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Background: Systematic automated external defibrillator(AED) placement in schools may improve pediatric out-of-hospital cardiac arrest(OHCA) survival. To estimate their utility, we identified school-located pediatric and adult OHCAs to estimate the potential utilization of school-located AEDs. Further, we identified all OHCAs within an AED-retrievable distance of the school by walking, biking, and driving., Methods: We used prospectively collected data from the British Columbia(BC) Cardiac Arrest Registry(2013-2020), and geo-plotted all OHCAs and schools(n = 824) in BC. We identified adult and pediatric(age < 18 years) OHCAs occurring in schools, as well as nearby OHCAs for which a school-based externally-placed AED could be retrieved by a bystander prior to emergency medical system(EMS) arrival., Results: Of 16,409 OHCAs overall in the study period, 28.6 % occurred during school hours. There were 301 pediatric OHCAs. 5(1.7 %) occurred in schools, of whom 2(40 %) survived to hospital discharge. Among both children and adults, 28(0.17 %) occurred in schools(0.0042/school/year), of whom 21(75 %) received bystander resuscitation, 4(14 %) had a bystander AED applied, and 14(50 %) survived to hospital discharge. For each AED, an average of 0.29 OHCAs/year(95 % CI 0.21-0.37), 0.93 OHCAs/year(95 % CI 0.69-1.56) and 1.69 OHCAs/year(95 % CI 1.21-2.89) would be within the potential retrieval distance of a school-located AED by pedestrian, cyclist and automobile retrieval, respectively, using the median EMS response times., Conclusion: While school-located OHCAs were uncommon, outcomes were favourable. 11.1% to 60.9% of all OHCAs occur within an AED-retrievable distance to a school, depending on retrieval method. Accessible external school-located AEDs may improve OHCA outcomes of school children and in the surrounding community., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Introduction: Risk stratification tools for catecholaminergic polymorphic ventricular tachycardia (CPVT) are limited. The exercise stress test (EST) is the most important diagnostic and prognostic test. We aimed to determine whether heart rate (HR) and blood pressure (BP) response during EST were associated with the risk of arrhythmias., Materials and Methods: We studied the association between HR and BP response and ventricular arrhythmia burden on EST in 20 CPVT patients. HR reserve values <80% and ≤62% were used to define chronotropic incompetence (CI) off and on therapy, respectively. Symptoms and ventricular arrhythmia score (VAS) in all patients with respect to CI and BP during index EST off therapy and on maximal therapy were compared., Results: CI in CPVT patients off therapy was associated with a worse VAS during EST (P = .046). Patients with CI also more frequently presented with syncope and/or cardiac arrest compared to patients with a normal chronotropic response (P = .008). Once on therapy, patients with CI had similar VAS compared to patients without CI (P = .50), suggesting that treatment attenuates risk related to CI. Patients with CI also had a lower peak systolic BP (P = .041) which persisted on maximal therapy (P = .033)., Conclusion: Untreated CPVT patients with CI have more ventricular arrhythmias than those without CI. This may serve as a simple disease prognosticator that can be modified by antiarrhythmic therapy. A mechanistic link between CI and arrhythmia susceptibility remains unknown. Larger studies are needed to confirm and establish the mechanism of these findings., (© 2019 Wiley Periodicals, Inc.)

Background: There are few reports of pediatric studies of atrial fibrillation (AF). We sought to describe the clinical characteristics, management strategies, and recurrence rates and to identify predictors of AF recurrence in a contemporary pediatric population., Methods: A retrospective review was performed of patients ≤ 18 years with lone AF who were seen at 4 pediatric institutions from 1996-2011. Patients with AF in the setting of thyroid disease, ventricular pre-excitation, coexisting congenital heart disease, or a history of cardiac surgery were excluded. Demographics, clinical presentation, investigations, treatment, and follow-up were analyzed., Results: Forty-two patients were diagnosed with a first episode of lone AF, and 4 of these cases were later classified as persistent AF. Thirty-one (74%) were male patients, median age was 15.3 years, and median (interquartile range [IQR]) duration of AF episode was 12 (IQR, 7-24) hours. AF recurred in 39% (15 of 38) of patients. The Kaplan-Meier median time to estimated recurrence was 19 months. By univariate analysis, initial AF episode duration was associated with a higher risk of recurrence (hazard ratio [HR], 1.01; 95% confidence interval [CI], 1-1.02; P = 0.034). Sex, age, family history, size of the left atrium, and history of cardioversion were not associated with recurrence. Recurrence with another supraventricular tachyarrhythmia (SVT) was observed in 6 of 38 (16%) patients, and 12 patients underwent electrophysiology (EP) study, with 6 patients receiving ablation., Conclusions: Our reported rate of recurrence of 39% is important when counseling pediatric patients and their parents on the expected course and treatment goals., (Copyright © 2013 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

