Endomyocardial biopsy: safety and prognostic utility in paediatric and adult myocarditis in the European Society of Cardiology EURObservational Research Programme Cardiomyopathy and Myocarditis Long-Term Registry

BACKGROUND AND AIMS

Contemporary multicentre data on clinical and diagnostic spectrum and outcome in myocarditis are limited. Study aims were to describe baseline features, 1-year follow-up, and baseline predictors of outcome in clinically suspected or biopsy-proven myocarditis (2013 European Society of Cardiology criteria) in adult and paediatric patients from the EURObservational Research Programme Cardiomyopathy and Myocarditis Long-Term Registry.

METHODS

Five hundred eighty-one (68.0% male) patients, 493 adults, median age 38 (27-52) years, and 88 children, aged 8 (3-13) years, were divided into 3 groups: Group 1 (n = 233), clinically suspected myocarditis with abnormal cardiac magnetic resonance; Group 2 (n = 222), biopsy-proven myocarditis; and Group 3 (n = 126) clinically suspected myocarditis with normal or inconclusive or no cardiac magnetic resonance. Baseline features were analysed overall, in adults vs. children, and among groups. One-year outcome events included death/heart transplantation, ventricular assist device (VAD) or implantable cardioverter defibrillator (ICD) implantation, and hospitalization for cardiac causes.

RESULTS

Endomyocardial biopsy, mainly right ventricular, had a similarly low complication rate in children and adults (4.7% vs. 4.9%, P = NS), with no procedure-related death. A classical myocarditis pattern on cardiac magnetic resonance was found in 31.3% of children and in 57.9% of adults with biopsy-proven myocarditis (P < .001). At 1-year follow-up, 11/410 patients (2.7%) died, 7 (1.7%) received a heart transplant, 3 underwent VAD (0.7%), and 16 (3.9%) underwent ICD implantation. Independent predictors at diagnosis of death or heart transplantation or hospitalization or VAD implantation or ICD implantation at 1-year follow-up were lower left ventricular ejection fraction and the need for immunosuppressants for new myocarditis diagnosis refractory to non-aetiology-driven therapy.

CONCLUSIONS

Endomyocardial biopsy was safe, and cardiac magnetic resonance using Lake Louise criteria was less sensitive, particularly in children. Virus-negative lymphocytic myocarditis was predominant both in children and adults, and use of immunosuppressive treatments was low. Lower left ventricular ejection fraction and the need for immunosuppressants at diagnosis were independent predictors of unfavourable outcome events at 1 year.

Performance of the PRIMaCY sudden death risk prediction model for childhood hypertrophic cardiomyopathy: implications for implantable cardioverter-defibrillator decision-making

AIMS

The validated HCM Risk-Kids model provides accurate individualized estimates of sudden cardiac death risk in children with hypertrophic cardiomyopathy (HCM). A second validated model, PRIMaCY, also provides individualized estimates of risk, but its performance and clinical impact has not been independently investigated. The aim of this study was to investigate the clinical impact of using the PRIMaCY sudden cardiac death (SCD) risk model in childhood HCM.

METHODS AND RESULTS

The estimated 5-year SCD risk was calculated for children meeting diagnostic criteria for HCM in a large single-centre cohort using PRIMaCY (clinical and genetic) and HCM Risk-Kids model, and model performance was assessed. Three hundred one patients [median age 10 (interquartile range 4-14)] were followed up for an average of 4.9 (±3.8) years, during which 30 (10.0%) reached the SCD or equivalent event endpoint. Harrell's C-statistic for the clinical and genetic models was 0.66 [95% confidence interval (CI) 0.52-0.8] and 0.66 (95% CI 0.54-0.80) with a calibration slope of 0.19 (95% CI 0.04-0.54) and 0.26 (95% CI -0.03-0.62), respectively. The number needed to treat to potentially treat one life-threatening arrhythmia for the PRIMaCY clinical, PRIMaCY genetic, and HCM Risk-Kids models was 13.7, 14.5, and 9.4, respectively.

CONCLUSION

Although PRIMaCY has a similar discriminatory ability to that reported for HCM Risk-Kids, estimated risk estimates did not correlate well with observed risk. A higher proportion of patients met implantable cardioverter-defibrillator thresholds using PRIMaCY model compared with HCM Risk-Kids. This has important clinical implications as these patients will be exposed to a lifetime risk of complications and inappropriate therapies.

Clinical presentation of calmodulin mutations: the International Calmodulinopathy Registry

AIMS

Calmodulinopathy due to mutations in any of the three CALM genes (CALM1-3) causes life-threatening arrhythmia syndromes, especially in young individuals. The International Calmodulinopathy Registry (ICalmR) aims to define and link the increasing complexity of the clinical presentation to the underlying molecular mechanisms.

METHODS AND RESULTS

The ICalmR is an international, collaborative, observational study, assembling and analysing clinical and genetic data on CALM-positive patients. The ICalmR has enrolled 140 subjects (median age 10.8 years [interquartile range 5-19]), 97 index cases and 43 family members. CALM-LQTS and CALM-CPVT are the prevalent phenotypes. Primary neurological manifestations, unrelated to post-anoxic sequelae, manifested in 20 patients. Calmodulinopathy remains associated with a high arrhythmic event rate (symptomatic patients, n = 103, 74%). However, compared with the original 2019 cohort, there was a reduced frequency and severity of all cardiac events (61% vs. 85%; P = .001) and sudden death (9% vs. 27%; P = .008). Data on therapy do not allow definitive recommendations. Cardiac structural abnormalities, either cardiomyopathy or congenital heart defects, are present in 30% of patients, mainly CALM-LQTS, and lethal cases of heart failure have occurred. The number of familial cases and of families with strikingly different phenotypes is increasing.

CONCLUSION

Calmodulinopathy has pleiotropic presentations, from channelopathy to syndromic forms. Clinical severity ranges from the early onset of life-threatening arrhythmias to the absence of symptoms, and the percentage of milder and familial forms is increasing. There are no hard data to guide therapy, and current management includes pharmacological and surgical antiadrenergic interventions with sodium channel blockers often accompanied by an implantable cardioverter-defibrillator.

Proinflammatory and cardiovascular biomarkers are associated with echocardiographic abnormalities in children with HIV taking antiretroviral therapy

OBJECTIVES

Children with perinatally acquired HIV (PHIV) and taking antiretroviral therapy (ART) have a high prevalence of subclinical cardiac disease. We hypothesized that cardiac disease may be a consequence of dysregulated systemic immune activation driven by HIV infection. We examined cardiovascular and proinflammatory biomarkers and their association with echocardiographic abnormalities in children with PHIV.

DESIGN

Cross-sectional analysis of soluble biomarkers from a prospective cohort of children aged 6-16 years with PHIV and age-matched HIV-uninfected comparison group.

METHODS

Cryopreserved plasma samples were used to measure seven soluble biomarkers using multiplex bead assay (Luminex). Multivariable logistic regression assessed how biomarker levels related to cardiac abnormalities.

RESULTS

A total of 406 children participated in this study (195 PHIV and 211 HIV-uninfected). Mean [standard deviation (SD)] ages of PHIV and HIV-uninfected participants were 10.7 (2.6) and 10.8 (2.8) years, respectively. Plasma levels of CRP, TNF-α, ST2, VCAM-1 and GDF-15 were significantly higher in the PHIV group compared with uninfected control ( P  < 0.001). Among children with PHIV, with one-unit representing one SD in biomarker level, a one-unit increase in CRP and GDF-15, was associated with increased odds of having left ventricular (LV) diastolic dysfunction [adjusted odds ratio (aOR), 1.49 (1.02-2.18; P  < 0.040)] and [aOR 1.71 (1.18-2.53; P  = 0.006)], respectively. Each one unit increase in GDF-15 was associated with increased odds of LV hypertrophy [aOR 1.84 (95% CI 1.10-3.10; P  < 0.021)].

