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.

Impact of Fontan Fenestration on Adverse Cardiovascular Outcomes: A Multicentre Study

BACKGROUND

Fenestrating a Fontan baffle has been associated with improved perioperative outcomes in patients with univentricular hearts. However, longer-term potential adverse effects remain debated. We sought to assess the impact of a fenestrated Fontan baffle on adverse cardiovascular events including all-cause mortality, cardiac transplantation, atrial arrhythmias, and thromboemboli.

METHODS

A multicentre North American retrospective cohort study was conducted on patients with total cavopulmonary connection Fontan baffle, with and without fenestration. All components of the composite outcome were independently adjudicated. Potential static and time-varying confounders were taken into consideration, along with competing risks.

RESULTS

A total of 407 patients were followed for 10.4 (7.1-14.4) years; 70.0% had fenestration of their Fontan baffle. The fenestration spontaneously closed or was deliberately sealed in 79.9% of patients a median of 2.0 years after Fontan completion. In multivariable analysis in which a persistent fenestration was modelled as a time-dependent variable, an open fenestration did not confer a higher risk of the composite outcome (hazard ratio, 1.18; 95% confidence interval, 0.71-1.97; P = 0.521). In secondary analyses, an open fenestration was not significantly associated with components of the primary outcome: that is, mortality or transplantation, atrial arrhythmias, or thromboemboli. However, sensitivity analyses to assess the possible range of error resulting from imprecise dates for spontaneous fenestration closures could not rule out significant associations between an open fenestration and atrial arrhythmias or thromboemboli.

CONCLUSIONS

In this multicentre study, no significant association was identified between an open fenestration in the Fontan baffle and major adverse cardiovascular events.

Assessing the applicability and appropriateness of ChatGPT in answering clinical pharmacy questions

OBJECTIVES

Clinical pharmacists rely on different scientific references to ensure appropriate, safe, and cost-effective drug use. Tools based on artificial intelligence (AI) such as ChatGPT (Generative Pre-trained Transformer) could offer valuable support. The objective of this study was to assess ChatGPT's capacity to correctly respond to clinical pharmacy questions asked by healthcare professionals in our university hospital.

MATERIAL AND METHODS

ChatGPT's capacity to respond correctly to the last 100 consecutive questions recorded in our clinical pharmacy database was assessed. Questions were copied from our FileMaker Pro database and pasted into ChatGPT March 14 version online platform. The generated answers were then copied verbatim into an Excel file. Two blinded clinical pharmacists reviewed all the questions and the answers given by the software. In case of disagreements, a third blinded pharmacist intervened to decide.

RESULTS

Documentation-related issues (n=36) and drug administration mode (n=30) were preponderantly recorded. Among 69 applicable questions, the rate of correct answers varied from 30 to 57.1% depending on questions type with a global rate of 44.9%. Regarding inappropriate answers (n=38), 20 were incorrect, 18 gave no answers and 8 were incomplete with 8 answers belonging to 2 different categories. No better answers than the pharmacists were observed.

CONCLUSIONS

ChatGPT demonstrated a mitigated performance in answering clinical pharmacy questions. It should not replace human expertise as a high rate of inappropriate answers was highlighted. Future studies should focus on the optimization of ChatGPT for specific clinical pharmacy questions and explore the potential benefits and limitations of integrating this technology into clinical practice.

Cardiovascular Outcomes in Fontan Patients With Right vs Left Univentricular Morphology: A Multicenter Study

Background

There is a paucity of data on long-term outcomes after Fontan palliation in patients with a dominant morphological univentricular right (uRV) vs left (uLV) ventricle.

Objectives

The purpose of this study was to compare the incidence of atrial arrhythmias, thromboembolic events, cardiac transplantation, and death following Fontan palliation in patients with uRV vs uLV.

Methods

The Alliance for Adult Research in Congenital Cardiology conducted a multicenter retrospective cohort study on patients with total cavopulmonary connection Fontan palliation across 12 centers in North America. All components of the composite outcome, that is, atrial arrhythmias, thromboembolic events, cardiac transplantation, and death, were reviewed and classified by a blinded adjudicating committee. Time-to-event analyses were performed that accounted for competing risks.

