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Aim: The Combining Mechanisms for Better Outcomes randomized controlled trial assessed the effectiveness of various spinal cord stimulation (SCS) modalities for chronic pain. Specifically, combination therapy (simultaneous use of customized sub-perception field and paresthesia-based SCS) versus monotherapy (paresthesia-based SCS) was evaluated. Methods: Participants were prospectively enrolled (key inclusion criterion: chronic pain for ≥6 months). Primary end point was the proportion with ≥50% pain reduction without increased opioids at the 3 month follow-up. Patients were followed for 2 years. Results: The primary end point was met (n = 89; p Clinical Trial Registration: NCT03689920 ( ClinicalTrials.gov ), Combining Mechanisms for Better Outcomes (COMBO)

Aim: The availability of long-term (>2 years) safety outcomes of spinal cord stimulation (SCS) remains limited. We evaluated safety in a global SCS registry for chronic pain. Methods: Participants were prospectively enrolled globally at 79 implanting centers and followed out to 3 years after device implantation. Results: Of 1881 participants enrolled, 1289 received a permanent SCS implant (1776 completed trial). The annualized rate of device explant was 3.5% (all causes), and 1.1% due to inadequate pain relief. Total incidence of device explantation >3 years was 7.6% (n = 98). Of these, 32 subjects (2.5%) indicated inadequate pain relief as cause for removal. Implant site infection (11 events) was the most common device-related serious adverse event ( Clinical Trial Registration: NCT01719055 ( ClinicalTrials.gov )

Background Major congenital heart disease (CHD) is associated with impaired neurodevelopment (ND), partly from prenatal insults. In this study we explore associations between 2nd and 3rd trimester umbilical (UA) and middle cerebral artery (MCA) pulsatility index (PI = systolic-diastolic velocities/mean velocity) in fetuses with major CHD and 2-year ND and growth outcomes. Methods Eligible patients included those with a prenatal diagnosis of CHD from 2007–2017 without a genetic syndrome who underwent previously defined cardiac surgeries and 2-year biometric and ND assessments in our program. UA and MCA-PI Z-scores at fetal echocardiography were examined for relationships with 2-year Bayley Scales of Infant and Toddler Development and biometric Z-scores. Results Data from 147 children was analyzed. Second and 3rd trimester fetal echocardiograms were performed at 22.4 ± 3.7 and 34.7 ± 2.9 weeks (mean ± SD), respectively. Multivariable regression analysis showed an inverse relationship between 3rd trimester UA-PI for all CHD and cognitive − 1.98(-3.37,-0.59), motor − 2.57(-4.15,-0.99), and language − 1.67(-3.3,-0.03) (effect size and 95th confidence interval) ND domains (p

Background Children with congenital heart disease (CHD) are at risk of adverse long-term neurodevelopmental outcomes, believed to be, in part, secondary to prenatal insults. Placental pathology and altered fetal middle cerebral arterial (MCA) flow suggestive of brain sparing have been documented in fetal CHD. In the present study we investigated the relationship between MCA and umbilical arterial (UA) flow patterns in fetal transposition of the great arteries (d-TGA) and hypoplastic left heart syndrome (HLHS) and growth and 2-year neurodevelopmental outcomes. Methods We included children with d-TGA and HLHS who had third-trimester fetal echocardiograms between 2004 and 2014, at which time umbilical artery (UA) and MCA pulsatility indices (PIs) were measured, and who underwent 2-year growth and neurodevelopmental assessments. Results We identified 24 children with d-TGA and 36 with HLHS. Mean age at fetal echocardiography was 33.8 ± 3.5 weeks. At 2-year follow-up, head circumference z score (standard deviation [SD]) was –0.09 (1.07) and 0.17 (1.7) for the d-TGA and HLHS groups, respectively. Bayley III mean (SD) cognitive, language, and motor scores were 97.7 (10.8), 94.7 (13.4), and 98.6 (8.6) for the d-TGA group and 90.3 (13.9), 87.2 (17.5), and 85.3 (16.2) for the HLHS group. On multivariate linear regression analysis, UA-PI was associated (effect sizes [95% CI]) with length (–1.45 [–2.7, –0.17], P = 0.027), weight (–1.46 [–2.6 to –0.30], P = 0.015) and cognitive scores (–14.86 [–29.95 to 0.23], P = 0.05) at 2 years of age. MCA PI showed no statistically significant correlation. Conclusions In fetal d-TGA and HLHS, a higher UA-PI in the third trimester, suggestive of placental insufficiency—but not MCA-PI—is associated with worse 2-year growth and neurodevelopment.

