. The goal of this document is to provide evidence-based recommendations impacting all areas in the care of athletes with arrhythmic conditions. Areas in need of further study are also discussed.
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BACKGROUND: Implantable cardioverter-defibrillators last longer, and interest in reliable leads with targeted lead placement is growing. The OmniaSecure™ defibrillation lead is a novel small-diameter, catheter-delivered lead designed for targeted placement, based on the established SelectSecure SureScan MRI Model 3830 lumenless pacing lead platform. OBJECTIVE: This trial assessed safety and efficacy of the OmniaSecure defibrillation lead. METHODS: The worldwide LEADR pivotal clinical trial enrolled patients indicated for de novo implantation of a primary or secondary prevention implantable cardioverter-defibrillator/cardiac resynchronization therapy defibrillator, all of whom received the study lead. The primary efficacy end point was successful defibrillation at implantation per protocol. The primary safety end point was freedom from study lead-related major complications at 6 months. The primary efficacy and safety objectives were met if the lower bound of the 2-sided 95% credible interval was >88% and >90%, respectively. RESULTS: In total, 643 patients successfully received the study lead, and 505 patients have completed 12-month follow-up. The lead was placed in the desired right ventricular location in 99.5% of patients. Defibrillation testing at implantation was completed in 119 patients, with success in 97.5%. The Kaplan-Meier estimated freedom from study lead-related major complications was 97.1% at 6 and 12 months. The trial exceeded the primary efficacy and safety objective thresholds. There were zero study lead fractures and electrical performance was stable throughout the mean follow-up of 12.7 ± 4.8 months (mean ± SD). CONCLUSION: The OmniaSecure lead exceeded prespecified primary end point performance goals for safety and efficacy, demonstrating high defibrillation success and a low occurrence of lead-related major complications with zero lead fractures.
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BACKGROUND: The Apple Watch™ (AW) offers heart rate (HR) tracking by photoplethysmography (PPG) and single-lead electrocardiographic (ECG) recordings. The accuracy of AW-HR and diagnostic performance of AW-ECGs among children during both sinus rhythm and arrhythmias have not been explored. OBJECTIVE: The purposes of this study were to assess the accuracy of AW-HR measurements compared to gold standard modalities in children during sinus rhythm and arrhythmias and to identify non-sinus rhythms using AW-ECGs. METHODS: Subjects ≤18 years wore an AW during (1) telemetry admission, (2) electrophysiological study (EPS), or (3) exercise stress test (EST). AW-HRs were compared to gold standard modality values. Recorded AW-ECGs were reviewed by 3 blinded pediatric electrophysiologists. RESULTS: Eighty subjects (median age 13 years; interquartile range 1.0-16.0 years; 50% female) wore AW (telemetry 41% [n = 33]; EPS 34% [n = 27]; EST 25% [n = 20]). A total of 1090 AW-HR measurements were compared to time-synchronized gold standard modality HR values. Intraclass correlation coefficient (ICC) was high 0.99 (0.98-0.99) for AW-HR during sinus rhythm compared to gold standard modalities. ICC was poor comparing AW-HR to gold standard modality HR in tachyarrhythmias (ICC 0.24-0.27) due to systematic undercounting of AW-HR values. A total of 126 AW-ECGs were reviewed. Identification of non-sinus rhythm by AW-ECG showed sensitivity of 89%-96% and specificity of 78%-87%. CONCLUSIONS: We found high levels of agreement for AW-HR values with gold standard modalities during sinus rhythm and poor agreement during tachyarrhythmias, likely due to hemodynamic effects of tachyarrhythmias on PPG-based measurements. AW-ECGs had good sensitivity and moderate specificity in identification of non-sinus rhythm in children.