Results

A total of 384 patients were followed for 10.5 ± 5.9 years. The composite outcome occurred in 3.7 vs 1.7 cases per 100 person-years for uRV (N = 171) vs uLV (N = 213), respectively (P < 0.001). In multivariable analyses, uRV conferred a >2-fold higher risk of the composite outcome (HR: 2.17, 95% CI: 1.45-3.45, P < 0.001). In secondary analyses of components of the primary outcome, uRV was significantly associated with a greater risk of cardiac transplantation or death (HR: 9.09, 95% CI: 2.17-38.46, P < 0.001) and atrial arrhythmias (HR: 2.17, 95% CI: 1.20-4.00, P = 0.010) but not thromboembolic events (HR: 1.64, 95% CI: 0.86-3.16, P = 0.131).

Conclusions

Fontan patients with uRV vs uLV morphology have a higher incidence of adverse cardiovascular events, including atrial arrhythmia, cardiac transplantation, and all-cause mortality.

A commentary on the healthcare transition policy landscape for youth with disabilities or chronic health conditions, the need for an inclusive and equitable approach, and recommendations for change in Canada

There is a growing number of youth with healthcare needs such as disabilities or chronic health conditions who require lifelong care. In Canada, transfer to the adult healthcare system typically occurs at age 18 and is set by policy regardless of whether youth and their families are ready. When the transition to adult services is suboptimal, youth may experience detrimental gaps in healthcare resulting in increased visits to the emergency department and poor healthcare outcomes. Despite the critical need to support youth with disabilities and their families to transition to the adult healthcare system, there is limited legislation to ensure a successful transfer or to mandate transition preparation in Canada. This advocacy and policy planning work was conducted in partnership with the Patient and Family Advisory Council (PFAC) within the CHILD-BRIGHT READYorNot™ Brain-Based Disabilities (BBD) Project and the CHILD-BRIGHT Policy Hub. Together, we identified the need to synthesize and better understand existing policies about transition from pediatric to adult healthcare, and to recommend solutions to improve healthcare access and equity as Canadian youth with disabilities become adults. In this perspective paper, we will report on a dialogue with key informants and make recommendations for change in healthcare transition policies at the healthcare/community, provincial and/or territorial, and/or national levels.

Navigating Arrhythmias in Tetralogy of Fallot Throughout the Lifespan: A Case-based Review

Arrhythmias are a common complication associated with tetralogy of Fallot (ToF), one of the most prevalent forms of congenital heart disease. As illustrated by this case-based review, various forms of arrhythmias can be encountered across the lifespan of patients with ToF, from infancy to older adulthood. These include atrioventricular block, junctional ectopic tachycardia, and atrial and ventricular arrhythmias. Arrhythmias have important implications on the health and quality of life of patients with ToF and require treatment by caregivers with dedicated expertise. The choice of pharmacologic and/or interventional therapies to alleviate symptoms, avoid complications, and mitigate risks depends in part on the type, severity, and frequency of the arrhythmia, as well as on the particularities of individual clinical scenarios. Preventing, monitoring for, and managing arrhythmias are an integral component of the care of patients with ToF throughout their lifespan that is critical to optimizing health outcomes.

Transition from Paediatric to adult health services: Aspirations and practices of human flourishing

BACKGROUND

Transition from paediatric to adult care is challenging for youths with a chronic condition. Most transition programmes place high value in autonomy and independence. We undertook a qualitative study to: (1) identify the needs and aspirations of youths and (2) better understand the well-being and flourishing of youths.

METHODS

Semi-structured interviews were conducted with youths, parents of youths and healthcare professionals recruited from four clinics. Thematic analysis focused on: (1) perceptions of transition; (2) key aspects of human flourishing during transition; and (3) salient concerns with respect to the transition and dimensions of human flourishing.

RESULTS

54 interviews were conducted. Perceptions of transition clustered around: (1) apprehension about adult care; (2) lack of clarity about the transition process; (3) emotional attachment to paediatric healthcare professionals; (4) the significance of the coinciding transition into adulthood. Fourteen salient concerns (e.g., Knowledge and information about the transition, Parental involvement in healthcare) were identified with corresponding recommendations. Salient concerns related to important dimensions of human flourishing (e.g., environmental mastery, autonomy).