We sought to evaluate the prevalence and factors associated with "optimal" neurodevelopmental outcomes in 4- to 6-year-old children with Fontan circulation.Patients followed through the Western Canadian Complex Pediatric Therapies Follow-Up Program, and born between September 1996 and December 2015, were included. Optimal neurodevelopmental outcome was defined as full-scale intelligence quotient; visual-motor integration; adaptive behaviour assessment system-general adaptive composite scores of ≥ 80 each; and the absence of chronic motor disability, permanent hearing loss, visual impairment, and seizure disorder. Multivariable regression models and decision algorithms evaluated variables associated with optimal outcomes.The Fontan procedure was completed on 225 children, with neurodevelopmental outcome data available for 205 (mean [standard deviation]) age at Fontan 3.4 (0.9) years, 37% female). Optimal neurodevelopmental outcome was identified in 55% (112 of 205). Factors independently associated with optimal neurodevelopmental outcome were female sex (odds ratio [OR], 2.1; 95% confidence interval [CI] 1.1-4.1), years of maternal schooling (OR, 1.2 [1.1-1.4]), age at Fontan (years) (OR, 0.97 [0.94-1.0]), need for concomitant atrioventricular valve (AVV) intervention (OR, 0.4 [0.2-1.0]), and time (hours) for lactate to be ≤ 2 mmol/L (OR, 0.9 [0.8-1.0]). Of those with Fontan completion3.25 years, without concomitant AVV intervention and lactate normalization within 8 hours post-Fontan, 87% (27 of 31) had optimal neurodevelopmental outcomes.Optimal neurodevelopmental outcome was present in more than one-half of 4- to 6-year-old children with Fontan circulation in this cohort study, with important associated factors identified, including potentially modifiable factors such as younger age at Fontan surgery and lack of concomitant AVV intervention.

Background: The Hearts in Rhythm Organization (HiRO) is a team of Canadian inherited heart rhythm and cardiomyopathy experts, genetic counsellors, nurses, researchers, patients, and families dedicated to the detection of inherited arrhythmias and cardiomyopathies, provision of best therapies, and protection from the tragedy of sudden cardiac arrest. Methods: Recently, existing disease-specific registries were merged into the expanded National HiRO Registry, creating a single common data set for patients and families with inherited conditions that put them at risk for sudden death in Canada. Eligible patients are invited to participate in the registry and optional biobank from 20 specialized cardiogenetics clinics across Canada. Results: Currently, there are 4700 participants enrolled in the National HiRO Registry, with an average of 593 participants enrolled annually over the past 5 years. The capacity to enable knowledge translation of research findings is built into HiRO’s organizational infrastructure, with 3 additional working groups (HiRO Clinical Care Committee, HiRO Active Communities Committee, and HiRO Annual Symposium Committee), supporting the organization’s current goals and priorities as set alongside patient partners. Conclusion: The National HiRO Registry aims to be an integrated research platform to which researchers can pose novel research questions leading to a better understanding, detection, and clinical care of those living with inherited heart rhythm and cardiomyopathy conditions and ultimately to prevent sudden cardiac death. Résumé: Contexte: La Hearts in Rhythm Organization (HiRO) est une équipe d’experts canadiens en matière de rythmes cardiaques et de cardiomyopathies héréditaires, de conseillers en génétique, d’infirmières, de chercheurs, de patients et de familles qui se consacrent à la détection des arythmies et des cardiomyopathies héréditaires, à la mise en place des meilleures thérapies et à la protection contre la tragédie que représente une mort subite d’origine cardiaque. Méthodes: Récemment, les registres existants relatifs à des maladies spécifiques ont été fusionnés en un registre national élargi de l’HiRO, créant ainsi un ensemble de données commun unique à destination des patients et leurs familles, atteints de maladies héréditaires, qui sont à risque de mort subite au Canada. Les patients admissibles sont invités à s’associer au registre et à la biobanque facultative regroupant 20 cliniques spécialisées en cardiogénétique au Canada. Résultats: Actuellement, 4 700 participants sont inscrits au registre national de l’HiRO, avec une moyenne de 593 participants inscrits chaque année au cours des cinq dernières années. La capacité à favoriser l’application des connaissances issues de la recherche fait partie de la structure organisationnelle de l’HiRO, avec trois groupes de travail supplémentaires (comité des soins cliniques de l’HiRO, comité des communautés cctives de l’HiRO et comité du symposium annuel de l’HiRO), soutenant les objectifs et les priorités actuels de l’organisation tels qu’ils ont été fixés en partenariat avec les patients. Conclusion: Le registre national de l’HiRO vise à devenir une plateforme de recherche intégrée au sein de laquelle les chercheurs peuvent exposer des questions de recherche inédites permettant de mieux comprendre, détecter et soigner les personnes atteintes de troubles du rythme cardiaque et de cardiomyopathie héréditaires et, à terme, de prévenir la mort subite d’origine cardiaque.