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Arritmia Sinusal , Electrocardiografía , Frecuencia Cardíaca , Fotopletismografía , Dispositivos Electrónicos Vestibles , Humanos , Masculino , Femenino , Lactante , Preescolar , Niño , Adolescente , Fotopletismografía/instrumentación , Fotopletismografía/métodos , Electrocardiografía/instrumentación , Electrocardiografía/métodos , Dispositivos Electrónicos Vestibles/normas , Arritmia Sinusal/diagnóstico , Exactitud de los DatosRESUMEN
Transcatheter leadless pacemakers have benefits in congenital heart disease because they eliminate the risks of lead malfunction, venous occlusions, and pocket complications. This newest pacemaker's utility in this population has been limited by the large sheath and delivery system, need for atrioventricular synchronous pacing, lack of explantation options, and possible lack of adequate access to the subpulmonary ventricle. With careful planning, leadless pacing can be successfully performed in these patients. Consideration of nonfemoral access, alternative implant sites to avoid myocardial scar or prosthetic material, anticoagulation for patients with persistent intracardiac shunts or systemic ventricular implantation, and operator experience are critical.
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Cardiopatías Congénitas , Marcapaso Artificial , Humanos , Estimulación Cardíaca Artificial , Ventrículos Cardíacos , Cardiopatías Congénitas/terapia , MiocardioRESUMEN
BACKGROUND: Published guidelines provide recommendations for risk stratification in pediatric Wolff-Parkinson-White (WPW). There are no data on provider concordance with these guidelines. We hypothesized that significant practice variation exists between pediatric cardiologists (PC) and electrophysiologists (EP). METHOD: The records of all patients, age 8 to 21 years, with a new ECG diagnosis of WPW between 1/1/2013 and 12/31/2018, from a single center, were retrospectively reviewed. Subjects were categorized on the basis of symptoms and resting ECG findings as one of the following: asymptomatic intermittent WPW, asymptomatic persistent WPW, or symptomatic WPW. The performance and results of diagnostic testing, including Holter monitor, event monitor, exercise stress test (EST), and electrophysiology study (EPS), were recorded. The primary outcome was concordance with published guidelines. A secondary outcome was documentation of a discussion of sudden cardiac death (SCD) risk. RESULTS: 615 patient encounters were analyzed in 231 patients with newly diagnosed WPW pattern on ECG (56% male; mean age at diagnosis 13.9 ± 2.5 years). EP were observed to have a significantly higher rate of guideline concordance than PC (95% vs. 71%, p < 0.001). There was significant practice variation between PC and EP in the documentation of a discussion of SCD risk: 96% in EP vs. 39% in PC (p < 0.001). CONCLUSION: Significant practice variation exists in the non-invasive and invasive risk stratification of pediatric WPW, with lower concordance to published guidelines amongst PC, when compared to EP. This report highlights the need to promote awareness of current WPW guidelines in the pediatric cardiology community at large.
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BACKGROUND: Guidelines addressing magnetic resonance imaging (MRI) in patients with cardiac implantable electronic devices (CIEDs) provide algorithms for imaging pediatric and congenital heart disease (CHD) patients. Guideline acceptance varies by institution. Guidelines also do not support routine MRI scans in patients with epicardial or abandoned leads, common in pediatric and CHD patients. OBJECTIVE: The purpose of this study was to determine the incidence of MRI-related complications in pediatric and CHD patients with CIEDs, including epicardial and/or abandoned leads. METHODS: A multicenter retrospective review included patients with CIEDs who underwent any MRI between 2007 and 2022 at congenital cardiac centers. The primary outcome was any patient adverse event or clinically significant CIED change after MRI, defined as pacing lead capture threshold increase >0.5 V with output change, P- or R- wave amplitude decrease >50% with sensitivity change, or impedance change >50%. RESULTS: Across 14 institutions, 314 patients (median age 18.8 [1.3; 31.4] years) underwent 389 MRIs. There were 288 pacemakers (74%) and 87 implantable cardioverter-defibrillators (22%); 52% contained epicardial leads, and 14 (4%) were abandoned leads only. Symptoms or CIED changes occurred in 4.9% of MRI scans (6.1% of patients). On 9 occasions (2%), warmth or pain occurred. Pacing capture threshold or lead impedance changes occurred in 1.4% and 2.0% of CIEDs post-MRI and at follow-up. CONCLUSION: Our data provide evidence that MRIs can be performed in pediatric and CHD patients with CIEDs, including non-MRI-conditional CIEDs and epicardial and/or abandoned leads, with rare minor symptoms or CIED changes but no other complications.
