Current State of Cardiac Implantable Electronic Device Remote Monitoring in Pediatrics and Congenital Heart Disease: A PACES-Sponsored Quality Improvement Initiative.

Cardiac implantable electronic device (CIED) remote transmissions are an integral part of longitudinal follow-up in pediatric and adult congenital heart disease (ACHD) patients. To evaluate baseline CIED remote monitoring (RM) data among pediatric and ACHD centers prior to implementation of a Pediatric and Congenital Electrophysiology  Society (PACES)-sponsored quality improvement (QI) project. This is a cross-sectional study of baseline CIED RM. Centers self-reported baseline data: individual center RM compliance was defined as high if there was > 80% achievement and low if < 50%. A total of 22 pediatric centers in the USA and Australia submitted baseline data. Non-physicians were responsible for management of the RM program in most centers: registered nurse (36%), advanced practice provider (27%), combination (23%), and third party (9%). Fifteen centers (68%) reported that > 80% of their CIED patients are enrolled in RM and only two centers reported < 50% participation. 36% reported high compliance of device transmission within 14 days of implant and 77% of centers reported high compliance of CIED patients enrolled in RM. The number of centers achieving high compliance differed by device type: 36% for pacemakers, 50% for ICDs, and 55% for Implantable Cardiac Monitors (ICM). All centers reported at least 50% adherence to recommended follow-up for PM and ICD, with 23% low compliance rate for ICMs. Based on this cross-sectional survey of pediatric and ACHD centers, compliance with CIED RM is sub-optimal. The PACES-sponsored QI initiative will provide resources and support to participating centers and repeat data will be evaluated after PDSA cycles.

Inconsistent discharge diagnoses for young cardiac arrest episodes: insights from a statewide registry.

BACKGROUND: Administrative coding of out-of-hospital cardiac arrest (OHCA) is heterogeneous, with the prevalence of noninformative diagnoses uncertain. AIM: To characterize the prevalence and type of non-informative diagnoses in a young cardiac arrest population. METHODS: Hospital discharge diagnoses provided to a statewide OHCA registry were characterised as either 'informative' or 'noninformative.' Informative diagnoses stated an OHCA had occurred or defined OHCA as occurring due to coronary artery disease, cardiomyopathy, channelopathy, definite noncardiac cause, or no known cause. Noninformative diagnoses were blank, stated presenting cardiac rhythm only, provided irrelevant information or presented a complication of the OHCA as the main diagnosis. Characteristics of patients receiving informative versus noninformative diagnoses were compared. RESULTS: Of 1479 patients with OHCA aged 1 to 50 years, 290 patients were admitted to 15 hospitals. Ninety diagnoses (31.0%) were noninformative (arrest rhythm = 50, blank = 21, complication = 10 and irrelevant = 9). Two hundred diagnoses (69.0%) were informative (cardiac arrest = 84, coronary artery disease = 54, noncardiac diagnosis = 48, cardiomyopathy = 8, arrhythmia disorder = 4 and unascertained = 2). Only 10 diagnoses (3.5%) included both OHCA and an underlying cause. Patients receiving a noninformative diagnosis were more likely to have survived OHCA or been referred for forensic assessment (P = 0.011) and had longer median length of stay (9 vs 5 days, P = 0.0019). CONCLUSION: Almost one third of diagnoses for young patients discharged after an OHCA included neither OHCA nor any underlying cause. Underestimating the burden of OHCA impacts ongoing patient and at-risk family care, data sampling strategies, international statistics and research funding.

Patterns of Electrocardiographic Abnormalities in Children with Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM), a common cardiomyopathy in children, is an important cause of morbidity and mortality. Early recognition and appropriate management are important. An electrocardiogram (ECG) is often used as a screening tool in children to detect heart disease. The ECG patterns in children with HCM are not well described.ECGs collected from an international cohort of children, and adolescents (≤ 21 years) with HCM were reviewed. 482 ECGs met inclusion criteria. Age ranged from 1 day to 21 years, median 13 years. Of the 482 ECGs, 57 (12%) were normal. The most common abnormalities noted were left ventricular hypertrophy (LVH) in 108/482 (22%) and biventricular hypertrophy (BVH) in 116/482 (24%) Of the patients with LVH/BVH (n = 224), 135 (60%) also had a strain pattern (LVH in 83, BVH in 52). Isolated strain pattern (in the absence of criteria for hypertrophy) was seen in 43/482 (9%). Isolated pathologic Q waves were seen in 71/482 (15%). Pediatric HCM, 88% have an abnormal ECG. The most common ECG abnormalities were LVH or BVH with or without strain. Strain pattern without hypertrophy and a pathologic Q wave were present in a significant proportion (24%) of patients. Thus, a significant number of children with HCM have ECG abnormalities that are not typical for "hypertrophy". The presence of the ECG abnormalities described above in a child should prompt further examination with an echocardiogram to rule out HCM.