Background:We evaluated a cohort of 35 children diagnosed with long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, hypertrophic cardiomyopathy, or arrhythmogenic right ventricular cardiomyopathy with regard to physical and psychosocial well-being.Material and Methods:Patients wore an accelerometer to record their time involved in moderate- to vigorous-intensity physical activity and completed the Pediatric Quality of Life Inventory and the Pediatric Cardiac Quality of Life Inventory. Parents were also asked to describe if their child had changed their physical activity because of their diagnosis and how difficult and upsetting it was for the child to adapt to the physical activity recommendations.Results:Patients were involved in less moderate- to vigorous-intensity physical activity per day (35 min/day versus 55 min/day) and had lower Pediatric Quality of Life Inventory total health scores (79 versus 84) compared to normative data. Overall, 51% of the cohort modified their physical activity in some way because of their diagnosis and changing physical activity was associated with lower Pediatric Quality of Life Inventory and Pediatric Cardiac Quality of Life Inventory scores.Conclusion:Our cohort was involved in less moderate- to vigorous-intensity physical activity and had lower Pediatric Quality of Life Inventory total health scores compared to normative paediatric data. Modifying one’s physical activity was associated with worse health-related quality of life scores, highlighting a vulnerable sub-group of children. These findings are useful for families and healthcare professionals caring for children who are adjusting to a new cardiac diagnosis of an inherited arrhythmia or cardiomyopathy.

Background: Symptomatic children with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for recurrent arrhythmic events. β-Blockers decrease this risk, but studies comparing individual β-blockers in sizeable cohorts are lacking. We aimed to assess the association between risk for arrhythmic events and type of β-blocker in a large cohort of symptomatic children with CPVT. Methods: From 2 international registries of patients with CPVT, RYR2 variant–carrying symptomatic children (defined as syncope or sudden cardiac arrest before β-blocker initiation and age at start of β-blocker therapy Results: We included 329 patients (median age at diagnosis, 12 [interquartile range, 7–15] years, 35% females). Ninety-nine (30.1%) patients experienced the primary outcome and 74 (22.5%) experienced the secondary outcome during a median follow-up of 6.7 (interquartile range, 2.8–12.5) years. Two-hundred sixteen patients (66.0%) used a nonselective β-blocker (predominantly nadolol [n=140] or propranolol [n=70]) and 111 (33.7%) used a β1-selective β-blocker (predominantly atenolol [n=51], metoprolol [n=33], or bisoprolol [n=19]) as initial β-blocker. Baseline characteristics did not differ. The HRs for both the primary and secondary outcomes were higher for β1-selective compared with nonselective β-blockers (HR, 2.04 [95% CI, 1.31–3.17]; and HR, 1.99 [95% CI, 1.20–3.30], respectively). When assessed separately, the HR for the primary outcome was higher for atenolol (HR, 2.68 [95% CI, 1.44–4.99]), bisoprolol (HR, 3.24 [95% CI, 1.47–7.18]), and metoprolol (HR, 2.18 [95% CI, 1.08–4.40]) compared with nadolol, but did not differ from propranolol. The HR of the secondary outcome was only higher in atenolol compared with nadolol (HR, 2.68 [95% CI, 1.30–5.55]). Conclusions: β1-selective β-blockers were associated with a significantly higher risk for arrhythmic events in symptomatic children with CPVT compared with nonselective β-blockers, specifically nadolol. Nadolol, or propranolol if nadolol is unavailable, should be the preferred β-blocker for treating symptomatic children with CPVT.