CONCLUSION

Children with PHIV had higher levels of proinflammatory and cardiovascular biomarkers compared with HIV-uninfected children. Increased CRP and GDF-15 were associated with cardiac abnormalities in children with PHIV.

Hypertrophic cardiomyopathy and atrial fibrillation: the Cardiomyopathy/Myocarditis registry of the EURObservational Research Programme of the European Society of Cardiology

Background

Current guidelines for AF management underline a complex approach to detecting and treating atrial fibrillation (AF). Hypertrophic cardiomyopathy (HCM) is commonly associated with AF.

Purpose

To assess the clinical characteristic and prognosis in patients with HCM and AF.

Methods and results

Overall, 1739 adult patients with HCM (711/40.9% female; median age at diagnosis: 55.5 years) were enrolled in the EURObservational Research Programme – Cardiomyopathy/Myocarditis Long-Term Registry. Baseline clinical characteristics and adverse cardiovascular endpoints at 1-year follow-up were analysed.

Results

At baseline, AF was found in 478 (27.5%) subjects (paroxysmal: 54.7%, persistent: 17.6%, permanent: 27.7%). Newly diagnosed AF was identified during 1-year follow-up in 48 (2.8%) subjects with HCM.

The presence of AF was associated with higher age (59.6±13.8 vs 50.8±16.1, p&lt;0.001); BMI (27.7±5.1 vs 26.6±4.6 kg/m2, p&lt;0.001); more advanced NYHA class (NYHA I/II and III/IV: 75.1 and 24.9 vs 86.2 and 13.8%, p&lt;0.001); more frequent history of diabetes (14.6 vs 8.4%, p&lt;0.001); arterial hypertension 43.4 vs 34.6%, p&lt;0.001); renal impairment (15.4 vs 6.35%, p&lt;0.001); and history of sustained VT (10.8 vs 6.35%, p&lt;0.001). AF patients were characterized by lower left ventricular ejection fraction (LV EF) (59±12 vs 63±11%, P&lt;0.001), left atrium (LA) dilatation (48.9±9.1 vs 42.4±7.7%, p&lt;0.001), increased pulmonary artery systolic pressure (37.8±13.7 vs 29.6±12.6 mmHg, p&lt;0.001), distribution of LV hypertrophy (p=0.032) and more advanced LV diastolic dysfunction (p&lt;0.001).

On multivariate logistic regression analysis, independent predictors of AF in the HCM population were: age at enrolment (OR 1.068, P&lt;0.001); LVEF (OR 0.978, p&lt;0.001); and LA diameter (OR 1.094, p&lt;0.001).

Oral anticoagulation (OAC) was administered in 69.5% of patients with AF (vitamin K antagonist: 48.5%; direct OAC: 21%). ICD was implanted in 26.8% in AF and 16.9% in non-AF subjects (p&lt;0.001). PVI was performed in 9.9% of AF patients only.

The annual incidence of stroke/TIA was higher in AF than in the non-AF population (2.64 vs 0.85%, p=0.009). There was a trend towards increased death from any cause in the AF population (3.39 vs 1.74%, p=0.05). There were no differences in SCD-risk score between AF and non-AF subjects.

Conclusion

The study reveals a high prevalence of AF in patients with HCM that corresponds with more advanced symptoms, increased prevalence of comorbidities, structural and functional heart remodelling along with inadequate anticoagulation and a significant increase in the risk of stroke. The clinical characteristics of HCM-AF patients indicate that the ESC recommended complex AF approach “CC To ABC” is appropriate in this population.

Funding Acknowledgement

Type of funding sources: None.

External validation of the HCM Risk-Kids model for predicting sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). The newly developed HCM Risk-Kids model provides clinicians with individualized estimates of risk. The aim of this study was to externally validate the model in a large independent, multi-centre patient cohort.

METHODS AND RESULTS

A retrospective, longitudinal cohort of 421 patients diagnosed with HCM aged 1-16 years independent of the HCM Risk-Kids development and internal validation cohort was studied. Data on HCM Risk-Kids predictor variables (unexplained syncope, non-sustained ventricular tachycardia, maximal left ventricular wall thickness, left atrial diameter, and left ventricular outflow tract gradient) were collected from the time of baseline clinical evaluation. The performance of the HCM Risk-Kids model in predicting risk at 5 years was assessed. Twenty-three patients (5.4%) met the SCD end-point within 5 years, with an overall incidence rate of 2.03 per 100 patient-years [95% confidence interval (CI) 1.48-2.78]. Model validation showed a Harrell's C-index of 0.745 (95% CI 0.52-0.97) and Uno's C-index 0.714 (95% 0.58-0.85) with a calibration slope of 1.15 (95% 0.51-1.80). A 5-year predicted risk threshold of ≥6% identified 17 (73.9%) SCD events with a corresponding C-statistic of 0.702 (95% CI 0.60-0.81).

CONCLUSIONS

This study reports the first external validation of the HCM Risk-Kids model in a large and geographically diverse patient population. A 5-year predicted risk of ≥6% identified over 70% of events, confirming that HCM Risk-Kids provides a method for individualized risk predictions and shared decision-making in children with HCM.

Association between common cardiovascular risk factors and clinical phenotype in patients with hypertrophic cardiomyopathy from the European Society of Cardiology (ESC) EurObservational Research Programme (EORP) Cardiomyopathy/Myocarditis registry

AIMS

The interaction between common cardiovascular risk factors (CVRF) and hypertrophic cardiomyopathy (HCM) is poorly studied. We sought to explore the relation between CVRF and the clinical characteristics of patients with HCM enrolled in the EURObservational Research Programme (EORP) Cardiomyopathy registry.

METHODS AND RESULTS

1739 patients with HCM were studied. The relation between hypertension (HT), diabetes (DM), body mass index (BMI), and clinical traits was analysed. Analyses were stratified according to the presence or absence of a pathogenic variant in a sarcomere gene. The prevalence of HT, DM, and obesity (Ob) was 37, 10, and 21%, respectively. HT, DM, and Ob were associated with older age (P<0.001), less family history of HCM (HT and DM P<0.001), higher New York Heart Association (NYHA) class (P<0.001), atrial fibrillation (HT and DM P<0.001; Ob p = 0.03) and LV (left ventricular) diastolic dysfunction (HT and Ob P<0.001; DM P = 0.003). Stroke was more frequent in HT (P<0.001) and mutation-positive patients with DM (P = 0.02). HT and Ob were associated with higher provocable LV outflow tract gradients (HT P<0.001, Ob P = 0.036). LV hypertrophy was more severe in Ob (P = 0.018). HT and Ob were independently associated with NYHA class (OR 1.419, P = 0.017 and OR 1.584, P = 0.004, respectively). Other associations, including a higher proportion of females in HT and of systolic dysfunction in HT and Ob, were observed only in mutation-positive patients.

CONCLUSION

Common CVRF are associated with a more severe HCM phenotype, suggesting a proactive management of CVRF should be promoted. An interaction between genotype and CVRF was observed for some traits.

Clinical characterisation of hypertrophic cardiomyopathy caused by MYH7 gene variants in children

Background

Variants in the cardiac Beta Myosin Heavy chain 7 gene (MYH7) are a common cause of hypertrophic cardiomyopathy (HCM) in adults, but their role in paediatric-onset HCM has not been systematically characterised. This study aims to describe the presentation, clinical characteristics and outcomes of childhood HCM secondary to disease-causing MYH7 variants.

