Congenital & Pediatric Heart Disease Scores

HCM Risk-Kids Calculator – Pediatric Hypertrophic Cardiomyopathy SCD Risk

Clinical calculation support · Verify results before clinical use

Pediatric HCM Risk Assessment

Enter baseline clinical and echocardiographic findings to estimate the 5-year risk using the HCM Risk-Kids model.

— 5-year risk

Eligibility and clinical context

The model was developed in children aged 16 years or younger and is not intended for infantile or syndromic/metabolic/neuromuscular HCM.

Age at baseline evaluation Years; supported model cohort: 1–16 years. Age is an eligibility check, not a model predictor.

Syndromic, metabolic, or neuromuscular HCM? Examples include RASopathy, inborn errors of metabolism, and neuromuscular disease.

Echocardiographic predictors

Use baseline measurements. Enter body-surface-area-adjusted pediatric z-scores from an appropriate validated reference dataset; do not enter raw millimetre measurements in the z-score fields.

Maximal wall thickness z-score Standard deviations from the reference population mean

Left atrial diameter z-score Standard deviations from the reference population mean

Maximal LVOT gradient mmHg; maximum at rest or with Valsalva using continuous-wave Doppler

Clinical predictors

Record findings present at or before the baseline evaluation.

Unexplained syncope

Transient loss of consciousness with no identifiable cause.

Yes

Non-sustained ventricular tachycardia (NSVT)

At least 3 consecutive ventricular beats at ≥120 bpm lasting less than 30 seconds on ambulatory ECG monitoring (minimum duration 24 hours).

Yes

— 5-year risk

Estimated 5-year risk

—

Clinical interpretation

This is a model-derived estimate, not an individualized treatment recommendation. A result at or above 6% has been used as a risk threshold in validation research; the 2023 ESC guideline notes HCM Risk-Kids >6% among potential pediatric SCD risk factors. ICD decisions require comprehensive specialist assessment and shared decision-making.

About HCM Risk-Kids

HCM Risk-Kids is a pediatric-specific model developed to estimate the 5-year risk of sudden cardiac death (SCD) or an equivalent arrhythmic event in children with hypertrophic cardiomyopathy. The development cohort included 1,024 patients aged 16 years or younger from 39 centres.

The model uses five predictors: maximal left ventricular wall thickness z-score, left atrial diameter z-score, maximal LVOT gradient, unexplained syncope, and NSVT. Age is used here only to check the model's intended age range; age is not included in the prognostic equation.

Model equation

5-year risk = 1 − 0.949437808^exp(PI)

PI = 0.2171364 × (MWT z-score − 11.09) − 0.0047562 × (MWT z-score² − 174.12) + 0.130365 × (LA z-score − 1.92) + 0.429624 × syncope + 0.1861694 × NSVT − 0.0065555 × (maximal LVOT gradient − 21.8).

Syncope and NSVT are coded as 0 = absent and 1 = present. The calculation uses unrounded input values; the displayed percentage is rounded to two decimal places.

Risk bands used in the development study

Predicted 5-year risk	Descriptive band
<2%	Lowest model risk band
2% to <4%	Lower-intermediate model risk band
4% to <6%	Upper-intermediate model risk band
≥6%	Threshold used in external validation research

Important limitations

Not intended for infantile presentation, syndromic HCM, inborn errors of metabolism, or neuromuscular disease.
Family history of SCD, genotype, LV systolic dysfunction, apical aneurysm, and CMR late gadolinium enhancement are not included in this equation.
Use z-scores calculated with suitable pediatric reference equations and body-surface-area adjustment. The calculator does not derive z-scores from raw measurements.
Do not use the estimate in isolation to decide on ICD implantation or to replace pediatric HCM specialist assessment.

References

Norrish G, Ding T, Field E, et al. Development of a Novel Risk Prediction Model for Sudden Cardiac Death in Childhood Hypertrophic Cardiomyopathy (HCM Risk-Kids). JAMA Cardiology. 2019;4(9):918–927. doi:10.1001/jamacardio.2019.2861. View publication

Norrish G, Ding T, Field E, et al. External validation of the HCM Risk-Kids model for predicting sudden cardiac death in childhood hypertrophic cardiomyopathy. European Journal of Preventive Cardiology. 2022;29(4):678–686. doi:10.1093/eurjpc/zwab181. View publication

Arbelo E, Protonotarios A, Gimeno JR, et al. 2023 ESC Guidelines for the management of cardiomyopathies. European Heart Journal. 2023;44(37):3503–3626. doi:10.1093/eurheartj/ehad194. View guideline

Ommen SR, Ho CY, Asif IM, et al. 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy. Journal of the American College of Cardiology. 2024. doi:10.1016/j.jacc.2024.02.014. View guideline

Clinical disclaimer: This calculator is intended for professional clinical and educational use in the appropriate pediatric HCM population. It provides a statistical estimate based on the published HCM Risk-Kids model and does not establish a diagnosis, determine an individual patient's complete risk profile, or prescribe treatment. Clinical decisions, including primary-prevention ICD consideration, should incorporate the full phenotype, family and genetic context, additional imaging and clinical risk markers, patient/family preferences, and specialist judgment.