Validation of the HCM Risk-SCD Model in a Chinese Hypertrophic Cardiomyopathy Cohort

<b>Background</b>: Hypertrophic cardiomyopathy (HCM) is associated with sudden cardiac death (SCD). The HCM Risk-SCD model has been widely used in Western populations, but its performance in Chinese patients remains unclear. <b>Methods</b>: This retrospective cohort study evaluated 534 HCM patients (348 males and 186 females) at Fuwai Hospital from 1992 to 2010. We calculated the HCM Risk-SCD score for each patient and categorized them into low-risk (<4%) and intermediate-high-risk (≥4%) groups. The primary endpoint was SCD events, defined as unexpected sudden death within one hour of symptom onset, successful resuscitation after cardiac arrest, appropriate ICD discharge, or sustained ventricular tachycardia. Model performance was assessed using Cox regression analysis, Kaplan-Meier survival analysis, ROC curve analysis, and subgroup analyses with interaction tests. <b>Results</b>: During a mean follow-up of 6.96 ± 4.16 years, 31 SCD events occurred. The intermediate-high-risk group had significantly higher SCD incidence than the low-risk group (8.68% vs. 3.42%, <i>p</i> = 0.01). This association remained significant after multivariate adjustment (HR 2.718, 95% CI: 1.264-5.848, <i>p</i> = 0.011). Kaplan-Meier analysis showed significant differences in SCD-free survival between risk strata (log-rank <i>p</i> = 0.01). The actual 5-year SCD event rate (4.31%) closely aligned with the model-predicted rate (4.65 ± 3.26%). ROC analysis demonstrated moderate discriminative ability in the overall population (AUC = 0.660, <i>p</i> = 0.003). The optimal cutoff value was 3.23 for the overall population. <b>Conclusions</b>: The HCM Risk-SCD model demonstrates acceptable performance in Chinese HCM patients.