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Desfibriladores Implantables , Cardiopatías Congénitas , Marcapaso Artificial , Adolescente , Niño , Humanos , Cardiopatías Congénitas/diagnóstico , Cardiopatías Congénitas/terapia , Imagen por Resonancia Magnética/métodos , Estudios Retrospectivos , Lactante , Preescolar , Adulto Joven , AdultoAsunto(s)
Bloqueo Atrioventricular , Marcapaso Artificial , Humanos , Niño , Bloqueo Atrioventricular/terapiaRESUMEN
BACKGROUND: Transcatheter Leadless Pacemakers (TLP) are a safe and effective option for adults with pacing indications. These devices may be an alternative in pediatric patients and patients with congenital heart disease for whom repeated sternotomies, thoracotomies, or transvenous systems are unfavorable. However, exemption of children from clinical trials has created uncertainty over the indications, efficacy, and safety of TLP in the pediatric population. The objectives of this study are to evaluate clinical indications, procedural characteristics, electrical performance, and outcomes of TLP implantation in children. METHODS: Retrospective data were collected from patients enrolled in the Pediatric and Congenital Electrophysiology Society TLP registry involving 15 centers. Patients ≤21 years of age who underwent Micra (Medtronic Inc, Minneapolis, MN) TLP implantation and had follow-up of ≥1 week were included in the study. RESULTS: The device was successfully implanted in 62 of 63 registry patients (98%) at a mean age of 15±4.1 years and included 20 (32%) patients with congenital heart disease. The mean body weight at TLP implantation was 55±19 kg and included 8 patients ≤8 years of age and ≤30 kg in weight. TLP was implanted by femoral (n=55, 87%) and internal jugular (n=8, 12.6%) venous approaches. During a mean follow-up period of 9.5±5.3 months, there were 10 (16%) complications including one cardiac perforation/pericardial effusion, one nonocclusive femoral venous thrombus, and one retrieval and replacement of TLP due to high thresholds. There were no deaths, TLP infections, or device embolizations. Electrical parameters, including capture thresholds, R wave sensing, and pacing impedances, remained stable. CONCLUSIONS: Initial results from the Pediatric and Congenital Electrophysiology Society TLP registry demonstrated a high level of successful Micra device implants via femoral and internal venous jugular approaches with stable electrical parameters and infrequent major complications. Long-term prospective data are needed to confirm the reproducibility of these initial findings.
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Cardiopatías Congénitas , Marcapaso Artificial , Adulto , Humanos , Niño , Adolescente , Adulto Joven , Recién Nacido , Estudios Prospectivos , Estudios Retrospectivos , Reproducibilidad de los Resultados , Resultado del Tratamiento , Diseño de Equipo , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/terapia , Cardiopatías Congénitas/diagnóstico , Cardiopatías Congénitas/terapiaRESUMEN
BACKGROUND: Guidelines for electrophysiology study (EPS) and catheter ablation in Wolff-Parkinson-White (WPW) are age based, but size may be a more relevant factor in determination of outcomes. OBJECTIVES: The goal of this study was to evaluate the association of patient weight with outcomes of catheter ablation for pediatric WPW. METHODS: A multicenter retrospective cohort study was performed on children aged 1 to 21 years with WPW and first-time EPS from April 2016 to December 2019 recorded in the IMPACT (Improving Pediatric and Adult Congenital Treatment) registry, excluding those with congenital heart disease, cardiomyopathy, and >1 ablation target. A weight threshold of 30 kg was selected, representing 1 SD below the cohort mean. The primary outcome was major adverse events (MAEs); additional outcomes included deferred ablation, use of cryoablation, and ablation success. RESULTS: A total of 4,456 subjects from 84 centers were evaluated, with 14% weighing <30 kg. Subjects weighing <30 kg were more likely to have preprocedural supraventricular tachycardia (45% vs 29%; P < 0.001) and less likely to have right septal accessory pathways (25% vs 33%; P < 0.001). MAEs were rare, although with higher incidence in the <30 kg cohort (0.3% vs 0.05%; P = 0.04). No difference was seen in likelihood of deferred ablation (9% vs 12%; P = 0.07) or use of cryoablation (11% vs 11%; P = 0.70). Success was higher in the <30 kg cohort: 95% vs 92% (P = 0.009). This effect persisted after adjusting for covariates (odds ratio: 1.6; 95% CI: 1.01-2.70; P = 0.046). CONCLUSIONS: Weight <30 kg was associated with a small but elevated risk of MAEs. Rates of deferred ablation and cryoablation were similar. Adjusting for factors (including accessory pathway type and location), weight <30 kg remained an independent predictor of acute success.