The diagnosis and management of prenatal tachyarrhythmias is well established; however, the postnatal course and outcomes are not. The purpose of our study was to review the natural history of patients with fetal tachycardia, determine the incidence of postnatal arrhythmias, and determine whether there are factors to predict which fetuses will develop postnatal arrhythmias. A retrospective chart review of patients with fetal tachyarrhythmias investigated at British Columbia Children's and Women's Hospitals between 1983 and 2010 was conducted. Sixty-nine mother-fetus pairs were eligible for the study. Fifty-two had fetal supraventricular tachycardia, and 17 had fetal atrial flutter. Conversion to sinus rhythm occurred prenatally in 52 % of patients. Postnatal arrhythmia occurred in two thirds of patients, with 82 % of those cases occurring within the first 48 h of life. Hydrops fetalis, female sex, and lack of conversion to sinus rhythm was predictive of postnatal arrhythmia (P = 0.01, P = 0.01, and P = 0.001, respectively). Conversion to sinus rhythm prenatally did not predict postnatal arrhythmia. Median duration of treatment was 9 months. Two postnatal deaths of unknown etiology occurred. Two thirds of all patients with prenatal tachycardia will develop postnatal arrhythmia. Prenatal factors that predict postnatal arrhythmia include hydrops, sex, and whether or not conversion to sinus rhythm occurred prenatally. The majority of patients with postnatal arrhythmia present within 48 h of life, which has clinical implications for monitoring. Postnatal outcome is generally very good with most patients being weaned off medication in 6-12 months.

Biventricular (BiV) pacing or cardiac resynchronization therapy (CRT) is an established therapy for heart failure in adults. In children, cardiac dyssynchrony occurs most commonly following repair of congenital heart disease (CHD) where multisite pacing has been shown to improve both hemodynamics and ventricular function. Determining which patient types would specifically benefit has not yet been established. A prospective, repeated measures design was undertaken to evaluate BiV pacing in a cohort of children undergoing biventricular repair for correction of their CHD. Hemodynamics, arterial blood gas, electrocardiographic (ECG), and echocardiographic data were collected. Pacing protocol was undertaken prior to the patient's extubation with 20 min of conventional right ventricular (RV) or BiV pacing, preceded and followed by 10 min of recovery time. Multivariate statistics were used to analyze the data with p values <0.05 considered significant. Twenty-five (14 female) patients underwent surgery at a median (range) age of 5.2 (0.1-37.4) months with no early mortality. The Risk-adjusted classification for Congenital Heart Surgery (RACHS) scores were 2 in 14 patients, 3 in eight patients, and 4 in three patients. None had pre-existing arrhythmias, dyssynchrony, or required pacing pre-operatively. No patient required implantation of a permanent pacemaker post-operatively. The median cardio-pulmonary bypass time was 96 (55-236) min. RV and BiV pacing did not improve cardiac index from baseline (3.23 vs. 3.42 vs. 3.39 L/min/m2; p > 0.05). The QRS duration was not changed with pacing (100 vs. 80 vs. 80 ms; p > 0.05). On echocardiography, the time-to-peak velocity difference between the septal and posterior walls (synchrony) during pacing was similar to baseline and was also not statistically significant. BiV pacing did not improve cardiac output when compared to intrinsic sinus rhythm or RV pacing in this cohort of patients. Our study has shown that BiV pacing is not indicated in children who have undergone routine BiV congenital heart surgery. Further prospective studies are needed to assess the role of multisite pacing in children with ventricular dyssynchrony such as those with single ventricles, those undergoing reoperation or those with high RACHS scores.

