Strategies for preventing arrhythmic sudden death in adult congenital heart disease

Arrhythmic sudden cardiac death (SCD) remains a major cause of late mortality in adults with congenital heart disease (ACHD), second only to heart failure. Risk prediction is challenging due to the heterogeneity of underlying defects and surgical histories. This review summarizes contemporary evidence on arrhythmic SCD prevention in ACHD, focusing on lesion-specific risk stratification, device-based therapies, and emerging technologies. Traditional markers-ventricular dysfunction, QRS prolongation, and prior arrhythmias-show limited predictive value. Recent models such as PREVENTION-ACHD and the Spanish ACHD Network score offer structured but evolving approaches to individualized risk assessment. Cardiac MRI-derived fibrosis quantification, electro-anatomical mapping, and machine-learning-based tools hold promise for refined prediction. Implantable cardioverter-defibrillators (ICDs) remain the cornerstone of secondary prevention, while subcutaneous ICDs and emerging extravascular systems mitigate lead-related complications. The wearable cardioverter-defibrillator offers a temporary protective option in high-risk patients awaiting definitive therapy. Catheter ablation-particularly in repaired Tetralogy of Fallot-can modify arrhythmic substrates, whereas bradyarrhythmias require vigilant monitoring and timely pacing interventions. In conclusion, effective prevention of arrhythmic SCD in ACHD demands a multidisciplinary, lesion-specific approach integrating advanced imaging, device innovation, and personalized risk modelling. Ongoing refinement of predictive tools and interventional strategies will be crucial to reduce mortality in this growing population.