Methods

Retrospective, longitudinal, data from 70 individuals meeting diagnostic criteria for HCM under the age of 18 years with disease-causing MYH7 variants from a single specialist centre (1991–2019) were collected. A Major Adverse Cardiac Event was defined as sudden cardiac death (SCD), heart failure-related death, cardiac transplantation, haemodynamically-compromising sustained ventricular arrhythmia or appropriate implantable cardioverter defibrillator (ICD) therapy.

Results

Median age at diagnosis was 9.2 years (IQR 4.2–13.3 years); 47 patients (67.1%) were less than 12 years and 7 (10.0%) were under the age of 1 at diagnosis. Twenty-two patients (31.4%) were probands. MYH7 variants were missense (n=67) or truncating (n=1). Reason for presentation were: family screening (n=45, 64.3%); cardiac symptoms (n=12, 17.1%); incidental finding (n=11, 15.7%); and out of hospital cardiac arrest (n=2, 2.9%). At baseline, mean maximum left ventricular wall thickness (MLVWT) z-score was 9.6 (±5.8), 11 patients (15.7%) had resting left ventricular outflow tract obstruction (left ventricular outflow tract gradient ≥30mmHg). Baseline phenotype did not significantly differ between probands and non-probands (MLVWT Z score 11.9 (±4.5) vs 8.5 (±6.1), p-value 0.0675). Over a median follow up of 3.6 years (IQR 1.8–7.9 years), 10 patients (14.3%) underwent a left ventricular septal myectomy at a median age 6.4 years (IQR 3.4–12.1 years) and 27 (38.6%) had an implantable cardioverter defibrillator (ICD) for primary (n=24, 34.3%) or secondary (n=3, 4.3%) prevention. Three patients (4.3%) died (SCD, n=1; heart-failure related, n=1; non-cardiac, n=1) and 3 (4.3%) underwent cardiac transplantation. Ten patients (14.3%) experienced a MACE. Patients who experienced a MACE were more likely to be probands [n= 6 (60.0%) vs n=16 (26.7%); p=0.036] but did not differ in terms of baseline phenotype (p=0.134).

Conclusion

MYH7 variants can cause infantile and childhood-onset disease, which is associated with significant early cardiac morbidity and mortality. Adverse outcomes were more common in those presenting as probands.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Medical Research Council, Great Ormond Street Hospital charity.

Clinical features and natural history of RASopathy-associated hypertrophic cardiomyopathy in children

Background

The RASopathies are a group of genetic disorders caused by germline mutations in genes encoding components of the RAS/MAPK signalling pathway and frequently associated with hypertrophic cardiomyopathy (HCM). The clinical features and outcomes of RASopathy-related HCM are incompletely understood and most published studies are limited by relatively small numbers and incomplete clinical characterisation.

Purpose

To describe the clinical features outcomes in a large, single-centre cohort of patients with RASopathy-associated HCM diagnosed &lt;18 years.

Methods

Data from 105 patients [68 (64.8%) males] diagnosed in childhood with RASopathy-associated HCM at a single specialist centre between 1985 and 2020 were retrospectively analysed.

Results

The RASopathy diagnosis was Noonan syndrome in 69 patients (65.7%); NSML in 10 (9.5%); CFC in 6 (5.7%); Costello in 5 (4.8%) and 15 patients (14.2%) had another Noonan-like variant. 72 patients (68.6%) had a pathogenic/likely pathogenic variant in a RAS-MAPK gene, most commonly PTPN11 [n=25 (34.7%)], followed by RAF 1 [n=13 (18.1%)]. 100 patients (95.2%) were probands, 9 (8.6%) had family history of cardiomyopathy and 2 (1.9%) family history of sudden cardiac death (SCD). 52 (49.5%) had concomitant congenital heart defects (CHD) [ASD 13 (25%), VSD 6 (11.5%), PDA 1 (1.9%), &gt;1 CHD 32 (61.5%)]. 29 (27.6%) had symptoms at baseline assessment and 56 (53.3%) were on cardiac medication. The distribution of left ventricular hypertrophy (LVH) was concentric in 47 (44.7%); 32 (30.5%) had asymmetric septal hypertrophy (ASH), and undocumented in 25 patients (23.8%). 45 patients (42.9%) had biventricular hypertrophy (BVH). Resting left ventricular outflow tract obstruction (LVOTO) was present in 39 (37.1%) with haemodynamically significant LVOTO (≥50mmHg) in 23 (21.9%). Resting right ventricular outflow tract obstruction (RVOTO) was present in 21 (20%). Over a median follow up time of 6 years, 19 patients (18.1%) died [1 (5.3%) SCD; 2 (10.5%) due to Heart Failure-related death; 1 (5.3%) due to another CVS cause; 5 (26.3%) due to a non-CVS cause and for 10 (52.6%) cause of death was unknown]. Incidence rate of death was calculated at 2.7 deaths per 100 person-years. Surgical septal myectomy was performed in 9 patients (8.6%) and 3 (2.9%) underwent cardiac transplantation. 14 patients (13.3%) suffered arrhythmic events [atrial tachycardia 6 (42.9%), Non-Sustained Ventricular Tachycardia 4 (3.8%), and Ventricular Tachycardia/Ventricular Fibrillation 4 (3.8%)].

Conclusion

To our knowledge, this is the largest cohort of RASopathy-associated HCM. The findings show a heterogeneous clinical presentation with a high prevalence of morbidity and mortality. Further work is needed to determine predictors of outcome in this population.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Onassis Foundation

Clinical characteristics and natural history of pre-adolescent non-syndromic hypertrophic cardiomyopathy

Background

The clinical presentation and natural history of pre-adolescent sarcomeric hypertrophic cardiomyopathy (HCM) has not been systematically characterised. The aim of this study was to describe the clinical characteristics and outcomes of a large, international, multicentre cohort of children diagnosed with non-syndromic HCM below the age of 12.

Methods

Data from the International Paediatric Hypertrophic Cardiomyopathy Consortium on 639 children meeting diagnostic criteria for HCM below 12 years of age (pre-adolescent) were collected and compared with 568 diagnosed aged 12–16 years. Patients with syndromic and metabolic HCM were excluded.

Results

Of 639 (male n=417, 65.3%) children with pre-adolescent HCM, 339 (53.1%) had a family history of HCM and 57 (8.9%) a family history of sudden cardiac death (SCD). At the time of baseline assessment; 132 (20.7%) had heart failure symptoms and 39 (6.1%) reported unexplained syncope. Median maximal left ventricular wall thickness on echocardiogram was 13.6mm (IQR 10–19) with a corresponding median z-score of 8.7 (5.3–14.4). 145 (22.7%) had left ventricular outflow tract obstruction (LVOTO) (maximal LVOT gradient≥30mmHg) and 35 (5.5%) had severe LVOTO (gradient≥90mmHg). Over a median follow up 5.6 years (IQR 2.3–10), 10.5% underwent a myectomy and 23.2% implantable cardiac defibrillator (ICD) implantation for primary (81.8%) or secondary (14.2%) prevention. 42 (6.7%) patients died [SCD 4.9%, heart failure death 0.8%, other 1%] and 21 (3.3%) underwent cardiac transplantation. 69 (10.8%) patients had an arrhythmic event (SCD n=31, resuscitated cardiac arrest n=17, appropriate ICD therapy n=14, sustained VT with haemodynamic compromise n=7). Compared to those presenting after 12 years, those under 12 were less likely to have a family history of SCD (8.9% vs 13%, p:0.047) or report unexplained syncope (6.1% vs 12.3%, p&lt;0.00). The degree of hypertrophy did not differ but a higher proportion of pre-adolescent patients had LVOTO (22.7% vs 14.4%, p&lt;0.00). A higher proportion of pre-adolescent underwent a myectomy (10.5% vs 7.2%, p:0.045) but a lower proportion received a primary prevention ICD (18.9% vs 30.1%, p:0.041). The overall proportion of patients reaching the mortality or arrhythmic end-points did not differ, but SCD and resuscitated cardiac arrest events were more frequent in pre-adolescent patients (4.9% vs 3.9% and 2.7 vs 1.6% respectively).