DISCUSSION AND CONCLUSION

The flourishing of youths is affected by suboptimal transition practices. We discuss the implications of our findings for environmental mastery, contextual autonomy, and the holistic and humanistic aspects of transition.

Perceived self-efficacy and empowerment in patients at increased risk of sudden cardiac arrest

Background

The role of multidisciplinary clinics for psychosocial care is increasingly recognized for those living with inherited cardiac conditions (ICC). In Canada, access to healthcare providers differ between clinics. Little is known about the relationship between access to specialty care and a patient's ability to cope with, and manage their condition.

Methods

We leveraged the Hearts in Rhythm Organization (HiRO) to conduct a cross-sectional, community-based survey of individuals with ICC and their family members. We aimed to describe access to services, and explore the relationships between participants' characteristics, cardiac history and self-reported health status and self-efficacy (GSE: General Self-Efficacy Scale) and empowerment (GCOS-24: Genetic Counseling Outcome Scale).

Results

We collected 235 responses from Canadian participants in 10 provinces and territories. Overall, 63% of participants reported involvement of a genetic counsellor in their care. Access to genetic testing was associated with greater empowerment [mean GCOS-24: 121.14 (SD = 20.53) vs. 105.68 (SD = 21.69); p = 0.004]. Uncertain genetic test results were associated with lower perceived self-efficacy (mean GSE: uncertain = 28.85 vs. positive = 33.16, negative = 34.13; p = 0.01). Low global mental health scores correlated with both lower perceived self-efficacy and empowerment scores, with only 11% of affected participants reporting involvement of psychology services in their care.

Conclusion

Differences in resource accessibility, clinical history and self-reported health status impact the perceived self-efficacy and empowerment of patients with ICC. Future research evaluating interventions to improve patient outcomes is recommended.

Identification and in-silico characterization of splice-site variants from a large cardiogenetic national registry

Splice-site variants in cardiac genes may predispose carriers to potentially lethal arrhythmias. To investigate, we screened 1315 probands and first-degree relatives enrolled in the Canadian Hearts in Rhythm Organization (HiRO) registry. 10% (134/1315) of patients in the HiRO registry carry variants within 10 base-pairs of the intron-exon boundary with 78% (104/134) otherwise genotype negative. These 134 probands were carriers of 57 unique variants. For each variant, American College of Medical Genetics and Genomics (ACMG) classification was revisited based on consensus between nine in silico tools. Due in part to the in silico algorithms, seven variants were reclassified from the original report, with the majority (6/7) downgraded. Our analyses predicted 53% (30/57) of variants to be likely/pathogenic. For the 57 variants, an average of 9 tools were able to score variants within splice sites, while 6.5 tools responded for variants outside these sites. With likely/pathogenic classification considered a positive outcome, the ACMG classification was used to calculate sensitivity/specificity of each tool. Among these, Combined Annotation Dependent Depletion (CADD) had good sensitivity (93%) and the highest response rate (131/134, 98%), dbscSNV was also sensitive (97%), and SpliceAI was the most specific (64%) tool. Splice variants remain an important consideration in gene elusive inherited arrhythmia syndromes. Screening for intronic variants, even when restricted to the ±10 positions as performed here may improve genetic testing yield. We compare 9 freely available in silico tools and provide recommendations regarding their predictive capabilities. Moreover, we highlight several novel cardiomyopathy-associated variants which merit further study.

Impacts of climate change on wind energy potential in Australasia and South-East Asia following the Shared Socioeconomic Pathways

Wind energy is poised to play a major role in the energy transition. Fluctuations in global atmospheric circulation are expected as a result of climate change, and wind projections based on the most up-to-date scenarios of climate change, the Shared Socioeconomic Pathways (SSPs), anticipate significant changes in wind energy potential in many regions; so far, these changes have not been studied in Southeastern Asia and Australasia, a region with notable wind energy potential. This work investigates the evolution of wind power density and its temporal variability considering the latest scenarios of climate change, the SSPs. More specifically, two scenarios are considered, SSP2-4.5 and SSP5-8.5, corresponding to moderate and high emissions, respectively. As many as 18 global climate models are considered and compared against past-present data, and those that perform best are retained to build a large multi-model ensemble. The results show that projected changes in mean wind power density at the end of the 21st century are of little significance (typically below 5 %); nevertheless, this value can be far surpassed locally. In certain areas (e.g., Vietnam, Borneo) and seasons, remarkable changes in wind power density (exceeding 150 %) are anticipated. Typically, mean values and temporal variability changes are greater in the high-emissions scenario, however, seasonal variability is projected to be more pronounced in the moderate-emissions scenario. These effects of climate change on wind energy potential must be taken into account in the development of wind power in the region, for they will affect the energy production and, therefore, the economic viability of wind farms - not least in those areas where drastic changes are projected.

