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.

中文翻译：

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用于预测儿童肥厚型心肌病心源性猝死的 HCM Risk-Kids 模型的外部验证。

目的 心源性猝死（SCD）是儿童肥厚性心肌病（HCM）最常见的死亡方式。新开发的 HCM Risk-Kids 模型为临床医生提供个性化的风险评估。本研究的目的是在大型独立、多中心患者队列中对模型进行外部验证。方法和结果 对 421 名 1-16 岁诊断为 HCM 的患者进行回顾性纵向队列研究，独立于 HCM 风险儿童发展和内部验证队列。从基线临床评估时开始收集 HCM Risk-Kids 预测变量（不明原因晕厥、非持续性室性心动过速、最大左心室壁厚度、左心房直径和左心室流出道梯度）的数据。评估了 HCM Risk-Kids 模型预测 5 年风险的性能。23 名患者 (5.4%) 在 5 年内达到 SCD 终点，总体发病率为每 100 患者年 2.03 例 [95% 置信区间 (CI) 1.48-2.78]。模型验证显示 Harrell 的 C 指数为 0.745 (95% CI 0.52-0.97)，Uno 的 C 指数为 0.714 (95% 0.58-0.85)，校准斜率为 1.15 (95% 0.51-1.80)。≥6% 的 5 年预测风险阈值确定了 17 起 (73.9%) SCD 事件，相应的 C 统计值为 0.702 (95% CI 0.60-0.81)。结论 本研究报告了 HCM Risk-Kids 模型在大量且不同地域的患者群体中的首次外部验证。5 年预测风险≥6%，识别了超过 70% 的事件，证实 HCM Risk-Kids 提供了一种对 HCM 儿童进行个性化风险预测和共同决策的方法。