Conclusion

Pre-adolescent HCM is associated with a high symptom burden and variable cardiac phenotype, comparable to those presenting later in childhood. Despite baseline similarities and equal overall survival, younger patients were less likely to receive a primary prevention ICD despite being more likely to experience a SCD or resuscitated cardiac arrest. This study suggests that younger patients should not be considered a distinct entity for risk stratification and that similar management strategies to older HCM patients should be employed.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): BHF (British Heart Foudnation) MRC (Medical Research Council)

External validation of the HCM Risk-Kids model for predicting sudden cardiac death in childhood hypertrophic cardiomyopathy

Background

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). The newly developed HCM Risk-Kids model provides clinicians with individualised estimates of risk. The aim of this study was to externally validate the model in a large independent, multi-centre patient cohort.

Methods

A retrospective, longitudinal cohort of patients diagnosed with HCM aged 1–16 years independent of the HCM-Risk-Kids development and internal validation cohort was studied. Data on HCM Risk-Kids predictor variables (unexplained syncope, non-sustained ventricular tachycardia, maximal left ventricular wall-thickness, left atrial diameter and left ventricular outflow tract gradient) were collected from the time of baseline clinical evaluation. The performance of the HCM Risk-Kids model in predicting risk at 5 years was assessed.

Results

The cohort consisted of 421 patients with a median age at baseline evaluation of 12.3 years (IQR 7.3, 14.4). Over a median total follow up 3.48 years (IQR 1.83, 6.62, range 1 month – 20.7 years). Fourteen patients (3.3%) died and 10 (2.4%) underwent cardiac transplantation. Twenty-three patients (5.4%) met the SCD end-point within 5-years, with an overall incidence rate of 2.03 per 100 patient years (95% CI 1.48–2.78). Model validation showed a Harrell's C-index of 0.745 (95% CI 0.52–0.97) and Uno's C-index 0.714 (95% 0.58–0.85) with a calibration slope of 1.15 (95% 0.51–1.80). Figure 1a describes the agreement between predicted and observed 5-year cumulative proportion of SCD or equivalent events for each tertile of predicted risk in one imputed data set. One hundred and twenty-five (29.7%) patients had a predicted 5-year risk of ≥6%. SCD events occurred in 6 patients (2.0%) with a predicted risk &lt;6% and 17 (13.6%) with a predicted risk ≥6. A 5-year predicted risk threshold of ≥6% identified 17 (73.9%) SCD-events with a corresponding C-statistic of 0.702 (95% CI 0.60–0.81) (Figure 1b).

Conclusions

This study reports the first external validation of the HCM Risk-Kids model in a large and geographically diverse patient population. A 5-year predicted risk of ≥6% identified over 70% of events, confirming that HCM Risk-Kids provides a method for individualised risk predictions and shared decision making in children with HCM. Incorporation of the model into routine clinical care will enable independent prospective model validation and assessment of the effect of its use in clinical practice.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): British Heart FoundationMedical Research Council Observed vs predicted risk by tertilesObserved vs predicted by threshold

Atypical cardiac defects in patients with RASopathies: Updated data on CARNET study

BACKGROUND

RASopathies are a set of relatively common autosomal dominant clinically and genetically heterogeneous disorders. Cardiac outcomes in terms of mortality and morbidity for common heart defects (such as pulmonary valve stenosis and hypertrophic cardiomyopathy) have been reported. Nevertheless, also Atypical Cardiac Defects (ACDs) are described. The aim of the present study was to report both prevalence and cardiac outcome of ACDs in patients with RASopathies.

METHODS

A retrospective, multicentric observational study (CArdiac Rasopathy NETwork-CARNET study) was carried out. Clinical, surgical, and genetic data of the patients who were followed until December 2019 were collected.

RESULTS

Forty-five patients out of 440 followed in CARNET centers had ACDs. Noonan Syndrome (NS), NS Multiple Lentigines (NSML) and CardioFacioCutaneous Syndrome (CFCS) were present in 36, 5 and 4 patients, respectively. Median age at last follow-up was 20.1 years (range 6.9-47 years). Different ACDs were reported, including mitral and aortic valve dysfunction, ascending and descending aortic arch anomalies, coronary arteries dilation, enlargement of left atrial appendage and isolated pulmonary branches diseases. Five patients (11%) underwent cardiac surgery and one of them underwent a second intervention for mitral valve replacement and severe pericardial effusion. No patients died in our cohort until December 2019.

CONCLUSIONS

Patients with RASopathies present a distinct CHD spectrum. Present data suggest that also ACDs must be carefully investigated for their possible impact on the clinical outcome. A careful longitudinal follow up until the individuals reach an adult age is recommended.

The role of the electrocardiographic phenotype in risk stratification for sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

The 12-lead electrocardiogram (ECG) is routinely performed in children with hypertrophic cardiomyopathy (HCM). An ECG risk score has been suggested as a useful tool for risk stratification, but this has not been independently validated. This aim of this study was to describe the ECG phenotype of childhood HCM in a large, international, multi-centre cohort and investigate its role in risk prediction for arrhythmic events.

METHODS AND RESULTS

Data from 356 childhood HCM patients with a mean age of 10.1 years (±4.5) were collected from a retrospective, multi-centre international cohort. Three hundred and forty-seven (97.5%) patients had ECG abnormalities at baseline, most commonly repolarization abnormalities (n = 277, 77.8%); left ventricular hypertrophy (n = 240, 67.7%); abnormal QRS axis (n = 126, 35.4%); or QT prolongation (n = 131, 36.8%). Over a median follow-up of 3.9 years (interquartile range 2.0-7.7), 25 (7%) had an arrhythmic event, with an overall annual event rate of 1.38 (95% CI 0.93-2.04). No ECG variables were associated with 5-year arrhythmic event on univariable or multivariable analysis. The ECG risk score threshold of >5 had modest discriminatory ability [C-index 0.60 (95% CI 0.484-0.715)], with corresponding negative and positive predictive values of 96.7% and 6.7.

CONCLUSION

In a large, international, multi-centre cohort of childhood HCM, ECG abnormalities were common and varied. No ECG characteristic, either in isolation or combined in the previously described ECG risk score, was associated with 5-year sudden cardiac death risk. This suggests that the role of baseline ECG phenotype in improving risk stratification in childhood HCM is limited.

Prospective follow-up in various subtypes of cardiomyopathies: insights from the ESC EORP Cardiomyopathy Registry

AIMS

The European Society of Cardiology (ESC) European Observational Research Programme (EORP) Cardiomyopathy Registry is a prospective multinational registry of consecutive patients with cardiomyopathies. The objective of this report is to describe the short-term outcomes of adult patients (≥18 years old).