Prevalence of Multiple Causes of Death Within Young and Middle-Aged People Experiencing Sudden Cardiac Arrest.

BACKGROUND: Multiple causes of death are increasingly reported, particularly in older populations. Rates of multiple causes of young sudden death have not been quantified. METHOD: The End Unexplained Cardiac Death (EndUCD) registry was utilised to identify cases of young sudden death (aged 1-50 years) referred for forensic assessment from April 2019 to April 2022. Causes of death were coded according to whether one or more underlying causes of death were identified. Patients were compared according to the number of causes of death, with significant predictors assessed using logistic regression analysis. RESULTS: 1,085 cases of sudden death were identified. 263 (24.2%) cases had more than one competing cause of their sudden death. The most common multi-causal associations identified were dual non-cardiac causes of the sudden death (n=68), cardiomyopathy with non-cardiac event (n=64) and coronary artery disease with non-cardiac cause (n=63). Multi-causal death was more common in those undergoing comprehensive autopsy examination (95.8% vs 77.6%, p<0.0001), and in the setting of higher body mass index (median 31.3 kg/m2 vs 29.9 kg/m2, p=0.01), older age (44.3 years vs 41.4 years, p<0.0001), non-ventricular cardiac arrest rhythm (93.2% vs 87.3%, p=0.009), and smoking (22.8% vs 14.2%, p=0.001). The strongest predictor of multiple pathologies was comprehensive autopsy examination compared with external inspection, full-body post-mortem computed tomography and review of ancillary documentation and investigations (odds ratio 6.49, 95% confidence interval 3.47-12.14). CONCLUSIONS: One-quarter of young sudden deaths have more than one underlying cause, highlighting the value of comprehensive investigations including autopsy. Awareness of the complexity of young sudden death is important, along with multidisciplinary involvement to ensure all contributors to death are identified.

Causes, circumstances, and potential preventability of cardiac arrest in the young: insights from a state-wide clinical and forensic registry.

AIMS: The causes, circumstances, and preventability of young sudden cardiac arrest remain uncertain. METHODS AND RESULTS: A prospective state-wide multi-source registry identified all out-of-hospital cardiac arrests (OHCAs) in 1-50 year olds in Victoria, Australia, from 2019 to 2021. Cases were adjudicated using hospital and forensic records, clinic assessments and interviews of survivors and family members. For confirmed cardiac causes of OHCA, circumstances and cardiac history were collected. National time-use data was used to contextualize circumstances. 1319 OHCAs were included. 725 (55.0%) cases had a cardiac aetiology of OHCA, with coronary disease (n = 314, 23.8%) the most common pathology. Drug toxicity (n = 226, 17.1%) was the most common non-cardiac cause of OHCA and the second-most common cause overall. OHCAs were most likely to occur in sleep (n = 233, 41.2%). However, when compared to the typical Australian day, OHCAs occurred disproportionately more commonly during exercise (9% of patients vs. 1.3% of typical day, P = 0.018) and less commonly while sedentary (39.6 vs. 54.6%, P = 0.047). 38.2% of patients had known standard modifiable cardiovascular risk factors. 77% of patients with a cardiac cause of OHCA had not reported cardiac symptoms nor been evaluated by a cardiologist prior to their OHCA. CONCLUSION: Approximately half of OHCAs in the young have a cardiac cause, with coronary disease and drug toxicity dominant aetiologies. OHCAs disproportionately occur during exercise. Of patients with cardiac cause of OHCA, almost two-thirds have no standard modifiable cardiovascular risk factors, and more than three-quarters had no prior warning symptoms or interaction with a cardiologist.

Higher rates but similar causes of young out-of-hospital cardiac arrest in rural Australian patients.

