The Fontan circulation: Arrhythmia is just one price we have to pay.

The Fontan circulation has transformed the outlook for patients with single-ventricle congenital heart disease, allowing survival into adolescence and adulthood for thousands who would otherwise not have survived. However, this success comes at the cost of a unique and complex physiology associated with multiple long-term complications, among which arrhythmia remains a major concern. In this invited commentary, the findings of a recent systematic review and meta-analysis comparing arrhythmia outcomes after extracardiac and intracardiac Fontan completion are discussed in the broader context of Fontan physiology. While extracardiac Fontan appears to be associated with a lower arrhythmia risk, the clinical significance of different rhythm disturbances and their impact on overall outcomes requires careful interpretation. Exercise limitation, hepatic issues, and quality of life are among the other important effects of Fontan circulation that should be taken into account in addition to arrhythmia. Ultimately, the choice of Fontan pathway should be guided by overall long-term benefits rather than arrhythmia risk alone, emphasizing the need for robust longitudinal data and collaborative registries to help future decision-making.