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Hypertrophic cardiomyopathy (HCM) is associated with adverse left ventricular (LV) remodeling causing dysfunction and malignant arrhythmias. Severely affected patients present with disease onset during childhood and sudden cardiac death risk (SCD) stratification is of the highest importance in this cohort. This study aimed to investigate genotype-phenotype association regarding clinical outcome and disease progression in pediatric onset HCM. Medical charts from forty-nine patients with pediatric HCM who had undergone genetic testing were reviewed for retrospective analysis. Demographic, clinical, transthoracic echocardiographic, electrocardiographic, long-term electrocardiogram, cardiopulmonary exercise test, cardiac magnetic resonance, and medication data were recorded. Childhood onset HCM was diagnosed in 29 males and 20 females. Median age at last follow-up was 18.7 years (range 2.6-51.7 years) with a median follow-up time since diagnosis of 8.5 years (range 0.2-38.0 years). Comparison of patients carrying mutations in distinct genes and comparison of genotype-negative with genotype-positive individuals, revealed no differences in functional classification, LV morphology, hypertrophy, systolic and diastolic function, fibrosis and cardiac medication. Patients with compound mutations had a significantly higher risk for major arrhythmic events than a single-mutation carrier. No association between affected genes and disease severity or progression was identified in this cohort.

Objectives: The aim of this study was to assess the effect of surgical septal myectomy performed during early childhood for severe, drug-refractory hypertrophic cardiomyopathy with left ventricular outflow tract obstruction on the extent of septal myocardial extracellular volume fraction and the potential risk of developing atrioventricular cardiac conduction system disease., Methods: In this retrospective study, data from 30 patients with a confirmed diagnosis of childhood-onset hypertrophic cardiomyopathy were reviewed including cardiovascular magnetic resonance (CMR) with myocardial T1 mapping and late gadolinium enhancement, histopathology of myocardial specimens, transthoracic echocardiography, electrocardiography, 24-h Holter and cardiopulmonary exercise testing. Eighteen patients without were compared to 12 patients with prior septal myectomy performed during childhood (non-operated versus myectomy patients)., Results: Late gadolinium enhancement on CMR as a correlate for focal myocardial fibrosis was found in 53% of patients, predominantly located in the septal region, with no difference between groups. As compared to non-operated patients, those after myectomy showed a similar amount of total and septal extracellular volume fraction, as calculated from pre- and post-contrast CMR T1 mapping, which is a correlate for diffuse interstitial myocardial fibrosis. PQ-intervals or the occurrence of higher degree conduction system disease were equal between the 2 groups., Conclusions: Data from CMR and electrocardiography suggest that surgical septal myectomy performed during early childhood for severe obstructive hypertrophic cardiomyopathy does not cause an increased septal extracellular volume fraction or delayed atrioventricular conduction time on long-term follow-up., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Background: To compare outcome and cardiac pathology between patients with Noonan syndrome (N-HCM) and sarcomere protein-associated (S-HCM) childhood onset hypertrophic cardiomyopathy (HCM)., Methods: Clinical data were recorded from medical charts. Primary endpoint was survival. Secondary endpoints were survival without hospitalization, without intervention or without arrhythmic events. Functional clinical status and results from genetic testing, imaging, electrocardiographic (ECG) studies, cardiopulmonary exercise testing (CPET) and histopathology were compared between groups., Results: Childhood HCM was diagnosed in 29 N-HCM and 34 S-HCM patients. Follow-up time was greater than 10 years in more than half of all patients. Mortality was below 7% and not different between groups. Children with N-HCM presented at a younger age and there was less time of survival without hospitalization for heart failure or intervention in N-HCM compared to S-HCM patients. Clinical functional status improved over time in N-HCM patients. On long-term follow-up, left ventricular posterior wall thickness indexed to body surface area decreased in N-HCM and increased in S-HCM patients. There was a trend to lower risk for severe arrhythmic events in N-HCM patients and only S-HCM individuals received an implantable cardioverter-defibrillator. There were no differences between groups in ventricular function, ECG and CPET parameters. Myocardial fibrosis as assessed by histopathology of myocardial specimens and cardiovascular magnetic resonance with late gadolinium enhancement or T1 mapping was present in both groups., Conclusions: When compared to S-HCM patients, children with N-HCM have increased morbidity during early disease course, but favorable long-term outcome with low mortality, stagnation of myocardial hypertrophy, and low risk for malignant arrhythmias., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare., (2019 Cardiovascular Diagnosis and Therapy. All rights reserved.)

Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.

Objectives: Surgical septal myectomy is performed to relieve left ventricular outflow tract narrowing in severe drug-refractory obstructive hypertrophic cardiomyopathy. The objective of this study was to assess the perioperative and long-term clinical outcome of this procedure performed during infancy., Methods: Clinical, transthoracic echocardiographic, electrocardiographic, 24-h Holter, cardiopulmonary exercise test and genetic data were extracted by medical record review. A subset of patients underwent additional prospective detailed clinical evaluation including cardiac magnetic resonance imaging with contrast., Results: Surgery was performed in 23 paediatric patients between 1978 and 2015 at the German Heart Centre Munich. Twelve patients had undergone surgery during infancy (≤ 1 year) (Group A), 11 between 1 and 18 years of age (Group B). The underlying genetic diagnosis was Noonan syndrome spectrum and non-syndromic hypertrophic cardiomyopathy. As compared to Group B, patients in Group A showed more concomitant cardiac procedures and received more homologous transfusions. One perioperative death occurred in Group A, and none in Group B. Two patients in Group A but no patient in Group B required redo septal myectomy. The long-term clinical outcome was similar between the 2 groups. One patient in Group B required cardioverter-defibrillator/pacemaker implantation for higher degree atrioventricular block and none in Group A. There was no evidence of differences in myocardial fibrosis between groups on long-term follow-up magnetic resonance imaging., Conclusions: Surgical septal myectomy can be performed safely during infancy with favourable perioperative and long-term clinical outcome but with a trend towards a higher reoperation rate later in life., (© The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)