Performance of HCM Risk-SCD in patients with ICD: insights from a brazilian population
I Raduan Brigo, F Fernandes, A Silva Martins, G J dos Santos Ferreira, F Cerqueira Matheus, M Ramos Dal Piaz, T Baptista Teixeira, M Goncalves Henriques Lizandro, A P de Morais Rodrigues Barros, M Martinelli Filho, V Machado Correa, J Novaes Cardoso, M de Oliveira Antunes, F Jose Alvarez Ramires, V Madrini JuniorAbstract
Background
The European Society of Cardiology (ESC) HCM Risk-SCD model is guideline-endorsed for sudden cardiac death (SCD) risk stratification in hypertrophic cardiomyopathy (HCM). However, its performance in ethnically diverse populations and in ICD-treated cohorts remains uncertain.
Purpose
To evaluate the discriminatory performance of the 5-year ESC HCM Risk-SCD score for predicting arrhythmic events in a real-world Brazilian HCM population with implantable cardioverter-defibrillators (ICDs).
Methods
We conducted a retrospective cohort study including 109 HCM patients with ICD implantation at the Heart Institute (InCor), in our university, a tertiary referral center specialized in cardiomyopathies. The primary endpoint was a composite of sudden cardiac death or appropriate ICD therapy. The ESC HCM Risk-SCD score was calculated in 107 patients based on available clinical data from medical records. The ESC HCM Risk-SCD score was analyzed as a continuous variable using receiver operating characteristic (ROC) analysis and categorically according to guideline-recommended strata: low (<4%), intermediate (4–6%), and high (>6%). Odds ratios (OR) with 95% confidence intervals (CI) were calculated.
Results
Mean age was 49 years, 51.38% were male, and mean follow-up was 10 years. ICD implantation was performed for primary prevention in 73.39% and secondary prevention in 26.61%. HCM Risk-SCD was calculable in 107 patients. Event rates were 40.0% in low-risk, 47.8% in intermediate-risk, and 24.1% in high-risk groups. Compared with low-risk patients, neither intermediate-risk (OR 1.38; 95% CI 0.52–3.66) nor high-risk (OR 0.48; 95% CI 0.17–1.31) categories were significantly associated with events. As a continuous predictor, the score demonstrated limited discriminatory capacity (AUC 0.47; 95% CI 0.36–0.58; p=0.67 vs 0.50).
Conclusions
In this Brazilian ICD-treated HCM cohort, the ESC HCM Risk-SCD model demonstrated limited discriminatory capacity for arrhythmic events. Event rates did not progressively increase across ESC risk categories, and high-risk patients did not exhibit higher event rates compared with lower-risk groups. Differences in population characteristics and ICD indication criteria may partially explain these findings. These results highlight the importance of careful interpretation of risk models in ethnically diverse and ICD-selected populations and support ongoing efforts to refine and contextualize risk stratification strategies in our setting.Figure 1