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Fascículo Atrioventricular Accesorio , Taquicardia Supraventricular , Síndrome de Wolff-Parkinson-White , Adulto , Humanos , Niño , Síndrome de Wolff-Parkinson-White/epidemiología , Síndrome de Wolff-Parkinson-White/cirugía , Estudios Retrospectivos , Fascículo Atrioventricular Accesorio/cirugía , Sistema de RegistrosRESUMEN
Background There are few US Food and Drug Administration (FDA)-approved devices specifically aimed at the pediatric patient with arrhythmia. This has led to a high off-label utilization of devices in this vulnerable population. The Pediatric and Congenital Electrophysiology Society (PACES), the international organization representing pediatric and congenital heart disease arrhythmia specialists, developed a task force to comprehensively address device development issues relevant to pediatric patients with congenital arrhythmia. Methods and Results As a first step, the taskforce developed a 26-question survey for the pediatric arrhythmia community to assess providers' understanding of the FDA approval process, specifically in regard to pediatric labeling. There were 92/211 respondents (44%) with a >90% completion rate. The vast majority of respondents believed there was a paucity of devices available for children (96%). More than 60% of respondents stated that they did not understand the FDA regulatory process and were not aware of whether the devices they used were labeled for pediatric use. Conclusions Pediatric electrophysiologists are keenly aware of the deficit of available pediatric devices for their patients. The majority do not understand the FDA approval process and could benefit from additional educational resources regarding this. A collaborative forum including PACES, FDA, patients and their families, and Industry would be an important next step in clarifying opportunities and priorities to serve this vulnerable population.
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Arritmias Cardíacas , Cardiopatías Congénitas , Humanos , Niño , Estados Unidos , United States Food and Drug Administration , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/terapia , Cardiopatías Congénitas/diagnóstico , Cardiopatías Congénitas/terapia , Encuestas y Cuestionarios , ElectrofisiologíaRESUMEN
Background The objective of this international multicenter study was to investigate both early and late outcomes of cardiac resynchronization therapy (CRT) in patients with a systemic right ventricle (SRV) and to identify predictors for congestive heart failure readmissions and mortality. Methods and Results This retrospective international multicenter study included 13 centers. The study population comprised 80 adult patients with SRV (48.9% women) with a mean age of 45±14 (range, 18-77) years at initiation of CRT. Median follow-up time was 4.1 (25th-75th percentile, 1.3-8.3) years. Underlying congenital heart disease consisted of congenitally corrected transposition of the great arteries and dextro-transposition of the great arteries in 63 (78.8%) and 17 (21.3%) patients, respectively. CRT resulted in significant improvement in functional class (before CRT: III, 25th-75th percentile, II-III; after CRT: II, 25th-75th percentile, II-III; P=0.005) and QRS duration (before CRT: 176±27; after CRT: 150±24 milliseconds; P=0.003) in patients with pre-CRT ventricular pacing who underwent an upgrade to a CRT device (n=49). These improvements persisted during long-term follow-up with a marginal but significant increase in SRV function (before CRT; 30%, 25th-75th percentile, 25-35; after CRT: 31%, 25th-75th percentile, 21-38; P=0.049). In contrast, no beneficial change in the above-mentioned variables was observed in patients who underwent de novo CRT (n=31). A quarter of all patients were readmitted for heart failure during follow-up, and mortality at latest follow-up was 21.3%. Conclusions This international experience with CRT in patients with an SRV demonstrated that CRT in selected patients with SRV dysfunction and pacing-induced dyssynchrony yielded consistent improvement in QRS duration and New York Heart Association functional status, with a marginal increase in SRV function.
