Occluded fenestration is associated with improved long-term outcomes in patients undergoing the fenestrated Fontan operation.

Objective: The modified Fontan operation, a palliative approach for patients with single ventricular circulation, often incorporates a fenestration to facilitate postoperative management. Postoperative fenestration closure sometimes is performed to mitigate potential risks such as low oxygen saturation. However, the benefits and potential risks of this procedure remain under investigation.

Methods: A retrospective, propensity score-matching study was conducted at the National Taiwan University Children's Hospital. It included all patients who underwent their first fenestrated modified Fontan procedure between February 1998 and July 2020. The primary objective was to assess the incidence of death, Fontan takedown, and heart transplantation. Major adverse cardiovascular events were considered as a secondary outcome.

Results: The study comprised 173 patients (male/female 100/73), with a median operation age of 4.6 years and a median follow-up of 10.4 years (interquartile range, 6.2-14.0 years) after operation. At the latest follow-up, fenestration was occluded in 74 patients (42.8%), with 29 undergoing transcatheter closure and 45 experiencing spontaneous occlusion. After propensity score matching, patients with occluded fenestration demonstrated significantly better event-free survival (15-year survival 95.3% vs 78.6%, P = .047), although the intention-to-treat fenestration closure group showed similar outcomes compared with the natural course group. High recent N-terminal pro-B-type natriuretic peptide and Fontan pressure emerged as critical risk factors for worse event-free survival and major adverse cardiovascular events. The cutoff points of N-terminal pro-B-type natriuretic peptide and Fontan pressure were 467.7 pg/mL and 18 mm Hg, respectively.

Conclusions: Patients with occluded fenestration exhibited superior event-free survival. Fenestration closure is a feasible strategy to enhance oxygen saturation without elevating Fontan pressure.