Predicting the unpredictable: sudden cardiac death risk in cardiomyopathies

This editorial refers to ‘Risk Models for Sudden Cardiac Death in Cardiomyopathies: Clinical, Methodological and Ethical Challenges’, by A. S. Antonopoulos et al., https://doi.org/10.1093/ejhf/xuag161. Despite substantial advances in cardiovascular medicine, sudden cardiac death (SCD) remains one of the most consequential and least predictable clinical events in patients with cardiomyopathies. Its incidence ranges from 0.15% to 0.7% per year1 and implantable cardioverter-defibrillators (ICDs) can effectively prevent SCD by terminating malignant ventricular arrhythmias. However, ICD treatment comes with a fundamental challenge: accurately identifying patients who will benefit clinically from primary prevention ICD implantation, while avoiding unnecessary procedures and considering device-related risks. Historically, risk stratification has relied heavily on left ventricular ejection fraction (LVEF). While reduced LVEF is associated with increased arrhythmic risk, its limitations as a discriminatory marker are well established as demonstrated in trials like DANISH.2 A substantial proportion of SCD events occurs in patients with only mildly reduced or even preserved systolic function, whereas many patients with severely impaired LVEF die from non-arrhythmic causes, particularly progressive heart failure and other comorbidities. These discrepancies underscore a central limitation of threshold-based approaches that inadequately capture the multidimensional nature of arrhythmic risk.