Management of Inherited Arrhythmia Syndromes: A HiRO Consensus Handbook on Process of Care

Inherited arrhythmia syndromes are rare genetic conditions that predispose seemingly healthy individuals to sudden cardiac arrest and death. The Hearts in Rhythm Organization is a multidisciplinary Canadian network of clinicians, researchers, patients, and families that aims to improve care for patients and families with inherited cardiac conditions, focused on those that confer predisposition to arrhythmia and sudden cardiac arrest and/or death. The field is rapidly evolving as research discoveries increase. A streamlined, practical guide for providers to diagnose and follow pediatric and adult patients with inherited cardiac conditions represents a useful tool to improve health system utilization, clinical management, and research related to these conditions. This review provides consensus care pathways for 7 conditions, including the 4 most common inherited cardiac conditions that confer predisposition to arrhythmia, with scenarios to guide investigation, diagnosis, risk stratification, and management. These conditions include Brugada syndrome, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy and related arrhythmogenic cardiomyopathies, and catecholaminergic polymorphic ventricular tachycardia. In addition, an approach to investigating and managing sudden cardiac arrest, sudden unexpected death, and first-degree family members of affected individuals is provided. Referral to specialized cardiogenetic clinics should be considered in most cases. The intention of this review is to offer a framework for the process of care that is useful for both experts and nonexperts, and related allied disciplines such as hospital management, diagnostic services, coroners, and pathologists, in order to provide high-quality, multidisciplinary, standardized care.

A41 FONTAN ASSOCIATED LIVER DISEASE: THE ROLE OF TRANSIENT ELASTOGRAPHY IN CHILDREN AND ADOLESCENTS

Background

Non-invasive assessment of Fontan Associated Liver Disease (FALD) is of interest, but studies have yielded inconsistent results about the correlation of severity of disease with laboratory values and imaging. Transient elastography (TE) is a non-invasive imaging modality used commonly for liver stiffness measurement (LSM) and in Fontan patients it is hypothesized to reflect not only liver fibrosis but also venous congestion.

Purpose

To better define the potential role of TE for non-invasive assessment of the severity of FALD.

Method

This was a retrospective study conducted on patients’ medical records at CHU Sainte-Justine Hospital. Patients less than 18 years of age with FALD who had at undergone at least one LSM by TE between 1998-2021 were included. The relationship between LSM and liver function tests, hepatic ultrasound findings (including a cirrhosis score), cardiac catheterization results and histological fibrosis scores were analyzed. The impact of interventions during cardiac catherization on LSM were also studied.

Result(s)

A total of 54 patients (36 boys and 18 girls) with FALD were studied. Median age at Fontan surgery was 4.6 years (IQR 4.0 ─ 5.4 years). Higher LSM values significantly correlated with longer time from Fontan, higher total and direct bilirubin and GGT levels, higher INR, longer APTT, lower Factor V, and lower absolute lymphocyte count. Greater LSM was also significantly associated with the presence of heterogenous parenchymal echogenicity, irregular liver contours and greater ultrasonographic cirrhosis scores. Higher TE values were significantly correlated with higher wedged hepatic venous pressure and Fontan pressure. After catherization interventions that addressed stenoses, there was a statistically significant reduction in mean LSM (24.9±3.63 kPa vs 15.8±4.6 kPa, p=0.005). After closure of significant pulmonary collaterals, mean LSM tended to increase, but this difference did not reach statistical significance (19.1±1.9 kPa vs 24.6±3.5 kPa, p=0.2). At liver biopsy, significant direct correlation was found between LSM and the grade of sinusoidal fibrosis and LSM. TE with values >20 kPa were found to have higher grades of sinusoidal fibrosis, while values <20kPa had higher grades of sinusoidal dilatation.

