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Screening in Child First-Degree Relatives for HCM
Study Questions:
What is the yield of clinical screening for hypertrophic cardiomyopathy (HCM) in first-degree children and adolescent relatives?
Methods:
This was a retrospective observational study of a pediatric cohort aged ≤18 years referred from 1994 to 2017 to the inherited cardiovascular disease program at a large, tertiary care center in the United Kingdom for family screening. Patients were screened every 12-24 months during preadolescence and every 6-12 months during adolescence using standard 2D echocardiography with Doppler in addition to clinical symptoms, exam, and resting and ambulatory electrocardiogram (ECG). Data on genetic testing were collected in those with this available.
Results:
A total of 1,198 pediatric patients from 594 families were referred for screening. Mean age at referral was 7.9 ± 4.7 years. Over a median follow-up period of 3.5 years, 57 (4.7%) patients were diagnosed with HCM from 8.1% of referred families. Median age at diagnosis was 10 years (interquartile range [IQR], 4-13 years). At baseline evaluation, 32 met criteria for HCM and 25 were diagnosed with HCM at follow-up.
Genetic testing was performed in 192 families (32%) with a pathogenic or likely pathogenic mutation identified in 122 families (64%). In the 57 pediatric patients diagnosed with HCM during screening, 39 patients (68%) had genetic testing performed with pathogenic or likely pathogenic mutation identified in 27 (69%) patients.
Patients diagnosed with HCM at screening were followed-up for a median of 7.3 years (IQR, 2.7-12.8) with nine patients following-up for <1 year. During follow-up, 17 patients reported cardiac symptoms, 18 were started on medications, two patients underwent myectomy, four underwent an electrophysiology study, 14 received an implantable cardioverter-defibrillator (ICD), one died at age 24 due to a stroke, and one patient developed end-stage HCM needing a heart transplant at age 15.
Conclusions:
In a large cohort of pediatric patients referred for HCM screening at a large, tertiary care center, clinical screening with an echo and ECG yielded an HCM diagnosis in nearly 5% of patients in 8% of families. Furthermore, median age of HCM diagnosis at screening was 10 years. At follow-up, over one third of patients who were diagnosed with HCM during screening received HCM therapies.
Perspective:
Current guidelines recommend cascade family screening to diagnose asymptomatic HCM in first-degree relatives after the age of 10 years unless there is a malignant family history, symptoms, or participation in competitive sports. In this prospective study, median age for HCM diagnosis was 10 years, suggesting a large proportion of pediatric patients screened positive below the guideline-recommended cut-off. Furthermore, for patients who screened in, over one third received HCM therapies in the form of medications or ICD, highlighting the importance of early diagnosis. Follow-up showed that end-stage HCM was rare with only one patient requiring a cardiac transplant.
Limitations of this study include its retrospective design and the cohort predated introduction of HCM genetic testing. Nonetheless, it reflects real-world clinical practice with long-term follow-up in a pediatric HCM population. Furthermore, yield of clinical testing in this study is lower since it includes both genotype-positive and genotype-negative patients. Future studies should evaluate yield and cost efficiency of integrating genetic testing for HCM screening.
Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Cardiovascular Care Team, Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Aortic Surgery, Cardiac Surgery and Arrhythmias, Cardiac Surgery and CHD and Pediatrics, Cardiac Surgery and Heart Failure, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Imaging, CHD and Pediatrics and Interventions, Acute Heart Failure, Heart Transplant, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound
Keywords: Adolescent, Cardiomyopathy, Hypertrophic, Defibrillators, Implantable, Echocardiography, Electrocardiography, Electrophysiology, Genetic Testing, Genotype, Heart Failure, Heart Transplantation, Mutation, Pediatrics, Stroke, Tertiary Care Centers
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