METHODS AND RESULTS

Out of 3208 patients recruited, follow-up data at 1 year were obtained in 2713 patients (84.6%) [1420 with hypertrophic (HCM); 1105 dilated (DCM); 128 arrhythmogenic right ventricular (ARVC); and 60 restrictive (RCM) cardiomyopathies]. Improvement of symptoms (dyspnoea, chest pain, and palpitations) was globally observed over time (P < 0.05 for each). Additional invasive procedures were performed: prophylactic implantation of implantable cardioverter-defibrillator (ICD) (5.2%), pacemaker (1.2%), heart transplant (1.1%), ablation for atrial or ventricular arrhythmia (0.5% and 0.1%). Patients with atrial fibrillation increased from 28.7% to 32.2% of the cohort. Ventricular arrhythmias (VF/ventricular tachycardias) in ICD carriers (primary prevention) at 1 year were more frequent in ARVC, then in DCM, HCM, and RCM (10.3%, 8.2%, 7.5%, and 0%, respectively). Major cardiovascular events (MACE) occurred in 29.3% of RCM, 10.5% of DCM, 5.3% of HCM, and 3.9% of ARVC (P < 0.001). MACE were more frequent in index patients compared to relatives (10.8% vs. 4.4%, P < 0.001), more frequent in East Europe centres (13.1%) and least common in South Europe (5.3%) (P < 0.001). Subtype of cardiomyopathy, geographical region, and proband were predictors of MACE on multivariable analysis.

CONCLUSIONS

Despite symptomatic improvement, patients with cardiomyopathies remain prone to major clinical events in the short term. Outcomes were different not only according to cardiomyopathy subtypes but also in relatives vs. index patients, and according to European regions.

Childhood Hypertrophic Cardiomyopathy: A Disease of the Cardiac Sarcomere

Hypertrophic cardiomyopathy is the second most common cause of cardiomyopathy presenting during childhood and whilst its underlying aetiology is variable, the majority of disease is caused by sarcomeric protein gene variants. Sarcomeric disease can present at any age with highly variable disease phenotype, progression and outcomes. The majority have good childhood-outcomes with reported 5-year survival rates above 80%. However, childhood onset disease is associated with considerable life-long morbidity and mortality, including a higher SCD rate during childhood than seen in adults. Management is currently focused on relieving symptoms and preventing disease-related complications, but the possibility of future disease-modifying therapies offers an exciting opportunity to modulate disease expression and outcomes in these young patients.

Calmodulin mutations and life-threatening cardiac arrhythmias: insights from the International Calmodulinopathy Registry

AIMS

Calmodulinopathies are rare life-threatening arrhythmia syndromes which affect mostly young individuals and are, caused by mutations in any of the three genes (CALM 1-3) that encode identical calmodulin proteins. We established the International Calmodulinopathy Registry (ICalmR) to understand the natural history, clinical features, and response to therapy of patients with a CALM-mediated arrhythmia syndrome.

METHODS AND RESULTS

A dedicated Case Report File was created to collect demographic, clinical, and genetic information. ICalmR has enrolled 74 subjects, with a variant in the CALM1 (n = 36), CALM2 (n = 23), or CALM3 (n = 15) genes. Sixty-four (86.5%) were symptomatic and the 10-year cumulative mortality was 27%. The two prevalent phenotypes are long QT syndrome (LQTS; CALM-LQTS, n = 36, 49%) and catecholaminergic polymorphic ventricular tachycardia (CPVT; CALM-CPVT, n = 21, 28%). CALM-LQTS patients have extremely prolonged QTc intervals (594 ± 73 ms), high prevalence (78%) of life-threatening arrhythmias with median age at onset of 1.5 years [interquartile range (IQR) 0.1-5.5 years] and poor response to therapies. Most electrocardiograms (ECGs) show late onset peaked T waves. All CALM-CPVT patients were symptomatic with median age of onset of 6.0 years (IQR 3.0-8.5 years). Basal ECG frequently shows prominent U waves. Other CALM-related phenotypes are idiopathic ventricular fibrillation (IVF, n = 7), sudden unexplained death (SUD, n = 4), overlapping features of CPVT/LQTS (n = 3), and predominant neurological phenotype (n = 1). Cardiac structural abnormalities and neurological features were present in 18 and 13 patients, respectively.

CONCLUSION

Calmodulinopathies are largely characterized by adrenergically-induced life-threatening arrhythmias. Available therapies are disquietingly insufficient, especially in CALM-LQTS. Combination therapy with drugs, sympathectomy, and devices should be considered.

Cardiac phenotype in ATP1A3-related syndromes: A multicenter cohort study

OBJECTIVE

To define the risks and consequences of cardiac abnormalities in ATP1A3-related syndromes.

METHODS

Patients meeting clinical diagnostic criteria for rapid-onset dystonia-parkinsonism (RDP), alternating hemiplegia of childhood (AHC), and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS) with ATP1A3 genetic analysis and at least 1 cardiac assessment were included. We evaluated the cardiac phenotype in an Atp1a3 knock-in mouse (Mashl^+/-) to determine the sequence of events in seizure-related cardiac death.

RESULTS

Ninety-eight patients with AHC, 9 with RDP, and 3 with CAPOS (63 female, mean age 17 years) were included. Resting ECG abnormalities were found in 52 of 87 (60%) with AHC, 2 of 3 (67%) with CAPOS, and 6 of 9 (67%) with RDP. Serial ECGs showed dynamic changes in 10 of 18 patients with AHC. The first Holter ECG was abnormal in 24 of 65 (37%) cases with AHC and RDP with either repolarization or conduction abnormalities. Echocardiography was normal. Cardiac intervention was required in 3 of 98 (≈3%) patients with AHC. In the mouse model, resting ECGs showed intracardiac conduction delay; during induced seizures, heart block or complete sinus arrest led to death.

CONCLUSIONS

We found increased prevalence of ECG dynamic abnormalities in all ATP1A3-related syndromes, with a risk of life-threatening cardiac rhythm abnormalities equivalent to that in established cardiac channelopathies (≈3%). Sudden cardiac death due to conduction abnormality emerged as a seizure-related outcome in murine Atp1a3-related disease. ATP1A3-related syndromes are cardiac diseases and neurologic diseases. We provide guidance to identify patients potentially at higher risk of sudden cardiac death who may benefit from insertion of a pacemaker or implantable cardioverter-defibrillator.

227A novel risk prediction model for sudden cardiac death in childhood hypertrophic cardiomyopathy (HCM Risk-Kids)

Background

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM) but there is no validated algorithm to identify those at highest risk. This study sought to develop and validate a SCD risk prediction model that provides individualized risk estimates.

Methods

A prognostic model was derived from an international, retrospective, multi-center longitudinal cohort study of 1024 consecutively evaluated patients aged ≤16 years. The model was developed using pre-selected predictor variables [unexplained syncope, maximal left ventricular (LV) wall thickness (MWT), left atrial diameter (LAD), LV outflow tract (LVOT) gradient and non-sustained ventricular tachycardia (NSVT)] identified from the literature and internally validated using bootstrapping.

Results

Over a median follow up of 5.3 years (IQR 2.6, 8.2, total patient years 5984), 89 (8.7%) patients died suddenly or had an equivalent event [annual event rate 1.49 (95% CI 1.15–1.92)]. The pediatric model was developed using pre-selected variables to predict the risk of SCD. The model's ability to predict risk at 5 years was validated; C-statistic was 0.69 (95% CI 0.66–0.72) and the calibration slope was 0.98 (95% CI 0.58–1.38). For every 10 ICDs implanted in patients with ≥6% 5-year SCD risk, potentially 1 patient will be saved from SCD at 5 years.

Conclusions

This new validated risk stratification model for SCD in childhood HCM provides accurate individualized estimates of risk at 5 years using readily obtained clinical risk factors.

Acknowledgement/Funding

British Heart Foundation

P334Prospective FU in various subtypes of cardiomyopathies: insights from the EORP Cardiomyopathy Registry of the ESC

Background

The EORP Cardiomyopathy Registry is a prospective, observational, multinational registry of consecutive patients with cardiomyopathies. The objective of this report is to describe the outcomes at one year of follow-up of adult patients (>18 years old) enrolled in the registry.