Conclusion(s)

This study showed that TE allows to identify patients with higher cholestatic parameters, more severe liver fibrosis at biopsy and sonographic signs suggestive of cirrhosis. Moreover, it confirmed that liver congestion significantly contributes to LSM values. Interestingly, catheter interventions addressing pulmonary stenoses led to the improvement of TE measurements, giving hope for the reduction of hepatic venous congestion in these patients, which might have an effect on their FALD. Finally, the LSM threshold of 20 kPa could be useful clinically as a value above which fibrosis is likely to be significant, while if below could indicate a greater contribution from hepatic congestion.

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Disclosure of Interest

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Pyrocarbon interposition implant after lunate resection in Kienböck's disease: A case series

In advanced stages of Kienböck's disease, the lunate is no longer conservable. One of the surgical options is to resect the lunate and replace it with a prosthesis. The procedure consisted in lunate resection and interposition of a free APSI® or Pi2® pyrocarbon implant through a dorsal approach. Follow-up was clinical and radiological on QuickDASH and PRWE scores. At a median follow-up of 3 years, 12 patients were reviewed, with a median age of 56 years. Flexion significantly decreased from 42° to 28° (p < 0.01). Extension and pronation-supination were conserved. Strength was 94% compared to the opposite side, with no significant difference from the preoperative measurement. Median QuickDASH and PRWE scores were 15.9 and 23.5 respectively and had significantly improved. One patient underwent scaphocapitate fusion because she was still in pain; the other patients were pain-free. No patients had to change jobs because of their wrist. Radiographically, there was no carpal collapse and carpal height was conserved. Radioscaphoid angle and ulnar translation were stable. There was 1 case of asymptomatic implant dislocation. Interposition of a pyrocarbon implant after lunate resection in advanced Kienböck's disease is a motion-conserving procedure that provides pain relief and functional recovery in the short and medium term. LEVEL OF EVIDENCE: IV.

Clinical management guidelines for Friedreich ataxia: best practice in rare diseases

BACKGROUND

Individuals with Friedreich ataxia (FRDA) can find it difficult to access specialized clinical care. To facilitate best practice in delivering healthcare for FRDA, clinical management guidelines (CMGs) were developed in 2014. However, the lack of high-certainty evidence and the inadequacy of accepted metrics to measure health status continues to present challenges in FRDA and other rare diseases. To overcome these challenges, the Grading of Recommendations Assessment and Evaluation (GRADE) framework for rare diseases developed by the RARE-Bestpractices Working Group was adopted to update the clinical guidelines for FRDA. This approach incorporates additional strategies to the GRADE framework to support the strength of recommendations, such as review of literature in similar conditions, the systematic collection of expert opinion and patient perceptions, and use of natural history data.

METHODS

A panel representing international clinical experts, stakeholders and consumer groups provided oversight to guideline development within the GRADE framework. Invited expert authors generated the Patient, Intervention, Comparison, Outcome (PICO) questions to guide the literature search (2014 to June 2020). Evidence profiles in tandem with feedback from individuals living with FRDA, natural history registry data and expert clinical observations contributed to the final recommendations. Authors also developed best practice statements for clinical care points that were considered self-evident or were not amenable to the GRADE process.

RESULTS

Seventy clinical experts contributed to fifteen topic-specific chapters with clinical recommendations and/or best practice statements. New topics since 2014 include emergency medicine, digital and assistive technologies and a stand-alone section on mental health. Evidence was evaluated according to GRADE criteria and 130 new recommendations and 95 best practice statements were generated.

DISCUSSION AND CONCLUSION

Evidence-based CMGs are required to ensure the best clinical care for people with FRDA. Adopting the GRADE rare-disease framework enabled the development of higher quality CMGs for FRDA and allows individual topics to be updated as new evidence emerges. While the primary goal of these guidelines is better outcomes for people living with FRDA, the process of developing the guidelines may also help inform the development of clinical guidelines in other rare diseases.