Doppler-based methods of estimating the atrioventricular interval are commonly used as a surrogate for the electrical PR in fetuses at risk of conduction abnormalities; however, to date, normal values for the fetal atrioventricular interval and an understanding of the evolution of its components in the late first trimester are lacking. We sought to investigate changes in the fetal atrioventricular interval from the first trimester to 40 weeks gestational age, and to explore functional and electrophysiological events that potentially impact its evolution. We prospectively examined healthy pregnancies by fetal echocardiography from 6 to 40 weeks' gestational age. The atrioventricular interval, heart rate, isovolumic contraction time, and A-wave duration were measured from simultaneous ventricular inflow-outflow Doppler tracings. Regression analysis was used to examine relations with gestational age, and linear relations with heart rate were assessed by Pearson's correlation coefficient. Data were collected in 305 fetuses from 279 pregnancies. Atrioventricular interval demonstrated an inverse relation with heart rate (r = -0.45, p0.0001), dramatically decreasing before 10 weeks and slowly increasing thereafter. Between 6 and 9 weeks, isovolumic contraction time acutely decreased approaching 0, thereafter minimally increasing to term. In contrast, from 6 weeks, the A-wave duration linearly increased through gestation, and negatively correlated with heart rate (r = -0.62, p0.0001). In conclusion, we have established normal measures of the atrioventricular interval from 6 to 40 weeks' gestational age. Before 10 weeks, a prolonged atrioventricular interval in healthy fetuses largely reflects the lengthened isovolumic contraction time which is likely influenced by the evolution of ventricular function and afterload.

OBJECTIVES Neurodevelopmental disability is the most common complication among congenital heart surgery survivors. The Bayley scales are standardized instruments to assess neurodevelopment. The most recent edition (Bayley Scales of Infant and Toddler Development 3rd Edition, Bayley-III) yields better-than-expected scores in typically developing and high-risk infants than the second edition (Bayley Scales of Infant Development 2nd Edition, BSID-II). We compared BSID-II and Bayley-III scores in infants undergoing cardiac surgery. METHODS We evaluated 2198 infants who underwent operations with cardiopulmonary bypass between 1996 and 2009 at 26 institutions. We used propensity score matching to limit confounding by indication in a subset of patients (n = 705). RESULTS Overall, unadjusted Bayley-III motor scores were higher than BSID-II Psychomotor Development Index scores (90.7 ± 17.2 vs 77.6 ± 18.8, P CONCLUSIONS The Bayley-III yielded higher scores than the BSID-II and classified fewer children as severely impaired. The systematic bias towards higher scores with the Bayley-III precludes valid comparisons between early and contemporary cardiac surgery cohorts.

Objectives: This study sought to determine the nature of quinidine use and accessibility in a national network of inherited arrhythmia clinics.Background: Quinidine is an antiarrhythmic med...

Research teams developing biobanks and/or genomic databases must develop policies for the disclosure and reporting of potentially actionable genomic results to research participants. Currently, a broad range of approaches to the return of results exist, with some studies opting for non-disclosure of research results while others follow clinical guidelines for the return of potentially actionable findings from sequencing. In this review, we describe current practices and highlight decisions a research team must make when designing a return of results policy, from informed consent to disclosure practices and clinical validation options. The unique challenges of returning incidental findings in cardiac genes, including reduced penetrance and the lack of clinical screening standards for phenotype-negative individuals are discussed. Lastly, the National Hearts in Rhythm Organization (HiRO) Registry approach is described to provide a rationale for the selective return of field-specific variants to those participating in disease-specific research. Our goal is to provide researchers with a resource when developing a return of results policy tailored for their research program, based on unique factors related to study design, research team composition and availability of clinical resources.

Background Assessing the issues surrounding predictive genetic testing for children at risk of an inherited arrhythmia or cardiomyopathy is complex. The objective of this study was to design and evaluate 4 cardiac decision aids. The decision aids were developed to assist families with a genetic diagnosis of long QT syndrome, hypertrophic cardiomyopathy, dilated cardiomyopathy, or arrhythmogenic right ventricular cardiomyopathy in deciding between predictive genetic testing and cardiac screening for their children. Methods The decision aids were developed with the use of the International Patient Decision Aid Standards framework and revised based on feedback from individuals with lived experience, genetic counsellors, and other health professionals. Results Response to the decision aids was positive, and acceptability and understandability scores were high. Conclusions The decision aids can be used before, during or after a genetic counselling appointment as a resource or to guide discussion. These tools permit a balanced and consistent approach to the decision-making process, with a focus on the importance families place on the advantages and disadvantages of each option.

