Outcome of Patients with Single Ventricles who Initially did not Indicate Fontan Completion After Stage II Palliation

Despite an early-staged Fontan completion strategy, certain patients after bidirectional cavopulmonary shunt (BCPS) could not undergo swift Fontan completion. This study aimed to clarify the clinical course of these patients. Among all infants with univentricular hearts who underwent BCPS between 1998 and 2022, those who could not undergo the Fontan completion at the initial assessment were identified. The reasons, clinical course, and delayed Fontan completion of these patients were evaluated. A total of 491 patients underwent cardiac catheterization for evaluation of Fontan completion at a median age of 1.8 (1.6-2.3) years and 1.4 (1.2-1.9) years after BCPS. Among them, 470 patients underwent subsequent Fontan (Group F), and 21 patients did not (Group C). There were various reasons, including left pulmonary artery stenosis in 14 patients, high pulmonary artery pressure (PAP) in 7, significant atrioventricular valve regurgitation in 6, and systemic ventricular dysfunction in 5. Delayed Fontan completion was performed in 16 patients at a median age of 5.5 (3.7-5.9) years. Survival at 5 years was 90.9% in Group C and 97.2% in Group F (p = .005). A need for additional pulmonary blood flow (APBF) after BCPS (p = .015) and higher PAP at initial assessment (p = .003) were risk factors for delaying Fontan completion. Left pulmonary artery stenosis requiring APBF and high PAP were contraindications to early Fontan completion. Delayed Fontan completion was possible in most patients with acceptable outcomes, suggesting improvement of Fontan candidacy during follow-up.