Methods

A total of 3,208 patients (median age: 55.0 (43.0; 64.0) years, males: 65.1%) were recruited at baseline. Follow-up data at 1 year were obtained in 2,713 patients (84.6%), including 1,420 with hypertrophic (HCM), 1,105 dilated (DCM), 128 arrhythmogenic right ventricular (ARVC) and 60 restrictive cardiomyopathy (RCM).

Results

Improvement of symptoms (NYHA, chest pain, syncope) was globally observed over time (p<0.001 for each). Additional invasive therapeutics were performed during follow-up: implantation of ICD (primary prevention) (N=109 patients, 5.2%), pacemaker (N=28, 1.2%), heart transplant (N=30, 1,1%), ablation for atrial or ventricular arrhythmia (0.5% & 0.1%). The proportion of patients with history of AF increased from baseline to FU in 3.6% (from 28.2% to 31.8%). ICD therapy at 1 year was delivered more frequently in ARVC then in DCM, HCM and RCM (11.4%, 9.0%; 8.1%, 0% respectively for primary prevention). Major cardiovascular events (MACE) occurred in 29.3% of RCM, 10.5% of DCM, 7.9% of ARVC and 5.3% of HCM. MACE were globally higher in index patients compared to relatives (10.8% vs 4.4%, p<0.001).

When considering geographical areas, MACE were higher in East Europe (13.1%) and lower in South Europe (5.3%) (univariate); heart transplant was higher in West Europe (2.40%) and lower in South Europe (0.25%) (univariate).

Conclusions

Despite symptomatic improvement in most cases, there is still a significant burden of arrhythmic and heart failure events in patients with cardiomyopathies. Outcomes were different not only according to cardiomyopathy subtypes but also in relatives versus index patients.

Acknowledgement/Funding

None

P3443Myotonic dystrophy type 1 in childhood: benign from a cardiac perspective?

Introduction/Purpose

Patients with myotonic dystrophy (DM1) have an increased risk of cardiac conduction disease and ventricular tachycardia associated with sudden cardiac death. Whilst this is well-established in adults, there is little published data on cardiac abnormalities in paediatric patients. To our knowledge this is the largest described cohort of children with DM1. The aim of this study is to better understand the prevalence and type of cardiac abnormalities in paediatric patients with DM1.

Methods

We retrospectively studied consecutive patients referred to our paediatric quaternary institution between 31 December 2000 and 31 January 2019. The electronic patient record was reviewed for the presence of cardiac manifestations, including clinical assessment in clinic, echocardiogram, 12 lead ECG and 24-hour ECG.

Results

60 children were identified with a diagnosis of DM1, 56 (93%) with the congenital form of the disease. The median age at diagnosis was 2.4 (IQR 1.2–24, n=52) months. 51 (85%) were under regular formal cardiac follow up. Cardiac symptoms (syncope, palpitations or chest pain) were present in 6 (10%). 12 lead ECGs were available in 50 (83%) and there was at least one echocardiogram performed in 57 (95%). There were 3 deaths (5%), 2 sudden and unexplained (aged 11 and 6.5 years old). 1 child (2%) underwent pacemaker implantation due to the presence of syncope and evidence of progressive conduction disease (Mobitz II AV block).

During the period of follow-up, 37 (62%) patients had evidence of conduction disease on 12 lead ECG or Holter: 1st degree or higher AV block (35%, n=21), trifascicular block (6.7%, n=4), intraventricular conduction delay (32%, n=19), prolonged QTc (15%, n=9) and junctional rhythm (5% n=3). In addition to abnormalities of conduction, 27 (45%) patients had axis deviation and 12 (20%) abnormal repolarisation.

Abnormalities were present in 8 (14%) of those with an echocardiogram. 2 (3.5%) had hypertrophic cardiomyopathy. Other abnormalities included bicuspid aortic valve, aortic root dilatation, dyskinetic septal motion, pericardial effusion, mitral valve thickening and perimembranous VSD.

24 (40%) patients had a signal averaged ECG of which 14 (58%) were positive in 1 or more vector. 3 (5%) patients had an exercise test with no arrhythmia or progression of conduction abnormalities. 1 patient had an invasive EP study showing a prolonged HV interval but no inducible ventricular tachycardia.

Conclusions

There appears to be a high incidence of cardiac involvement in children with DM1. Adverse events (death and pacemaker implantation) are represented in our cohort. More studies are required in order to establish how we might better identify those at risk of progression of conduction disease and ventricular arrhythmia. Regular and lifelong cardiac follow up is advisable but risk stratification and device implantation remains challenging.

Development of a Novel Risk Prediction Model for Sudden Cardiac Death in Childhood Hypertrophic Cardiomyopathy (HCM Risk-Kids)

Importance

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM), but there is no validated algorithm to identify those at highest risk.

Objective

To develop and validate an SCD risk prediction model that provides individualized risk estimates.

Design, Setting, and Participants

A prognostic model was developed from a retrospective, multicenter, longitudinal cohort study of 1024 consecutively evaluated patients aged 16 years or younger with HCM. The study was conducted from January 1, 1970, to December 31, 2017.

Exposures

The model was developed using preselected predictor variables (unexplained syncope, maximal left-ventricular wall thickness, left atrial diameter, left-ventricular outflow tract gradient, and nonsustained ventricular tachycardia) identified from the literature and internally validated using bootstrapping.

Main Outcomes and Measures

A composite outcome of SCD or an equivalent event (aborted cardiac arrest, appropriate implantable cardioverter defibrillator therapy, or sustained ventricular tachycardia associated with hemodynamic compromise).

Results

Of the 1024 patients included in the study, 699 were boys (68.3%); mean (interquartile range [IQR]) age was 11 (7-14) years. Over a median follow-up of 5.3 years (IQR, 2.6-8.3; total patient years, 5984), 89 patients (8.7%) died suddenly or had an equivalent event (annual event rate, 1.49; 95% CI, 1.15-1.92). The pediatric model was developed using preselected variables to predict the risk of SCD. The model's ability to predict risk at 5 years was validated; the C statistic was 0.69 (95% CI, 0.66-0.72), and the calibration slope was 0.98 (95% CI, 0.59-1.38). For every 10 implantable cardioverter defibrillators implanted in patients with 6% or more of a 5-year SCD risk, 1 patient may potentially be saved from SCD at 5 years.

Conclusions and Relevance

This new, validated risk stratification model for SCD in childhood HCM may provide individualized estimates of risk at 5 years using readily obtained clinical risk factors. External validation studies are required to demonstrate the accuracy of this model's predictions in diverse patient populations.

Data on cardiac defects, morbidity and mortality in patients affected by RASopathies. CARNET study results

A comprehensive description of morbidity and mortality in patients affected by mutations in genes encoding for signal transducers of the RAS-MAPK cascade (RASopathies) was performed in our study recently published in the International Journal of Cardiology. Seven European cardiac centres participating to the CArdiac Rasopathy NETwork (CARNET), collaborated in this multicentric, observational, retrospective data analysis and collection. In this study, clinical records of 371 patients with confirmed molecular diagnosis of RASopathy were reviewed. Cardiac defects, crude mortality, survival rate of patients with 1) hypertrophic cardiomyopathy (HCM) and age <2 years or young adults; 2) individuals with Noonan syndrome and pulmonary stenosis carrying PTPN11 mutations; 3) biventricular obstruction and PTPN11 mutations; 4) Costello syndrome or cardiofaciocutaneous syndrome were analysed. Mortality was described as crude mortality, cumulative survival and restricted estimated mean survival. In particular, with this Data In Brief (DIB) paper, the authors aim to report specific statistic highlights of the multivariable regression analysis that was used to assess the impact of mutated genes on number of interventions and overall prognosis.

