Pan-Canadian Registry, Pan-System Disease: Rethinking Fontan Pathobiology

I congratulate Roy et al. on establishing CANFON, a national Canadian longitudinal cohort spanning pediatric and adult Fontan patients, at a time when Fontan palliation has extended survival into adulthood(1). Patients with Fontan circulation invariably develop progressive multi-organ dysfunction – frailty, exercise intolerance, chronic hepatic congestion and fibrosis, renal impairment, lymphatic and metabolic derangements – yet the unifying mechanisms remain elusive. Echoing the 2019 American Heart Association (AHA) Statement’s emphasis on Fontan-associated complications, a major knowledge gap persists in identifying shared biochemical abnormalities driving this cascade.