Abstract
AimsSudden cardiac death (SCD) is the most common cause of death in children with hypertrophic cardiomyopathy (HCM). The European Society of Cardiology (ESC) recommends consideration of an implantable cardioverter-defibrillator (ICD) if two or more clinical risk factors (RFs) are present, but this approach to risk stratification has not been formally validated.Methods and resultsFour hundred and eleven paediatric HCM patients were assessed for four clinical RFs in accordance with current ESC recommendations: severe left ventricular hypertrophy, unexplained syncope, non-sustained ventricular tachycardia, and family history of SCD. The primary endpoint was a composite outcome of SCD or an equivalent event (aborted cardiac arrest, appropriate ICD therapy, or sustained ventricular tachycardia), defined as a major arrhythmic cardiac event (MACE). Over a follow-up period of 2890 patient years (median 5.5 years), MACE occurred in 21 patients (7.5%) with 0 RFs, 19 (16.8%) with 1 RFs, and 3 (18.8%) with 2 or more RFs. Corresponding incidence rates were 1.13 [95% confidence interval (CI) 0.7–1.73], 2.07 (95% CI 1.25–3.23), and 2.52 (95% CI 0.53–7.35) per 100 patient years at risk. Patients with two or more RFs did not have a higher incidence of MACE (log-rank test P = 0.34), with a positive and negative predictive value of 19% and 90%, respectively. The C-statistic was 0.62 (95% CI 0.52–0.72) at 5 years.ConclusionsThe incidence of MACE is higher for patients with increasing numbers of clinical RFs. However, the current ESC guidelines have a low ability to discriminate between high- and low-risk individuals.
Highlights
Hypertrophic cardiomyopathy (HCM) is the second commonest cardiomyopathy occurring during childhood, with an estimated annual incidence of 0.24–0.47 per 100 000 and prevalence of 2.7 per 100 000.1–3 Early reports suggested a very poor prognosis in childhood HCM,[4] but more recent population-based and registry studies have reported annual mortality rates between 1% and 2.5%.5–8 The most common cause of mortality outside of infancy is sudden cardiac death (SCD),[6] making risk stratification for arrhythmic events one of the cornerstones of the management of children with HCM
implantable cardioverter-defibrillator (ICD) have been shown to be effective at aborting malignant arrhythmias in children with HCM,[10,11] these younger patients experience a higher rate of complications than adults,[10] reinforcing the need to robustly identify individuals most likely to benefit from device implantation
The majority of patients (69%) in this cohort had none of the traditional clinical risk factors (RFs) for SCD historically used for risk stratification in adults, and only a small number of patients met the European Society of Cardiology (ESC) threshold for ICD implantation (16 patients, 3.9%)
Summary
Hypertrophic cardiomyopathy (HCM) is the second commonest cardiomyopathy occurring during childhood, with an estimated annual incidence of 0.24–0.47 per 100 000 and prevalence of 2.7 per 100 000.1–3 Early reports suggested a very poor prognosis in childhood HCM,[4] but more recent population-based and registry studies have reported annual mortality rates between 1% and 2.5%.5–8 The most common cause of mortality outside of infancy is sudden cardiac death (SCD),[6] making risk stratification for arrhythmic events one of the cornerstones of the management of children with HCM. The most common cause of mortality outside of infancy is sudden cardiac death (SCD),[6] making risk stratification for arrhythmic events one of the cornerstones of the management of children with HCM. The European Society of Cardiology (ESC) guidelines[9] recommend the use of four clinical risk factors (RFs) to stratify risk in children with HCM: unexplained syncope, family history of SCD, extreme left ventricular hypertrophy (LVH), and non-sustained ventricular tachycardia (NSVT) on ambulatory electrocardiography (ECG) recordings. ICDs have been shown to be effective at aborting malignant arrhythmias in children with HCM,[10,11] these younger patients experience a higher rate of complications than adults,[10] reinforcing the need to robustly identify individuals most likely to benefit from device implantation. This study sought to perform the first validation of the 2014 ESC guidelines in a cohort of childhood HCM from the UK
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