Cardiac defects, morbidity and mortality in patients affected by RASopathies. CARNET study results

BACKGROUND

RASopathies are developmental disease caused by mutations in genes encoding for signal transducers of the RAS-MAPK cascade. The aim of the present study was to provide a comprehensive description of morbidity and mortality in patients with molecularly confirmed RASopathy.

METHODS

A multicentric, observational, retrospective study was conducted in seven European cardiac centres participating to the CArdiac Rasopathy NETwork (CARNET). Clinical records of 371 patients with confirmed molecular diagnosis of RASopathy were reviewed. Mortality was described as crude mortality, cumulative survival and restricted estimated mean survival. Multivariable regression analysis was used to assess the impact of mutated genes on number of interventions and overall prognosis.

RESULTS

Cardiac defects occurred in 80.3% of cases, almost half of them underwent at least one intervention. Overall, crude mortality was 0.29/100 patients-year. Cumulative survival was 98.8%, 98.2%, 97.7%, 94.3%, at 1, 5, 10, and 20years, respectively. Restricted estimated mean survival at 20years follow-up was 19.6years. Ten patients died (2.7% of the entire cohort; 3.4% of patients with cardiac defect). Patients with hypertrophic cardiomyopathy (HCM) and age <2years or young adults, as well as subjects with biventricular obstruction and PTPN11 mutations had a higher risk of cardiac death.

CONCLUSIONS

The risk of intervention was higher in individuals with Noonan syndrome and pulmonary stenosis carrying PTPN11 mutations. Overall, mortality was relatively low, even though the specific association between HCM, biventricular outflow tract obstructions and PTPN11 mutations appeared to be associated with early mortality, including immediate post-operative events and sudden death.

Echocardiographic reference ranges in older children and adolescents in sub-Saharan Africa

Background

Echocardiographic reference ranges are important to identify abnormalities of cardiac dimensions. Reference ranges for children in sub-Saharan Africa have not been established. The aim of this study was to establish echocardiographic z-score references for Black children in sub-Saharan Africa.

Methods

282 healthy subjects aged 6–16 years (143 [51%] males) with no known history of cardiac disease were enrolled in the study in Harare, Zimbabwe between 2014 and 2016. Standard M-mode echocardiography was performed and nine cardiac chamber dimensions were obtained. Two non-linear statistical models (gamma weighted model and cubic polynomial model) were tested on the data and the best fitting model was used to calculate z-scores of these cardiac chamber measures. The reference ranges are presented on scatter plots against BSA.

Results

Normative data for the following cardiac measures were obtained and z-scores calculated: right ventricular diameter at end diastole (RVEDD); left ventricular diameter at end diastole (LVEDD) and systole (LVESD); interventricular septal wall thickness at end diastole (IVSd) and systole (IVSs); left ventricular posterior wall thickness at end diastole (LVPWd) and systole (LVPWs); left atrium diameter at end systole (LA) and tricuspid annular plane systolic excursion (TAPSE). Girls had higher values for BMI and heart rate than boys (p = 0.048 and p = 0.001, respectively). Mean interventricular septal and left ventricular posterior walls thickness was higher than published normal values in predominantly Caucasian populations.

Conclusion

These are the first echocardiographic reference ranges for children from sub Saharan Africa and will allow accurate assessment of cardiac dimensions in clinical practice.

ECG ABNORMALITIES IN ALTERNATING HEMIPLEGIA: A BROADENED PHENOTYPE

Introduction

Alternating hemiplegia of Childhood (AH) caused by de novo mutations in ATP1A3, is characterised by recurrent plegic and dystonic episodes, seizures, non-paroxysmal neurological features, and dysautonomia. Premature mortality is observed and attributed to sudden unexpected death in epilepsy. A single case of asystole in AH is reported. Other neuronal channelopathies have cardiac involvement, and since ATP1A3 is expressed in cardiomyocytes, we hypothesised that ECG abnormalities are present in AH.

Methods

52 patients fulfilling the diagnostic criteria for AH were recruited, and screened for ATP1A3 mutations. ECGs were analysed for heart rate, cardiac axis, PR, QRS, RR, and QTc intervals, repolarisation patterns, and J-point abnormalities.

Results

53.8% exhibited abnormal resting 12-lead ECGs independent of seizures or AH episodes; 48.1% had repolarisation abnormalities. The proportion of intraventricular conduction delay or partial right bundle branch block was greater in this cohort compared to the general population. ECG abnormalities were significantly greater in patients >16 years than in those <16 years (p=0.0095), and also within the most common mutation group (D801N; p=0.045).

Conclusions

These ECG abnormalities reflect impaired repolarisation reserve in AH in an age-dependent manner, and may account for some cases of premature mortality observed. Long-term cardiac surveillance in AH is recommended.

Faulty cardiac repolarization reserve in alternating hemiplegia of childhood broadens the phenotype

Alternating hemiplegia of childhood is a rare disorder caused by de novo mutations in the ATP1A3 gene, expressed in neurons and cardiomyocytes. As affected individuals may survive into adulthood, we use the term 'alternating hemiplegia'. The disorder is characterized by early-onset, recurrent, often alternating, hemiplegic episodes; seizures and non-paroxysmal neurological features also occur. Dysautonomia may occur during hemiplegia or in isolation. Premature mortality can occur in this patient group and is not fully explained. Preventable cardiorespiratory arrest from underlying cardiac dysrhythmia may be a cause. We analysed ECG recordings of 52 patients with alternating hemiplegia from nine countries: all had whole-exome, whole-genome, or direct Sanger sequencing of ATP1A3. Data on autonomic dysfunction, cardiac symptoms, medication, and family history of cardiac disease or sudden death were collected. All had 12-lead electrocardiogram recordings available for cardiac axis, cardiac interval, repolarization pattern, and J-point analysis. Where available, historical and prolonged single-lead electrocardiogram recordings during electrocardiogram-videotelemetry were analysed. Half the cohort (26/52) had resting 12-lead electrocardiogram abnormalities: 25/26 had repolarization (T wave) abnormalities. These abnormalities were significantly more common in people with alternating hemiplegia than in an age-matched disease control group of 52 people with epilepsy. The average corrected QT interval was significantly shorter in people with alternating hemiplegia than in the disease control group. J wave or J-point changes were seen in six people with alternating hemiplegia. Over half the affected cohort (28/52) had intraventricular conduction delay, or incomplete right bundle branch block, a much higher proportion than in the normal population or disease control cohort (P = 0.0164). Abnormalities in alternating hemiplegia were more common in those ≥16 years old, compared with those <16 (P = 0.0095), even with a specific mutation (p.D801N; P = 0.045). Dynamic, beat-to-beat or electrocardiogram-to-electrocardiogram, changes were noted, suggesting the prevalence of abnormalities was underestimated. Electrocardiogram changes occurred independently of seizures or plegic episodes. Electrocardiogram abnormalities are common in alternating hemiplegia, have characteristics reflecting those of inherited cardiac channelopathies and most likely amount to impaired repolarization reserve. The dynamic electrocardiogram and neurological features point to periodic systemic decompensation in ATP1A3-expressing organs. Cardiac dysfunction may account for some of the unexplained premature mortality of alternating hemiplegia. Systematic cardiac investigation is warranted in alternating hemiplegia of childhood, as cardiac arrhythmic morbidity and mortality are potentially preventable.

Thioredoxin Reductase 2 (TXNRD2) mutation associated with familial glucocorticoid deficiency (FGD)

CONTEXT

Classic ACTH resistance, due to disruption of ACTH signaling, accounts for the majority of cases of familial glucocorticoid deficiency (FGD). Recently FGD cases caused by mutations in the mitochondrial antioxidant, nicotinamide nucleotide transhydrogenase, have highlighted the importance of redox regulation in steroidogenesis.

