Pediatric Cardiology

Occluded fenestration is associated with improved long-term outcomes in patients undergoing the fenestrated Fontan operation. Lîm HK, Wu MH, Wang JK, Lin MT, Chen CA, Lu CW, Chen YS, Huang SC, Chiu SN.J Thorac Cardiovasc Surg. 2025 Jan 10:S0022-5223(25)00012-1. doi: 10.1016/j.jtcvs.2024.12.029. Online ahead of print. PMID: 39800273 Take home points: In a large longitudinal cohort from an Asian center, the occlusion of the fenestration(either spontaneous or transcatheter closure) of the Fontan circuit was associated with better event free survival Transcatheter fenestration closure was shown to be both safe and effective, with no major procedural complications reported. In patients post-Fontan, NT-proBNP ≥ 467.7 pg/mL and Fontan pressure ≥ 18 mm Hg were predictors of adverse outcomes. Commentary from Dr. Vimal Jayswal (Indiana, USA), editor of Pediatric & Fetal Cardiology Journal Watch.   The modified Fontan operation, a palliative approach for patients with single ventricular circulation, often incorporates a fenestration to facilitate postoperative management. Postoperative fenestration closure is sometimes performed to mitigate risks like low oxygen saturation and thromboembolism. However, the benefits and risks of this procedure remain under investigation. The decision to proceed with Fontan fenestration closure procedure involves a pre-closure hemodynamic evaluation, including measurement of Fontan pressure with or without the implementation of a balloon test occlusion. Lîm et al. make a valuable contribution by this study to distinguish the outcome disparities between patients with an occluded fenestration at the latest follow-up and those with a patent fenestration after the Fontan operation.  This analysis affirmed that occluded fenestration, whether spontaneous or induced, is associated with superior long-term survival in Fontan patients without significantly increasing Fontan pressures. Key findings: 1) Patients with an occluded fenestration exhibit better event-free survival compared with the patent fenestration group after the fenestrated modified Fontan operation. The event-free survival in the occluded fenestration group reaches 95.3% in 15 years, significantly surpassing the 78.6% in the patent fenestration group post-Fontan operation. This cohort also has higher SpO2 levels and lower recent NT-proBNP values.  (2) High recent NT- proBNP and elevated Fontan pressure are critical factsors associated with a worse event-free survival and MACE. The cutoff points of NT-proBNP and Fontan pressure for worse event-free survival are 467.7 pg/mL and 18 mm Hg, respectively. Materials and Methods: Limitation: Single center, retrospective nature of study, non-randomized, observational design limits causal inference despite propensity matching. Variable follow-up including interval measurement of NT-proBNP monitoring and catheterization timing Major adverse cardiovascular events (MACE) were similar regardless of fenestration patency suggesting benefit to a subset of diverse patient population.  Selection bias with a favorable hemodynamic parameter for transcatheter closure group which may impact overall survival benefit.  Conclusion: This large longitudinal study by Lim et al. could be a steppingstone in long term monitoring and utility of fenestration in a subset of Fontan patients. It emphasizes that occluded fenestration spontaneous or via transcatheter has been associated with better long-term survival without increasing Fontan pressure significantly. However, the findings are best interpreted with caution due to the retrospective design and potential unmeasured confounders. The study lays essential groundwork for future prospective trials and reinforces the importance of individualized closure decisions guided by NT-proBNP, Fontan pressures, and pre-closure hemodynamics.