Time in Therapeutic Range With Vitamin K Antagonists in Congenital Heart Disease: A Multicentre Study

BACKGROUND

Vitamin K antagonists (VKAs) are frequently prescribed to patients with congenital heart disease (CHD) for atrial arrhythmias or Fontan palliation, but there is a paucity of data regarding time spent in the therapeutic range (TTR). We sought to determine the TTR in patients with CHD and atrial arrhythmias or Fontan palliation prescribed VKAs and explore associations with thromboembolic and bleeding events.

METHODS

A multicentre North American cohort study was conducted on patients with CHD who received VKAs for sustained atrial arrhythmia or Fontan palliation. TTR was calculated using the Rosendaal linear interpolation method. Generalized estimating equations were used to explore factors associated with time outside the therapeutic range.

RESULTS

A total of 567 patients, aged 33 ± 17 years, 56% female, received VKAs for 11.5 ± 8.4 years for atrial arrhythmias (63.0%) or Fontan palliation (58.0%). CHD was simple, moderate, and complex in 10.8%, 20.3%, and 69.0%, respectively. Site investigators perceived good control over international normalized ratio (INR) levels in most patients (75.3%), with no or minor compliance or adherence issues (85.6%). The mean TTR was 41.9% (95% confidence interval [CI], 39.0%-44.8%). Forty-seven (8.3%) and 34 (6.0%) patients had thromboembolic and bleeding events, respectively. Thromboembolic events were associated with a higher proportion of time below the therapeutic range (31.3% vs 19.1%, P = 0.003) and bleeding complications with a higher proportion of time above the therapeutic range (32.5% vs 19.5%, P = 0.006).

CONCLUSIONS

Patients with CHD who receive VKAs spend < 42% of their time with INR levels in the therapeutic range, with repercussions regarding thromboembolic and bleeding complications.

Use of antibiotics in pyogenic flexor tenosynovitis

Pyogenic flexor tenosynovitis is a frequent and serious condition. However, there is no consensus on the use of antibiotics. The objective of our study was to describe the treatment of this condition and to identify the surgical and medical management parameters to propose an effective and consensual postoperative antibiotic therapy protocol. We retrospectively reviewed pyogenic flexor tenosynovitis of the thumb or fingers treated between 01/01/2013 and 01/01/2018 at a teaching hospital. Inclusion criteria were confirmation of the clinical diagnosis intraoperatively and a minimum post-antibiotic follow-up of 6 months. Comorbidities, type of surgery, antibiotic therapy parameters, and treatment outcome were assessed. One hundred and thirteen patients were included. Fifty-four percent had comorbidities. The most frequent germ was staphylococcus, all patients received postoperative antibiotic therapy. Intravenous or intravenous followed by oral administration did not provide any benefit compared to an exclusively oral treatment (p = 0.46). The duration of postoperative antibiotic therapy (less than 7 days, between 7 and 14 days or more than 14 days) did not lead to any difference in healing rate (p = 0.67). However, treating for less than 7 days versus 7-14 days seemed to be associated with a higher risk of failure, although not statistically significant. Oral postoperative antibiotic therapy with amoxicillin + clavulanic acid for 7-14 days appears to be effective, allowing for outpatient management.

Sex Differences and Utility of Treadmill Testing in Long‐QT Syndrome

Background

Diagnosis of congenital long‐QT syndrome (LQTS) is complicated by phenotypic ambiguity, with a frequent normal‐to‐borderline resting QT interval. A 3‐step algorithm based on exercise response of the corrected QT interval (QTc) was previously developed to diagnose patients with LQTS and predict subtype. This study evaluated the 3‐step algorithm in a population that is more representative of the general population with LQTS with milder phenotypes and establishes sex‐specific cutoffs beyond the resting QTc.

Methods and Results

We identified 208 LQTS likely pathogenic or pathogenic KCNQ1 or KCNH2 variant carriers in the Canadian NLQTS (National Long‐QT Syndrome) Registry and 215 unaffected controls from the HiRO (Hearts in Rhythm Organization) Registry. Exercise treadmill tests were analyzed across the 5 stages of the Bruce protocol. The predictive value of exercise ECG characteristics was analyzed using receiver operating characteristic curve analysis to identify optimal cutoff values. A total of 78% of male carriers and 74% of female carriers had a resting QTc value in the normal‐to‐borderline range. The 4‐minute recovery QTc demonstrated the best predictive value for carrier status in both sexes, with better LQTS ascertainment in female patients (area under the curve, 0.90 versus 0.82), with greater sensitivity and specificity. The optimal cutoff value for the 4‐minute recovery period was 440 milliseconds for male patients and 450 milliseconds for female patients. The 1‐minute recovery QTc had the best predictive value in female patients for differentiating LQTS1 versus LQTS2 (area under the curve, 0.82), and the peak exercise QTc had a marginally better predictive value in male patients for subtype with (area under the curve, 0.71). The optimal cutoff value for the 1‐minute recovery period was 435 milliseconds for male patients and 455 milliseconds for femal patients.