Background: Implantable cardioverter defibrillators (ICD) are recommended for secondary prevention after sudden cardiac arrest (SCA). The outcomes of pediatric patients receiving an ICD after SCA remain unclear. The objective of this study is to evaluate outcomes, future risk for appropriate shocks, and identify characteristics associated with appropriate ICD therapy during follow-up. Methods: Multicenter retrospective analysis of patients (age ≤21 years) without prior cardiac disease who received an ICD following SCA. Patient/device characteristics, cardiac function, and underlying diagnoses were collected, along with SCA event characteristics. Patient outcomes including complications and device therapies were analyzed. Results: In total, 106 patients were included, median age 14.7 years. Twenty (19%) received appropriate shocks and 16 (15%) received inappropriate shocks (median follow-up 3 years). First-degree relative with SCA was associated with appropriate shocks ( P P =0.015). In patients >2 years from implantation, younger age ( P =0.02) and positive exercise test ( P =0.04) were associated with appropriate shock. Conclusions: The risk of future device therapy is high in pediatric patients receiving an ICD after SCA, irrelevant of underlying disease. Lack of a definitive diagnosis after SCA was not associated with lower risk of subsequent events and does not obviate the need for secondary prophylaxis.

BackgroundSudden cardiac death (SCD) is an unexpected death that occurs within an hour of the onset of symptoms. Hereditary primary electrical disorders account for up to 1/3 of all SCD cases in younger individuals and include conditions such as catecholaminergic polymorphic ventricular tachycardia (CPVT). These disorders are caused by mutations in the genes encoding cardiac ion channels, hence they are known as cardiac channelopathies. We identified a novel variant, T1857I, in the C-terminus of Nav1.5 (SCN5A) linked to a family with a CPVT-like phenotype characterized by atrial tachy-arrhythmias and polymorphic ventricular ectopy occurring at rest and with adrenergic stimulation, and a strong family history of SCD.ObjectiveOur goal was to functionally characterize the novel Nav1.5 variant and determine a possible link between channel gating and clinical phenotype.MethodsWe first used electrocardiogram recordings to visualize the patient cardiac electrical properties. Then, we performed voltage-clamp of transiently transfected CHO cells. Lastly, we used the ventricular/atrial models to visualize gating defects on cardiac excitability.ResultsVoltage-dependences of both activation and inactivation were right-shifted, the overlap between activation and inactivation predicted increased window currents, the recovery from fast inactivation was slowed, there was no significant difference in late currents, and there was no difference in use-dependent inactivation. The O’Hara-Rudy model suggests ventricular after depolarizations and atrial Grandi-based model suggests a slight prolongation of atrial action potential duration.ConclusionWe conclude that T1857I likely causes a net gain-of-function in Nav1.5 gating, which may in turn lead to ventricular after depolarization, predisposing carriers to tachy-arrhythmias.

Introduction: In patients with single ventricle heart disease, prematurity and low weight at the Norwood operation are risk factors for mortality. Reports assessing peri-operative and long-term outcomes of Norwood palliation in patients ≤ 2.5kg are limited. Methods: All patients who underwent Norwood-Sano procedure between 2005-2020 were identified. Patients ≤ 2.5kg at the time of the Norwood operation (cases) were matched 1:3 with patients ≥ 3.0 kg (comparisons) for year of surgery and cardiac diagnosis. Demographic and peri-operative characteristics, survival to hospital discharge and 2-year neurodevelopmental outcomes were compared. Results: Twenty-seven cases (mean±SD weight 2.2±0.3 kg, mean age 15.6±14.1 days at surgery) and 81 comparisons (mean weight 3.5±0.4 kg, mean age 10.9±7.9 days at surgery) were identified. There was no statistically significant difference in the presence of chromosomal abnormalities (7.4% vs. 12.3%, p=0.485), prenatal diagnosis made (88.9% vs. 75.3%, p=0.141), or duration of cardiopulmonary bypass (140.7±65.6 vs. 121.3±42.3 min, p=0.068) between cases and comparisons, respectively. Cases had a longer time to post-operative lactate < 2 mmol/L (33.1±27.5 vs. 17.9±12.2 hours, p Conclusions: Patients ≤ 2.5kg at the time of Norwood-Sano have significantly higher post-operative morbidity and mortality up to 2-year follow-up, and worse 2-year neurodevelopmental motor outcomes. Additional studies are warranted to assess the outcome of alternative therapeutic options in this patient population.

