Validation of the HCM Risk-SCD model in patients with hypertrophic cardiomyopathy and future perspectives

Abstract

Abstract Background/Introduction The fact that hypertrophic cardiomyopathy (HCM) is associated with sudden cardiac death (SCD) due to malignant ventricular arrhythmias underlies its clinical importance (1). SCD in patients with HCM is often an unpredictable event, occurring without previous warning signs or symptoms, and is most common in the young middle-aged group (2). The greatest dilemma in the management of HCM patients is to identify the high-risk population for SCD. The HCM risk- SCD model provides a useful convenience in determining the risk of SCD in patients with HCM even though some patients with low-risk scores still remain at risk of SCD (3). These results have increased the interest in additional strategies to improve the existing risk model. Purpose Hence, the aim of our study was to assess the performance of HCM Risk-SCD in a large series of consecutive patients with HCM who had been followed up in a tertiary centre. Methods The study population consisted of 389 consecutive HCM patients who had been followed up between 2004 and 2021. Demographic and clinical characteristics estimated 5-year risk using the HCM Risk-SCD model were compiled and survival data were collected during follow-up. Patients were divided into 2 groups according to their long-term survival and HCM risk-SCD scores of these two groups were compared. Results The long-term mortality was observed in 47 patients out of 389 patients in the mean follow-up of 55.5 ± 12.7 months. The mean HCM Risk-SCD of surviving patients was significantly lower than that of non-survivors (1.8% vs. 3.0%, p<0.001). The HCM Risk-SCD score was above 6% in 9 (2.6%) survivors and 9 (19.1%) non-survivors (p<0.001). Considering the Kaplan-Meier curve based on the 6% HCM Risk-SCD score, patients at ≥6% risk also had a significantly higher long-term risk of death compared to those with <6% (log-rank test value: 33.72, p<0.001) (Figure 1). The ROC curve based on the HCM Risk-SCD score had 61% sensitivity and 61% specificity for risk for 2.0%, 38% sensitivity and 99% specificity for ≥4%, 17% sensitivity and 99% specificity for ≥6% (Figure 2). Conclusion(s) In conclusion, the current study demonstrates that the HCM risk-SCD model, while easily calculable and clinically useful, does not reliably identify a significant subset of patients with HCM who will potentially be at lifetime risk of SCD. Identifying patients with hypertrophic cardiomyopathy at high risk for SCD who deserve ICD therapy is a critical management priority. A new risk algorithm that can detect the SCD risk of HCM patients with higher sensitivity is needed.Figure 1Figure 2