OBJECTIVE: To determine whether young rural Australians have higher rates or different underlying causes of out-of-hospital cardiac arrest (OHCA). DESIGN: A case-control design identified patients experiencing an OHCA, then compared annual OHCA rates and underlying causes in rural versus metropolitan Victoria. OHCA causes were defined as either cardiac or non-cardiac, with specific aetiologies including coronary disease, cardiomyopathy, unascertained cause of arrest, drug toxicity, respiratory event, neurological event and other cardiac and non-cardiac. For OHCAs with confirmed cardiac aetiology, cardiovascular risk profiles were compared. SETTING: A state-wide prospective OHCA registry (combining ambulance, hospital and forensic data) in the state of Victoria, Australia (population 6.5 million). PARTICIPANTS: Victorians aged 1-50 years old experienced an OHCA between April 2019 and April 2020. MAIN OUTCOME MEASURES: Rates and underlying causes of OHCA in young rural and metropolitan Victorians. RESULTS: Rates of young OHCA were higher in rural areas (OHCA 22.5 per 100 000 rural residents vs. 13.4 per 100 000 metropolitan residents, standardised incidence ratio 168 (95% CI 101-235); confirmed cardiac cause of arrest 12.1 per 100 000 rural residents versus 7.5 per 100 000 metropolitan residents, standardised incidence ratio 161 (95% CI 71-251). The underlying causation of the OHCA and cardiovascular risk factor burden did not differ between rural and metropolitan areas. CONCLUSION: Higher rates of OHCA occur in young rural patients, with standardised incidence ratio of 168 compared to young metropolitan residents. Rural status did not influence causes of cardiac arrest or known cardiovascular risk factor burden in young patients experiencing OHCA.

Review of atrial fibrillation for the general paediatrician.

Paediatric atrial fibrillation (AF) is an infrequent entity in the absence of congenital heart disease as children are unlikely to have the structural and functional changes in their myocardium to sustain the arrhythmia. Any child presenting with this arrhythmia needs to be carefully evaluated for concealed cardiac pathology such as cardiomyopathy or inherited arrhythmia syndromes. AF leading to a haemodynamically unstable patient is rare and should prompt synchronised cardioversion, while stable patients can be discussed with a paediatric cardiologist. Tachycardia-induced cardiomyopathy and thromboembolism are possible complications of sustained AF and anticoagulation is usually indicated to prevent the latter. Risk of AF increases with age and body mass index. Obesity and athletics are known risk factors and recurrence can be seen even in the absence of any identifiable underlying pathology.

The End Unexplained Cardiac Death (EndUCD) Registry for Young Australian Sudden Cardiac Arrest.

In 2019, the first multi-source registry of sudden cardiac arrest and death for patients aged 1-50 years launched in Victoria, Australia. Sudden cardiac arrest (SCA) affects approximately fifteen hundred younger Victorians per year. The End Unexplained Cardiac Death (EndUCD) Registry enrols SCA/death (D) cases aged 1-50 years, providing family screening, access to psychological support through clinical sites and creating a genetic biorepository for whole-genome sequencing. The registry will support clear pathways of cardiac assessment, epidemiological profiling and routine family screening and psychological support.

Can post-mortem coronary artery calcium scores aid diagnosis in young sudden death?

This study sought to explore the feasibility and utility of post-mortem coronary artery calcium (CAC) scoring in identifying patients with ischemic heart disease as cause of sudden death. 100 deceased patients aged 18-50 years underwent post-mortem examination in the setting of sudden death. At post-mortem, fifty cases were determined to have ischemic heart disease, and fifty had death attributed to trauma or unascertained causes. The CAC score was calculated in a blinded manner from post-mortem CTs performed on all cases. CAC scores were assessable in 97 non-decomposed cases (feasibility 97%). The median CAC score was 88 Agatston units [IQR 0-286] in patients deceased from ischemic heart disease vs 0 [IQR 0-0] in patients deceased from other causes (p < 0.0001). Presence of any coronary calcification differed significantly between ischemic heart disease and non-ischemic groups (adjusted odds ratio 10.7, 95% CI 3.2-35.5). All cases with a CAC score > 100 (n = 22) had ischemic heart disease as the cause of death. Fifteen cases had a CAC score of zero but severe coronary disease at post-mortem examination. Post-mortem CAC scoring is highly feasible. An elevated CAC score in cases 18-50 years old with sudden death predicts ischemic heart disease at post-mortem examination. However, a CAC score of zero does not exclude significant coronary artery disease. Post-mortem CAC score may be considered as a further assessment tool to help predict likely cause of death when there is an objection to or unavailability of post-mortem examination.