Introduction: Congenital heart disease (CHD) requiring surgical intervention in infancy is associated with impaired neurodevelopmental (ND) outcomes which may be due in part to prenatal insults. Supporting this, we recently found an inverse relationship between 3 rd trimester umbilical artery Doppler-based (UA) pulsatility index (PI=systolic velocity-diastolic velocity/mean velocity) and growth and ND outcomes at 2 years in hypoplastic left heart syndrome and d-transposition of great arteries. In the present study we explore associations between 2 nd and 3 rd trimester UA-PI in all major fetal CHD and 2-year ND outcomes. Methods: We identified all patients with major structural CHD and fetal echocardiography who underwent cardiac surgery and 2-year ND and biometric assessments (Western Canadian Complex Pediatric Therapies Follow-up Program) from 2007-2017 in our program. Eligible surgeries were: bypass < 6 weeks, shunts at < 6 months or isomerisms with surgery at < 12 months. Patients with genetic syndromes were excluded. 2 nd and 3 rd trimester UA-PI z scores were examined for relationships with 2 year Bayley III ND scales. Data is presented as mean (SD). Results: Data from 147 children was analysed (see Table). 2 nd and 3 rd trimester fetal echo was performed at 22.4(3.7) and 34.7(2.9) weeks, with UA-PI z scores of 0.18 (0.3), and 0.51(1.4) and respectively. The Bayley III cognitive, language and motor scores were 93(13), 89(15) and 89(14) for the entire group. Multivariable regression analysis of the entire group and specific subgroups showed an inverse relationship between 3 rd trimester UA-PI and ND domains (see Table). No association was found for 2 nd trimester UA-PI and ND for the whole group and subgroups. Conclusions: Increased 3 rd trimester UA-PI, which could reflect an altered late gestation placental circulation, inversely relates to abnormal 2 year ND. These relationships are most notably observed in SVs and in CHD associated with AOTO.

BackgroundSudden cardiac death (SCD) is an unexpected death that occurs within an hour of the onset of symptoms. Hereditary primary electrical disorders account for up to 1/3 of all SCD cases in younger individuals and include conditions such as catecholaminergic polymorphic ventricular tachycardia (CPVT). These disorders are caused by mutations in the genes encoding cardiac ion channels, hence they are known as cardiac channelopathies. We identified a novel variant, T1857I, in the C-terminus of Nav1.5 (SCN5A) linked to a family with a CPVT-like phenotype characterized by atrial tachy-arrhythmias and polymorphic ventricular ectopy occurring at rest and with adrenergic stimulation, and a strong family history of SCD.ObjectiveOur goal was to functionally characterize the novel Nav1.5 variant and determine a possible link between channel gating and clinical phenotype.MethodsWe first used electrocardiogram recordings to visualize the patient cardiac electrical properties. Then, we performed voltage-clamp of transiently transfected CHO cells. Lastly, we used the ventricular/atrial models to visualize gating defects on cardiac excitability.ResultsVoltage-dependences of both activation and inactivation were right-shifted, the overlap between activation and inactivation predicted increased window currents, the recovery from fast inactivation was slowed, there was no significant difference in late currents, and there was no difference in use-dependent inactivation. The O’Hara-Rudy model suggests ventricular afterdepolarizations and atrial Grandi-based model suggests a slight prolongation of atrial action potential duration.ConclusionWe conclude that T1857I likely causes a net gain-of-function in Nav1.5 gating, which may in turn lead to ventricular afterdepolarization, predisposing carriers to tachy-arrhythmias.

BACKGROUND Implantable cardioverter defibrillator (ICD) lead failures occur at higher rates in pediatric and congenital heart disease (CHD) patients. OBJECTIVE To determine the rate and timing of Riata lead failure in pediatric and CHD patients. METHODS This was a retrospective, multicenter cohort study of pediatric patients and adults with CHD with implantation of a Riata or Riata ST lead between 2002 and 2009. The prevalence and timing of electrical failure and conductor coil externalization (CCE) were determined. RESULTS Fifty-eight patients and 63 leads from seven centers were included. Median (interquartile range [IQR]) age at implant was 14.4 (11.5-18.7) years and median follow-up was 8.7 (7.3-11.1) years. The underlying diagnosis was a primary arrhythmia disorder in 45%, cardiomyopathy in 31%, and CHD in 28% of patients. Electrical failure occurred in 43% and CCE in 16% of leads at median lead ages of 4.7 (3.4-7.5) and 4.3 (3.9-7.0) years, respectively. Median lead survival free from electrical failure or CCE was 7.9 (95% confidence interval, 5.8-10.0) years. Forty-one percent of leads were functional at the end of the follow-up period, and 33% were extracted with a complication rate of 5%. CONCLUSIONS The rate of Riata lead electrical failure was high in children and patients with CHD, while the rate of CCE was comparable with published data. Counseling on lead management should factor in the high rate of electrical failure with considerations for elective replacement.

