Sudden cardiac death in congenital heart disease

Sudden cardiac death (SCD) accounts for up to 25% of deaths in patients with congenital heart disease (CHD). To date, research has largely been driven by observational studies and real-world experience. Drawbacks include varying definitions, incomplete taxonomy that considers SCD as a unitary diagnosis as opposed to a terminal event with diverse causes, inconsistent outcome ascertainment, and limited data granularity. Notwithstanding these constraints, identified higher-risk substrates include tetralogy of Fallot, transposition of the great arteries, cyanotic heart disease, Ebstein anomaly, and Fontan circulation. Without autopsies, it is often impossible to distinguish SCD from non-cardiac sudden deaths. Asystole and pulseless electrical activity account for a high proportion of SCDs, particularly in patients with heart failure. High-quality cardiopulmonary resuscitation is essential to improve outcomes. Pulmonary hypertension and CHD complexity are associated with lower likelihood of successful resuscitation. Risk stratification for primary prevention implantable cardioverter-defibrillators (ICDs) should consider the probability of SCD due to a shockable rhythm, competing causes of mortality, complications of ICD therapy, and associated costs. Risk scores to better estimate probabilities of SCD and CHD-specific guidelines and consensus-based recommendations have been proposed. The subcutaneous ICD has emerged as an attractive alternative to transvenous systems in those with vascular access limitations, prior device infections, intra-cardiac shunts, or a Fontan circulation. Further improving SCD-related outcomes will require a multidimensional approach to research that addresses disease processes and triggers, taxonomy to better reflect underlying pathophysiology, high-risk features, early warning signs, access to high-quality cardiopulmonary resuscitation and specialized care, and preventive therapies tailored to underlying mechanisms.

Automated summary

Sudden cardiac death (SCD) is a significant cause of death in patients with congenital heart disease (CHD). Current research is mainly based on observational studies and clinical experience, with some limitations. Certain higher-risk underlying diseases have been identified, but distinguishing SCD from non-cardiac sudden deaths is often challenging without autopsies. High-quality cardiopulmonary resuscitation is crucial for improving outcomes. Risk stratification for preventing SCD should consider the probability of shockable rhythm, other causes of death, complications of implantable cardioverter-defibrillator (ICD) therapy, and associated costs. Risk scores and specific guidelines and recommendations for CHD have been proposed. Additionally, the subcutaneous ICD is an attractive alternative. Further improvement in SCD-related outcomes requires a multidimensional research approach.