Conclusions

The 3‐step QT exercise algorithm is a valid tool for the diagnosis of LQTS in a general population with more frequent ambiguity in phenotype. The algorithm is a simple and reliable method for the identification and prediction of the 2 major genotypes of LQTS.

Medical Management of Infants With Supraventricular Tachycardia: Results From a Registry and Review of the Literature

Background

Several medication choices are available for acute and prophylactic treatment of refractory supraventricular tachycardia (SVT) in infants. There are almost no controlled trials, and medication choices are not necessarily evidence based. Our objective was to report the effectiveness of management strategies for infant SVT.

Methods

A registry of infants admitted to hospital with re-entrant SVT and no haemodynamically significant heart disease were prospectively followed at 11 international tertiary care centres. In addition, a systematic review of studies on infant re-entrant SVT in MEDLINE and EMBASE was conducted. Data on demographics, symptoms, acute and maintenance treatments, and outcomes were collected.

Results

A total of 2534 infants were included: n = 108 from the registry (median age, 9 days [0-324 days], 70.8% male) and n = 2426 from the literature review (median age, 14 days; 62.3% male). Propranolol was the most prevalent acute (61.4%) and maintenance treatment (53.8%) in the Registry, whereas digoxin was used sparingly (4.0% and 3.8%, respectively). Propranolol and digoxin were used frequently in the literature acutely (31% and 33.2%) and for maintenance (17.8% and 10.1%) (P < 0.001). No differences in acute or prophylactic effectiveness between medications were observed. Recurrence was higher in the Registry (25.0%) vs literature (13.4%) (P < 0.001), and 22 (0.9%) deaths were reported in the literature vs none in the Registry.

Conclusion

This was the largest cohort of infants with SVT analysed to date. Digoxin monotherapy use was rare amongst contemporary paediatric cardiologists. There was limited evidence to support one medication over another. Overall, recurrence and mortality rates on antiarrhythmic treatment were low.

OUP accepted manuscript

Aims

Genetic testing is recommended in specific inherited heart diseases but its role remains unclear and it is not currently recommended in unexplained cardiac arrest (UCA). We sought to assess the yield and clinical utility of genetic testing in UCA using whole-exome sequencing (WES).

Methods and results

Survivors of UCA requiring external defibrillation were included from the Cardiac Arrest Survivor with Preserved Ejection fraction Registry. Whole-exome sequencing was performed, followed by assessment of rare variants in previously reported cardiovascular disease genes. A total of 228 UCA survivors (mean age at arrest 39 ± 13 years) were included. The majority were males (66%) and of European ancestry (81%). Following advanced clinical testing at baseline, the likely aetiology of cardiac arrest was determined in 21/228 (9%) cases. Whole-exome sequencing identified a pathogenic or likely pathogenic (P/LP) variant in 23/228 (10%) of UCA survivors overall, increasing the proportion of ‘explained’ cases from 9% only following phenotyping to 18% when combining phenotyping with WES. Notably, 13 (57%) of the 23 P/LP variants identified were located in genes associated with cardiomyopathy, in the absence of a diagnosis of cardiomyopathy at the time of arrest.

Conclusions

Genetic testing identifies a disease-causing variant in 10% of apparent UCA survivors. The majority of disease-causing variants was located in cardiomyopathy-associated genes, highlighting the arrhythmogenic potential of such variants in the absence of an overt cardiomyopathy diagnosis. The present study supports the use of genetic testing including assessment of arrhythmia and cardiomyopathy genes in survivors of UCA.

Return of Results Policies for Genomic Research: Current Practices & The Hearts in Rhythm Organization Approach

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.