50 Years of Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) - Time to Explore the Dark Side of the Moon.

Despite significant progress in understanding catecholaminergic polymorphic ventricular tachycardia (CPVT), there are still multiple uncertainties and gaps in our knowledge. Like the dark side of the moon, we cannot see them directly. Unfortunately, clinicians must make diagnostic and therapeutic decisions without solid evidence. Instead of summarising the current state of science and reiterating the guidelines, we review difficulties in understanding the disease mechanism, diagnosis and therapy. Highlighting these truths helps to avoid misconceptions, think clearly about our patients and direct future research efforts. It has become clear that CPVT encompasses more than just uniformly expressed ryanodine receptor mutations leading to bidirectional ventricular tachycardia, rather it is a disease caused by different genetic mutations, overlapping with other entities and possibly affecting not only the heart. Treatment in addition to beta blockers is often necessary: flecainide and left cardiac sympathetic denervation are therapies that come before consideration of defibrillator implantation and new treatment options are on the horizon.

Position Statement on the Management of Cardiac Electrophysiology and Cardiac Implantable Electronic Devices in Australia During the COVID-19 Pandemic: A Living Document.

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time.

Management of People With a Fontan Circulation: a Cardiac Society of Australia and New Zealand Position statement.

The Fontan circulation describes the circulatory state resulting from an operation in congenital heart disease where systemic venous return is directed to the lungs without an intervening active pumping chamber. As survival increases, so too does recognition of the potential health challenges. This document aims to allow clinicians, people with a Fontan circulation, and their families to benefit from consensus agreement about management of the person with a Fontan circulation. The document was crafted with input from a multidisciplinary group of health care providers as well as individuals with a Fontan circulation and families. It is hoped that the shared common vision of long-term wellbeing will continue to drive improvements in care and quality of life in this patient population and eventually translate into improved survival. KEYPOINTS.

Impact of Obesity on Left Ventricular Thickness in Children with Hypertrophic Cardiomyopathy.

Obesity is associated with additional left ventricular hypertrophy (LVH) in adults with hypertrophic cardiomyopathy (HCM). It is not known whether obesity can lead to further LVH in children with HCM. Echocardiographic LV dimensions were determined in 504 children with HCM. Measurements of interventricular septal thickness (IVST) and posterior wall thickness (PWT), and patients' weight and height were recorded. Obesity was defined as a body mass index (BMI) ≥ 99th percentile for age and sex. IVST data was available for 498 and PWT data for 484 patients. Patient age ranged from 2 to 20 years (mean ± SD, 12.5 ± 3.9) and 340 (68%) were males. Overall, patient BMI ranged from 7 to 50 (22.7 ± 6.1). Obesity (BMI 18-50, mean 29.1) was present in 140 children aged 2-19.6 (11.3 ± 4.1). The overall mean IVST was 20.5 ± 9.6 mm and the overall mean PWT was 11.0 ± 8.4 mm. The mean IVST in the obese patients was 21.6 ± 10.0 mm and mean PWT was 13.3 ± 14.7 mm. The mean IVST in the non-obese patients was 20.1 ± 9.5 mm and mean PWT was 10.4 ± 4.3 mm. Obesity was not significantly associated with IVST (p = 0.12), but was associated with increased PWT (0.0011). Obesity is associated with increased PWT but not IVST in children with HCM. Whether obesity and its impact on LVH influences clinical outcomes in children with HCM needs to be studied.

The clinical and genetic spectrum of catecholaminergic polymorphic ventricular tachycardia: findings from an international multicentre registry.

Aims: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an ion channelopathy characterized by ventricular arrhythmia during exertion or stress. Mutations in RYR2-coded Ryanodine Receptor-2 (RyR2) and CASQ2-coded Calsequestrin-2 (CASQ2) genes underlie CPVT1 and CPVT2, respectively. However, prognostic markers are scarce. We sought to better characterize the phenotypic and genotypic spectrum of CPVT, and utilize molecular modelling to help account for clinical phenotypes. Methods and results: This is a Pediatric and Congenital Electrophysiology Society multicentre, retrospective cohort study of CPVT patients diagnosed at <19 years of age and their first-degree relatives. Genetic testing was undertaken in 194 of 236 subjects (82%) during 3.5 (1.4-5.3) years of follow-up. The majority (60%) had RyR2-associated CPVT1. Variant locations were predicted based on a 3D structural model of RyR2. Specific residues appear to have key structural importance, supported by an association between cardiac arrest and mutations in the intersubunit interface of the N-terminus, and the S4-S5 linker and helices S5 and S6 of the RyR2 C-terminus. In approximately one quarter of symptomatic patients, cardiac events were precipitated by only normal wakeful activities. Conclusion: This large, multicentre study identifies contemporary challenges related to the diagnosis and prognostication of CPVT patients. Structural modelling of RyR2 can improve our understanding severe CPVT phenotypes. Wakeful rest, rather than exertion, often precipitated life-threatening cardiac events.