Background Management of patients with hypoplastic left heart syndrome has benefited from advancements in medical and surgical care. Outcomes have improved, although survival and long‐term functional and cognitive deficits remain a concern. Methods and Results This is a cohort study of all consecutive patients with hypoplastic left heart syndrome undergoing surgical palliation at a single center. We aimed to examine demographic and perioperative factors from each surgical stage for their association with survival and neurocognitive outcomes. A total of 117 consecutive patients from 1996 to 2010 underwent surgical palliation. Seventy patients (60%) survived to the Fontan stage and 68 patients (58%) survived to undergo neurocognitive assessment at a mean ( SD ) age of 56.6 months (6.4 months). Full‐scale, performance, and verbal intelligence quotient, as well as visual‐motor integration mean ( SD ) scores were 86.7 (16.1), 86.3 (15.8), 88.8 (17.2), and 83.2 (14.8), respectively. On multivariable analysis, older age at Fontan, sepsis peri‐Norwood, lowest arterial partial pressure of oxygen postbidirectional cavopulmonary anastomosis, and presence of neuromotor disability pre‐Fontan were strongly associated with lower scores for all intelligence quotient domains. Older age at Fontan and sepsis peri‐Norwood remained associated with lower scores for all intelligence quotient domains in a subgroup analysis excluding patients with disability pre‐Fontan or with chromosomal abnormalities. Conclusions Older age at Fontan and sepsis are among independent predictors of poor neurocognitive outcomes for patients with hypoplastic left heart syndrome . Further studies are required to identify the appropriate age range for Fontan completion, balancing a lower risk of acute and long‐term hemodynamic complications while optimizing long‐term neurocognitive outcomes.

Cascade predictive genetic testing is available for many families as a means to identify individuals at risk of long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT), hypertrophic cardiomyopathy (HCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). The general issue of offering predictive genetic testing to minors has been an area of ethical debate among genetic counselors and other healthcare professionals for many years. An online questionnaire was circulated to four international genetic counseling associations to assess the views of cardiac genetic counselors regarding when to offer predictive genetic testing to children at risk of LQTS, CPVT, HCM, and ARVC. Analysis was both quantitative and qualitative. The study sample comprised 98 respondents. The majority reported that they offer predictive genetic testing before 5 years of age to children at risk of LQTS (83%) and CVPT (75%) and before 10 years of age to children at risk of HCM (66%) or ARVC (70%). Influencing factors included country of practice, clinical setting, and years of experience. The rationale provided for when to offer predictive genetic testing is encompassed by the ethical principles of beneficence, non-maleficence, autonomy, and informed consent. In conclusion, significant practice variation exists among cardiac genetic counselors regarding predictive genetic testing for children at risk of an inherited cardiomyopathy. These variations call for more research in the area to assist with the development of evidence-based guidelines.

Background The implantable cardioverter-defibrillator (ICD) may be associated with a high risk of complications in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT). However, ICDs in this population have not been systematically evaluated. Objective The purpose of this study was to characterize the use and outcomes of ICDs in CPVT. Methods We conducted a systematic review using Embase, MEDLINE, PubMed, and Google Scholar to identify studies that included patients with CPVT who had an ICD. Results Fifty-three studies describing 1429 patients with CPVT were included. In total, 503 patients (35.2%) had an ICD (median age 15.0 years; interquartile range 11.0–21.0 years). Among ICD recipients with a reported medication status, 96.7% were prescribed β-blockers and 13.2% flecainide. Sympathetic denervation was performed in 23.2%. Nearly half of patients received an ICD for primary prevention (47.3%), and 12.8% were prescribed optimal antiarrhythmic therapy. During follow-up, 40.1% had ≥1 appropriate shock, 20.8% experienced ≥1 inappropriate shock, 19.6% had electrical storm, and 7 patients (1.4%) died. An ICD-associated electrical storm was implicated in 4 deaths. Additional complications such as lead failure, endocarditis, or surgical revisions were observed in 96 of 296 patients (32.4%). A subanalysis of the 10 studies encompassing 330 patients with the most detailed ICD-related data showed similar trends. Conclusion In this population with CPVT, ICDs were common and associated with a high burden of shocks and complications. The reliance on primary prevention ICDs, and poor uptake of adjuvant antiarrhythmic therapies, suggests that improved adherence to guideline-directed management could reduce ICD use and harm.

