The long-term effect of the Fontan fenestration on clinical outcomes: A FORCE registry study

Background: The long-term effect of open fenestration in Fontan patients is unclear, leading to wide practice variation of fenestration creation and closure. We evaluated the long-term outcomes of the fenestration using data from the Fontan Outcome Registry using Cardiac Magnetic Resonance Examinations (FORCE) Study. Methods: Patients were categorized by fenestration status determined by post-Fontan cardiac magnetic resonance imaging (CMR) as open fenestration, nonfenestrated Fontan, spontaneous closure, and device closure. The primary outcome was the time from the CMR to the earliest event of death, listing or receiving a heart transplant, plastic bronchitis, or protein-losing enteropathy. The association between fenestration status and the outcome measure was evaluated using Cox proportional hazard models, adjusted for patients’ clinical and CMR characteristics. Results: The cohort consisted of 2,923 patients with a median age at CMR of 14.3 years. Patients with open fenestration were younger and less likely to have a systemic left ventricle. Nonfenestrated Fontan patients were more likely to have a systemic left ventricle and lower indexed single ventricle end-diastolic volume (SVEDVi). An open fenestration was associated with adverse outcomes adjusted for clinical variables (hazard ratio 1.70, 95% CI [1.09, 2.64], P =.02). The association was no longer significant when adjusted for CMR variables, while every 10 mL/m² increase in SVEDVi was associated with a 5% increase in the hazard of clinical outcomes (P <.0001). Conclusions: Open fenestration is associated with adverse outcomes when adjusted for clinical characteristics. The association disappeared when additionally adjusting for CMR variables. The current practice of fenestration closure in selected patients leads to comparable outcomes with spontaneous closure and nonfenestrated Fontan.