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Terapia de Resincronización Cardíaca , Insuficiencia Cardíaca , Transposición de los Grandes Vasos , Humanos , Adulto , Femenino , Persona de Mediana Edad , Masculino , Terapia de Resincronización Cardíaca/efectos adversos , Terapia de Resincronización Cardíaca/métodos , Ventrículos Cardíacos , Estudios Retrospectivos , Resultado del Tratamiento , Insuficiencia Cardíaca/diagnóstico , Insuficiencia Cardíaca/terapiaRESUMEN
Children, adolescents, and young adults with conditions such as cardiomyopathies and channelopathies are at higher risk of sudden cardiac death caused by lethal arrhythmias, especially ventricular fibrillation. Timely defibrillation saves lives. Patients thought to be at significantly high risk of sudden death typically undergo placement of an implantable cardioverter-defibrillator. Patients thought to be at lower risk are typically followed medically but do not undergo implantable cardioverter-defibrillator placement. However, low risk does not equal no risk. Compared with the general population, many of these patients are at significantly higher risk for lethal arrhythmias. We make the case that such individuals and families will benefit from having an at-home automatic external defibrillator. Used in conjunction with conventional measures such as training on cardiopulmonary resuscitation, an at-home automatic external defibrillator could lead to significantly shortened time to defibrillation with better overall and neurological survival. We recommend that the cost of such home automatic external defibrillators should be covered by medical insurance.
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Reanimación Cardiopulmonar , Desfibriladores , Adolescente , Arritmias Cardíacas/complicaciones , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/terapia , Niño , Muerte Súbita Cardíaca/etiología , Muerte Súbita Cardíaca/prevención & control , Desfibriladores/efectos adversos , Humanos , Fibrilación Ventricular/complicaciones , Fibrilación Ventricular/terapia , Adulto JovenRESUMEN
Background Insertable cardiac monitors (ICMs) are effective in the detection of paroxysmal arrhythmias. In 2014, the first miniaturized ICM was introduced with a less invasive implant technique. The impact of this technology on ICM use in pediatric patients has not been evaluated. We hypothesized an increase in annual pediatric ICM implants starting in 2014 attributable to device miniaturization. Methods and Results A retrospective observational study was conducted using administrative claims from MarketScan Medicaid and commercial insurance claims databases. Use of ICM between January 2013 and December 2018 was measured (normalized to the total enrolled population ≤18 years) and compared with balancing measures (Holter ambulatory monitors, cardiac event monitors, encounters with syncope diagnosis, implantation of implantable cardioverter-defibrillator/pacemaker). Secondary analyses included evaluations of subsequent interventions and complications. The study cohort included 33 532 185 individual subjects, of which 769 (0.002%) underwent ICM implantation. Subjects who underwent ICM implantation were 52% male sex, with a median age of 16 years (interquartile range, 10-17 years). A history of syncope was present in 71%, palpitations in 43%, and congenital heart disease in 28%. Following release of the miniaturized ICM, use of ICMs increased from 5 procedures per million enrollees in 2013 to 11 per million between 2015 and 2018 (P<0.001), while balancing measures remained static. Of 394 subjects with ≥1 year of follow-up after implantation, interventions included catheter ablation in 24 (6%), pacemaker implantation in 15 (4%), and implantable cardioverter-defibrillator implantation in 7 (2%). Conclusions Introduction of the miniaturized ICM was followed by a rapid increase in pediatric use. The effects on outcomes and value deserve further attention.
