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

Abstract

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.

A Validated Model for Sudden Cardiac Death Risk Prediction in Pediatric Hypertrophic Cardiomyopathy

“…The incidence of sudden cardiac death in pediatric HCM is significantly higher than in adults. 28 The 5-year risk of a SCD event in our study was 9.1%. However, only 25% received an ICD that was able to abort the event.…”

“… 20 , 25 – 27 A recent study from the United Kingdom reported on the performance of a SCD risk prediction model for pediatric HCM developed using 5 preselected clinical variables with a c-statistic of 0.69, but this model has not been externally validated. 28 The lack of evidence-based decision support for SCD risk prediction in childhood HCM has been identified as an important practice gap.…”

The Public Health Burden of Cardiomyopathies: Insights from a Nationwide Inpatient Study

“…There is a definite interest in launching specific action plans for cardiomyopathies in order to improve early diagnosis, therapeutics, and prevention of event recurrence [4]. The better identification of these patients is especially important in the context of recent progress in prognosis stratification [28][29][30], along with the development of recent innovative therapeutics based on new small molecules or gene-editing approaches [31]. Our results suggest that we should focus especially on patients with dilated cardiomyopathy, who are the leading reason for hospitalizations, heart transplants, and defibrillator implantations.…”

Sudden Cardiac Death in Children Affected by Cardiomyopathies: An Update on Risk Factors and Indications at Transvenous or Subcutaneous Implantable Defibrillators

“…Indeed, even if there are some evidences pointing out that effective septal reduction may reduce SCD risk in adults, conclusive results are not yet available (44). Data are even more scarce in the pediatric population, in which, at variance to the adult population, the LVOT gradient is not consistently linked to SCD risk (45).…”

“…Along with these major criteria, left atrial diameter has been pointed out as an additional important risk factor (28). More recently, Norrish et al (45) developed a novel risk prediction model for sudden cardiac death in HCM children through a retrospective, multicenter, longitudinal cohort study on 1,024 patients below 16 years and the most predictive variables included in the model were unexplained syncope, degree of hypertrophy, LA diameter and NSVT, while the maximal LVOT gradient appeared to be inversely related with SCD risk, a data that clearly needs further investigation. Finally, Maurizi et al (29) described the long-term outcome of 100 pediatric patients with HCM, with a 40-year follow-up.…”