BACKGROUND While youth with Fontan circulation are at increased risk for adverse neurodevelopmental outcomes, not all children encounter these limitations. We sought to evaluate the prevalence and factors associated with "optimal" neurodevelopmental outcomes in 4-6 year old children with Fontan circulation. METHODS AND RESULTS Patients who underwent the Fontan procedure born between September 1996 and December 31, 2015 and followed through the Western Canadian Complex Pediatric Therapies Follow-up Program (CPTFP) were included. All patients underwent a comprehensive neurocognitive assessment between 48-72 months of age. A composite outcome termed optimal neurodevelopmental outcome was defined as the absence of intellectual disability (full-scale intellectual quotient (FSIQ) /=3.25 years, need for AVV intervention, and >/=8 hours to clear lactate) was associated with 7% (1/14) having optimal neurodevelopmental outcomes. CONCLUSION Optimal neurodevelopmental outcome was present in over half of 4-6 year old children with Fontan circulation in this single-center study, with important associated factors identified, including potentially modifiable factors such as younger age at Fontan and lack of concomitant AVV intervention. Multi-center evaluations are needed to further evaluate this previously undefined composite outcome.

OBJECTIVES: The aim of this paper was to investigate whether ventricular arrhythmias in children with catecholaminergic polymorphic ventricular tachycardia (CPVT) show circadian patterns. BACKGROUND: Circadian arrhythmic patterns have been established in long QT, Brugada, and early repolarization, but have not been investigated in CPVT. METHODS: This is a multicenter, retrospective review of pediatric CPVT patients, age

Background Unexplained cardiac arrest (UCA) is rare in children. Despite investigations, the etiology in up to one-half of patients remains unknown. Objective The purpose of this study was to assess the management and outcomes of pediatric UCA survivors through the Canadian Pediatric Heart Rhythm Network. Methods A retrospective case series of children (age 1–19 years) who presented with UCA between January 1, 2004, and November 1, 2017, was conducted. Patients with known heart disease pre-UCA were excluded. UCA details, investigations, genetic test results, treatment, implantable cardioverter–defibrillator (ICD) data, subsequent diagnoses, and family screening data were collected. Results Forty-six patients (61% male) were survivors of sudden unexpected death and met inclusion criteria at 8 participating sites. Median age at UCA was 13.8 years (interquartile range [IQR] 9–16 years). Baseline retrievable investigations included electrocardiogram (96%), echocardiogram (85%), exercise stress test (73%), and cardiac magnetic resonance imaging (57%). The presumed etiology for the UCA was identified in 24 (52%), mainly long QT syndrome or catecholaminergic polymorphic ventricular tachycardia. Genetic testing was performed in 33 of 46 (72%), with pathogenic/likely pathogenic variants identified in 13 of 33 (39%) and variants of uncertain significance in 8 of 33 (24%). ICDs were implanted in 35 of 46 (76%). Over median follow-up of 36 months (IQR 17–57 months), 8 of 35 had arrhythmia events captured on device interrogation. Families of 26 of 46 patients(57%) underwent screening, leading to a cardiac diagnosis in 6 of 26 families. Conclusion A cause for UCA was not identified in nearly 50% of patients despite extensive investigations, including cascade screening. A large proportion (75%) of ICD shocks occurred in patients without a diagnosis.

Post-operative length of stay (LOS) is an important metric for both healthcare providers and patients and their families. Predicting LOS is a challenge as it is sensitive to multitudinous patient and system factors. All subjects undergoing a Fontan from 1996–2016 who survived to hospital discharge were included. Details about the pre-operative status, operative conduct, and post-operative course of each patient were obtained. The association between patient characteristics and post-Fontan LOS were determined using stepwise multivariable regression models. Of 320 subjects who underwent a Fontan, 314 (98.1%) survived to hospital discharge. Median age at Fontan was 3.3 years (IQR 2.8, 4.0) and the most common underlying diagnosis was hypoplastic left heart syndrome (106, 33.8%). Median post Fontan LOS was 11 days (IQR 8, 17). Univariable risk factors for longer LOS included number of previous surgeries, post-Glenn LOS, cardiopulmonary bypass time, post-operative chylothorax, and failure to extubate in the operating room (all p