Is cardiac rhabdomyoma a feature of Birt Hogg Dubé syndrome?

We report on a child with two cardiac rhabdomyomas. Initially, a diagnosis of Tuberous Sclerosis Complex (TSC) syndrome was suspected, although this could neither be confirmed clinically nor genetically. Coincidentally, Birt Hogg Dubé syndrome (BHD) had been previously diagnosed in members of the extended family; this prompted a diagnostic re-evaluation of the child who was found to have the known family FLCN mutation. We recommend consideration of cardiac rhabdomyomas as part of the clinical BHD spectrum.

Successful implantation of a dual-chamber pacemaker in an ELBW infant for long QT syndrome.

Long QT syndromes encompass the most prevalent group of ion channelopathies. Long QT syndromes are predominantly familial and predispose the affected individual to ventricular arrhythmias and sudden death. Permanent pacemaker insertion for long QT syndrome is discouraged apart from younger patients exhibiting 2:1 atrioventricular block. However, permanent pacemaker insertion is a relatively common procedure in neonates with atrioventricular block, and dual-chamber permanent pacemaker insertion in low birth weight infants is challenging. We describe the management of long QT syndrome - type 2 - presenting in an extremely preterm neonate including epicardial, dual-chamber permanent pacemaker insertion.

Prevalence of atrial septal defects and patent foramen ovale in a cohort of sudden cardiac death patients undergoing autopsy.

BACKGROUND: Patent foramen ovale (PFO) and atrial septal defects (ASD) have been described in up to 30 % of subjects in autopsy series but contemporary data are scarce. It is important to confirm the prevalence of ASD/PFO in the general population given the potential associated stroke risk and the increasing availability of intervention via PFO closure. METHODS: A state-wide prospective out-of-hospital cardiac arrest registry (OHCA) identified all patients aged 1 to 50 years who experienced OHCA in Victoria, Australia from April 2019 to April 2022 and subsequently underwent autopsy with a cardiac cause of death identified. Autopsy was performed including visual description of any ASD and identification of probe patency of foramen ovale. RESULTS: A total of 517 patients underwent autopsy in the setting of sudden cardiac death; 36 patients (6.9 %) had a probe-patent foramen ovale, 2 patients (0.4 %) had secundum ASD, and 2 patients (0.4 %) had both a PFO and ASD (1 of whom had undergone percutaneous repair of both lesions). Twelve patients (2.3 %) had a prior history of cerebrovascular accident either recorded on medical history or detected on neuropathological examination; however none of these patients had a PFO or ASD. CONCLUSIONS: The combined rate of PFO and ASD in a cohort of 517 patients undergoing autopsy was 7.9 %. None of these patients had experienced a cerebrovascular accident. This rate of PFOs appears lower than earlier reports and raises the possibility that the relative risk of an associated stroke could be higher than previously estimated.

Electrical storm in children.

Electrical storm (ES) presents a difficult management problem that has predominantly been described in adults and there are limited published data relating to children. We set out to characterize ES in children to assist management based on published literature and own institutional experience. We retrospectively analyzed the records of children presenting with ES to our institution between July 2001 and July 2011 and conducted a systematic literature review. Four children were identified (median age: 5.7 years, range: 3.3-9.6 years, one male). Each ES was of different character and different management strategies were used. All patients were alive at a median follow-up of 5.7 years and all had received implantable cardioverter-defibrillators. Two patients were felt to have catecholaminergic polymorphic ventricular tachycardia, one possible long QT syndrome and one the "short-coupled" variant of torsades de pointes. At least three of our four patients had possible iatrogenic contribution to their ES. Forty-seven cases of ES in children with variable management strategies were identified from the published literature. ES is a rare medical emergency in children with multiple etiologies requiring individualized management.