OBJECTIVE

We hypothesized that other components of mitochondrial antioxidant systems would be good candidates in the etiology of FGD.

DESIGN

Whole-exome sequencing was performed on three related patients, and segregation of putative causal variants confirmed by Sanger sequencing of all family members. A TXNRD2-knockdown H295R cell line was created to investigate redox homeostasis.

SETTING

The study was conducted on patients from three pediatric centers in the United Kingdom.

PATIENTS

Seven individuals from a consanguineous Kashmiri kindred, six of whom presented with FGD between 0.1 and 10.8 years, participated in the study.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURE

Identification and functional interrogation of a novel homozygous mutation segregating with the disease trait were measured.

RESULTS

A stop gain mutation, p.Y447X in TXNRD2, encoding the mitochondrial selenoprotein thioredoxin reductase 2 (TXNRD2) was identified and segregated with disease in this extended kindred. RT-PCR and Western blotting revealed complete absence of TXNRD2 in patients homozygous for the mutation. TXNRD2 deficiency leads to impaired redox homeostasis in a human adrenocortical cell line.

CONCLUSION

In contrast to the Txnrd2-knockout mouse model, in which embryonic lethality as a consequence of hematopoietic and cardiac defects is described, absence of TXNRD2 in humans leads to glucocorticoid deficiency. This is the first report of a homozygous mutation in any component of the thioredoxin antioxidant system leading to inherited disease in humans.

Cardiac disease in adolescents with delayed diagnosis of vertically acquired HIV infection

BACKGROUND

At least one-third of human immunodeficiency virus (HIV)-infected infants survive to adolescence even without antiretroviral therapy (ART), but are at high risk of complications including cardiac disease. We investigated the characteristics of cardiac disease among adolescents with HIV infection diagnosed in late childhood who were receiving ambulatory HIV care in Harare, Zimbabwe.

METHODS

Consecutive adolescents with vertically acquired HIV attending 2 HIV outpatient treatment clinics were studied. Assessment included clinical history and examination, and 2-dimensional, M-mode, pulsed- and continuous-wave Doppler echocardiography.

RESULTS

Of 110 participants (47% male; median age, 15 years; interquartile range, 12-17 years), 78 (71%) were taking ART. Exertional dyspnea, chest pain, palpitations, and ankle swelling were reported by 47 (43%), 43 (39%), 10 (9%), and 7 (6%), respectively. The New York Heart Association score was ≥ 2 in 41 participants (37%). Echocardiography showed that 74 participants (67%) had left ventricular (LV; septal and/or free wall) hypertrophy and 27 (24%) had evidence of impaired LV relaxation or restrictive LV physiology. The estimated pulmonary artery systolic pressure (ePASP) was >30 mm Hg in 4 participants (3.6%); of these 2 also had right ventricular (RV) dilatation. Another 32 participants (29%), without elevated ePASP, had isolated RV dilatation.

CONCLUSIONS

A significant burden of cardiac disease was seen among adolescents with vertically acquired HIV infection. More than half were asymptomatic yet had significant echocardiographic abnormalities. These findings highlight the need to screen this population in order to better define the geography, natural history, etiopathogenic mechanisms, and management (including the timing and choice of optimal therapeutic ART and cardiac drug interventions) to prevent development and/or progression of HIV-associated cardiac disease.

Idiopathic restrictive cardiomyopathy in children is caused by mutations in cardiac sarcomere protein genes

BACKGROUND

Restrictive cardiomyopathy (RCM) is rare in childhood, but has a grave prognosis. The cause of disease in most cases is unknown.

OBJECTIVE

To determine the prevalence of sarcomere protein gene mutations in children with idiopathic RCM.

METHODS

Twelve patients (9 female, mean age 5.1 years) with idiopathic RCM referred between 1991 and August 2006 underwent detailed clinical and genetic evaluation. Nine had received cardiac transplants at the time of the study. The entire coding sequences of the genes encoding eight cardiac sarcomere proteins and desmin were screened for mutations. Familial evaluation was performed on first-degree relatives.

RESULTS

Four patients (33%) had a family history of cardiomyopathy: RCM (n = 2); dilated cardiomyopathy (n = 1) and left ventricular non-compaction (n = 1). Sarcomere protein gene mutations were identified in four patients (33%): 2 in the cardiac troponin I gene (TNNI3) and 1 each in the troponin T (TNNT2) and alpha-cardiac actin (ACTC) genes. Two were de novo mutations and 3 were new mutations. All mutations occurred in functionally important and conserved regions of the genes.

CONCLUSIONS

Sarcomere protein gene mutations are an important cause of idiopathic RCM in childhood. We describe the first mutation in ACTC in familial RCM. The identification of RCM in a child should prompt consideration of sarcomere protein disease as a possible cause and warrants clinical evaluation of the family.

B-type natriuretic peptide predicts disease severity in children with hypertrophic cardiomyopathy

BACKGROUND

In adults with hypertrophic cardiomyopathy (HCM), plasma B-type natriuretic peptide (BNP) levels correlate with dyspnoea class and other markers of disease severity. In children with HCM, symptoms are a poor guide to disease severity and no studies have evaluated the clinical utility of BNP testing.

OBJECTIVE

To assess the relation of BNP levels to symptoms and markers of disease severity in children with HCM.

METHODS

Forty-four consecutive patients with HCM (27 male, age <or=17 years (median 13.6) underwent assessment of plasma BNP. Clinical evaluation of patients was carried out, including ECG, echocardiography and tissue Doppler imaging.

RESULTS

BNP levels correlated with maximal left ventricular (LV) wall thickness (r(s) = 0.631, p<0.001), resting LV outflow tract gradient (r(s) = 0.611, p<0.001), transmitral E/septal Ea (E/Ea(s)) ratio (r(s) = 0.770, p<0.001) and percentage predicted maximum VO(2) (r(s) = -0.390, p = 0.025); there was no relation between BNP and heart failure symptoms. BNP levels were higher in patients who had undergone implantation of an internal cardioverter-defibrillator than in those who had not (309 (interquartile range (IQR) 181-391) vs 50 (IQR 18-188) pg/ml, p = 0.001). BNP was independently associated with E/Ea(s) (r(s) = 0.632, p<0.001) and maximal LV wall thickness (r(s) = 0.412, p = 0.008) on multivariate analysis. At a cut-off point of 50 pg/ml, BNP had a positive predictive value of 93% and a negative predictive value of 80% for predicting E/Ea(s) >10 (area under the receiver operator characteristic curve = 0.875 (p<0.001)).

CONCLUSIONS

BNP levels correlate with non-invasive parameters of disease severity in children with HCM, including measures of raised LV filling pressures. For patients in whom evaluation of symptoms is difficult, BNP may be a useful additional tool in the assessment of disease severity.

Can atrioventricular septal defects exist with intact septal structures?

The hallmark of an atrioventricular septal defect (AVSD) is a common atrioventricular junction, giving rise to a trileaflet left atrioventricular valve. AVSDs have the potential for interatrial shunting alone, interventricular shunting alone, or both. AVSDs without interatrial or interventricular communications have been identified at postmortem examination, but there are no reports of AVSDs with intact septal structures diagnosed in life. Six patients are described with AVSD and intact atrial and ventricular septa diagnosed echocardiographically. This report shows that AVSDs can exist without interatrial or interventricular communications and that the characteristic feature of this condition, the common atrioventricular junction with a trileaflet left atrioventricular valve, can be diagnosed in life by using cross sectional echocardiography. AVSDs with intact septal structures may be more common than previously described.