Background: Since 2008, all pediatric deaths in British Columbia have been reported to the coroner. The cause of death in pediatric sudden unexpected death (SUD) remains undetermined in 10% to 30% of cases. Before 2008, there was no standardized approach for referring relatives of SUD victims for follow-up medical testing to determine whether they were affected by the same condition. In the current era, genetic testing for primary electrical diseases can be used in cases of undetermined SUD when existing diagnostic methods fail., Objective: To improve the clinical care of surviving relatives of SUD victims, the current practice of assessment of SUD in British Columbia was reviewed. The study also aimed to determine the prevalence of SUD and sudden cardiac death, types of postmortem investigations performed in SUD, and the use of genetic testing for primary electrical diseases in SUD from 2005 to 2007., Methods: Cases involving individuals zero to 35 years of age, with a death due to natural disease or an undetermined cause were compiled from the British Columbia Coroners Service database. Cases were determined to be either sudden death due to a previously diagnosed condition or SUD., Results: In individuals zero to 35 years of age, the prevalence of SUD was 9.21 per 100,000 and the prevalence of sudden cardiac death was 5.26 per 100,000. There were 35 cases of SUD in which a cause of death was unidentified after autopsy (autopsy- negative SUD). Specimens were collected, and specialists were consulted in 86% of these cases in the pediatric population and 14% in the adult population. A suggestion was made to relatives to seek medical attention in 26% of the autopsy-negative SUDs, and molecular autopsy was discussed in 9% of cases but performed in none., Conclusion: Currently, SUD in British Columbia is not managed in a way that optimizes a timely diagnosis for surviving relatives. A standardized protocol for SUD is needed to ensure optimization of diagnosis, genetic testing and referral of surviving relatives.

Purpose: Hereditary long QT syndrome is named for a prolonged QT interval reflecting predisposition to ventricular arrhythmias and sudden death. A high rate in a remote, northern Canadian First Nations community was brought to attention., Methods: Two severely affected index cases and 122 relatives were ascertained using community-based participatory research principles. Genetic sequencing of five known genes responsible for long QT syndrome was carried out on the index cases, leading to the identification of a novel missense mutation. Functional properties of the identified mutation were studied in transfected mouse ltk- cells using whole cell patch clamp techniques. Corrected QT interval measurements were obtained from participants and subsequent genotyping of relatives was carried out., Results: In the two index cases, a novel missense mutation (V205M) was identified in the S3 transmembrane helix of KvLQT1, the pore forming domain of the IKs channel complex. In transfected mouse ltk-cells the V205M mutation suppressed IKs by causing a dramatic depolarizing shift in activation voltage coupled with acceleration of channel deactivation. Twenty-two mutation carriers had a significantly higher mean corrected QT interval than noncarriers (465 +/- 28 milliseconds vs. 434 +/- 26 milliseconds, P < 0.0001); however, 30% of carriers had a corrected QT interval below 440 milliseconds., Conclusion: A novel KCNQ1 mutation in this founder population likely confers increased susceptibility to arrhythmias because of decreased IKs current. Even with a common mutation within a relatively homogenous population, clinical expression remains variable, exemplifying the multifactorial nature of long QT syndrome, and supporting the difficulty of definitive diagnosis without genetic testing. A community participatory approach enabled a comprehensive evaluation of the impact.