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Desfibriladores Implantables , Electrocardiografía Ambulatoria , Adolescente , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/epidemiología , Arritmias Cardíacas/terapia , Niño , Electrocardiografía Ambulatoria/métodos , Femenino , Humanos , Masculino , Medicaid , Miniaturización/métodos , SíncopeRESUMEN
Sudden cardiac death (SCD) accounts for up to 25% of deaths in patients with congenital heart disease (CHD). To date, research has largely been driven by observational studies and real-world experience. Drawbacks include varying definitions, incomplete taxonomy that considers SCD as a unitary diagnosis as opposed to a terminal event with diverse causes, inconsistent outcome ascertainment, and limited data granularity. Notwithstanding these constraints, identified higher-risk substrates include tetralogy of Fallot, transposition of the great arteries, cyanotic heart disease, Ebstein anomaly, and Fontan circulation. Without autopsies, it is often impossible to distinguish SCD from non-cardiac sudden deaths. Asystole and pulseless electrical activity account for a high proportion of SCDs, particularly in patients with heart failure. High-quality cardiopulmonary resuscitation is essential to improve outcomes. Pulmonary hypertension and CHD complexity are associated with lower likelihood of successful resuscitation. Risk stratification for primary prevention implantable cardioverter-defibrillators (ICDs) should consider the probability of SCD due to a shockable rhythm, competing causes of mortality, complications of ICD therapy, and associated costs. Risk scores to better estimate probabilities of SCD and CHD-specific guidelines and consensus-based recommendations have been proposed. The subcutaneous ICD has emerged as an attractive alternative to transvenous systems in those with vascular access limitations, prior device infections, intra-cardiac shunts, or a Fontan circulation. Further improving SCD-related outcomes will require a multidimensional approach to research that addresses disease processes and triggers, taxonomy to better reflect underlying pathophysiology, high-risk features, early warning signs, access to high-quality cardiopulmonary resuscitation and specialized care, and preventive therapies tailored to underlying mechanisms.
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Desfibriladores Implantables , Procedimiento de Fontan , Paro Cardíaco , Cardiopatías Congénitas , Transposición de los Grandes Vasos , Muerte Súbita Cardíaca/epidemiología , Muerte Súbita Cardíaca/etiología , Muerte Súbita Cardíaca/prevención & control , Desfibriladores Implantables/efectos adversos , Procedimiento de Fontan/efectos adversos , Cardiopatías Congénitas/terapia , Humanos , Factores de RiesgoRESUMEN
BACKGROUND: Previous estimates of life-threatening event (LTE) risk in Wolff-Parkinson-White (WPW) syndrome are limited by selection bias inherent to tertiary care referral-based cohorts. OBJECTIVE: This analysis sought to measure LTE incidence in children with WPW syndrome in a large contemporary representative population. METHODS: A retrospective cohort study was conducted using claims data from the IBM MarketScan Research Databases, evaluating subjects with WPW syndrome (age 1-18 years) from any encounter between January 1, 2013, and December 31, 2018. Subjects with congenital heart disease and cardiomyopathy 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 controls without WPW syndrome (3:1 ratio). RESULTS: The prevalence of WPW syndrome was 0.03% (8733/26,684,581) over a median follow-up of 1.6 years (interquartile range 0.7-2.9 years). Excluding congenital heart disease/cardiomyopathy, 6946 subjects were analyzed. An LTE occurred in 49 subjects (0.7%), including VF in 20 (0.3%). The incidence of VF was 0.8 events per 1000 person-years, and the incidence of LTE was 1.9 events per 1000 person-years. There were no occurrences of VF in controls; the rate of LTE was 70 times higher in subjects with WPW syndrome (0.7%; 95% confidence interval 0.5%-0.9%) than in controls (0.01%; 95% confidence interval 0%-0.02%). CONCLUSION: The use of a large claims data set allowed for an evaluation of VF and LTE risk in an unselected pediatric population with WPW syndrome. The observed range of 0.8-1.9 events per 1000 person-years is consistent with prior reports from selected populations. A comparison of event rates to matched controls confirms and quantifies the significant elevation in VF and LTE risk in pediatric WPW syndrome.