The diagnosis of congenital long-QT syndrome (LQTS) in the relatives (nonprobands) of index patients (probands) is increasing because of screening. This report documents the clinical courses and outcomes of nonproband pediatric patients with LQTS. All patients aged <18 years with LQTS were identified at 3 pediatric centers. Demographic data, personal and family histories, electrocardiographic data, and genetic diagnoses (if available) were obtained. Probands were defined as the first patients in their families diagnosed with LQTS and nonprobands as those diagnosed by screening. Of 144 patients with LQTS, 84 (58%) were nonprobands aged 6.5+/-5.4 years with QTc intervals of 479+/-34 ms. No nonproband presented with resuscitated sudden death, atrioventricular block, or ventricular arrhythmia, but 7 (8.3%) had histories of syncope at presentation. All nonproband patients were treated. During a follow-up period of 4.7+/-3.9 years, there were no deaths in the nonproband group, but device implantation was performed in 13 (15%), 4 of whom had appropriate shocks. As expected, compared with probands, nonprobands were less symptomatic. Additionally, nonprobands were younger and had shorter QTc intervals. Although device implantation was more common in probands, there was no difference in appropriate implantable cardioverter-defibrillator shocks or mortality between the probands and their affected relatives. In conclusion, children are increasingly identified with LQTS as a result of family screening. Although phenotypic differences exist between probands and nonprobands, survival is excellent in the 2 groups with therapy. Appropriate implantable cardioverter-defibrillator discharges in the nonproband group underscore the importance of follow-up in this relatively asymptomatic population.

Objectives: We sought to assess the spectrum and outcome of young long QT syndrome (LQTS) patients, addressing treatment including device indications, risks, and benefits., Background: Long QT syndrome has a phenotype ranging from asymptomatic electrocardiogram (ECG) abnormalities to sudden death. Treatments include beta-blockers and device implantation in high-risk individuals. Despite genetic testing, accurate risk stratification remains challenging., Methods: A database search at 3 institutions identified all pediatric LQTS patients. Records were reviewed for demographics, criteria for diagnosis, treatment, follow-up, and ECG and device data., Results: We identified 128 patients ages 8.0 +/- 5.4 years with QTc of 487 +/- 39 ms and follow-up of 4.4 +/- 3.5 years. Most were diagnosed because of an abnormal ECG in a patient with a family history (53%). Genetic mutations were identified in 51 patients. Beta-blockers were used in 126 (98%) and pacemaker/implantable cardioverter-defibrillator implantation in 27 (21%) patients, usually because of symptoms despite use of beta-blockers. Pacing was common; 22% received an appropriate shock but device-related re-intervention occurred in 48%. Device patients had longer QTc intervals (p = 0.03) and more symptoms (p < 0.001). No one with an isolated KCNQ1 and all patients with an SCN5A mutation had device implantation. During the study period, there were 2 deaths., Conclusions: Long QT syndrome without symptoms is increasingly recognized as family members are screened. Evaluation of this minimally symptomatic population offers an evolving understanding of LQTS. Previous studies of highly symptomatic patients were more worrisome. In the era of genetic testing and device implantation, overall mortality is low with treatment. Device therapy, although effective, is not without complications and should be reserved for high-risk patients.

Objectives: To determine the prevalence of Kawasaki disease in older children and to evaluate its clinical presentation, time to diagnosis, and outcome in comparison with younger patients with the disease., Methodology: A retrospective analysis of all patients discharged with a diagnosis of Kawasaki disease at a pediatric tertiary care hospital over a 12-year period., Results: A total of 133 patients were included in this study; 7.5% were 9 years of age or older at the time of illness. Patients were grouped by age: infants included children age 1 to 8 years of age and children 9 years of age or older. Older children had a higher frequency of abnormal cardiovascular physical examination (50%) versus children (6%) and infants (10%). The older age group and the infants had a higher prevalence of coronary artery abnormalities and poor left ventricular function than did the 1- to 8-year-olds. Eighty percent of the older children had coronary arteries that were either dilated or aneurysmal, and 30% demonstrated left ventricular dysfunction on initial echocardiography. The number of days to diagnosis after meeting the diagnostic criteria was 5.8 +/- 2.3 for infants, 5.2 +/- 1.5 for older children, and 1.9 +/- 0.3 for children. Older children had a complicated course of Kawasaki disease compared with younger patients., Conclusion: We found a higher prevalence of older children with Kawasaki disease at our center than has previously been reported. Older patients, as well as infants, had a higher rate of coronary artery abnormalities than did the children between 1 and 8 years of age. Older age at the time of illness or a delay in treatment may be important factors in determining cardiac involvement in Kawasaki disease.