Fontan palliation allows many single-ventricle patients to reach adulthood, but it does not correct the underlying physiology. Their circulation, destined for eventual failure, depends on a delicate balance between systemic venous pressure and pulmonary vascular resistance. Over time, these patients develop complications of chronic venous congestion—hepatic dysfunction, protein-losing enteropathy, and lymphatic disorders—resulting in multiorgan fragility that ultimately necessitates transplant evaluation.
The decision to proceed with heart transplantation, however, remains complex. Not all comorbidities carry equal prognostic weight, and previous studies have provided fragmented data. This work offers an integrated analysis by Fontan-specific morbidities and time phases, addressing a crucial surgical question: what are the warning signs we should recognize to avoid late referral for transplantation?
The study analyzed a retrospective cohort of 409 Fontan patients listed for heart transplantation between 2008–2022. Collected variables included demographic data, medical and surgical history, and clinical parameters during the waiting period. A set of predefined Fontan morbidities was established using operational criteria:
– Cyanosis (resting SatO₂ <90%)
– Obstruction of the Fontan pathway or pulmonary artery
– Patent fenestration
– Polycythemia
– Liver disease
– HLA sensitization
– Hospitalizations during the previous year
The analysis compared survivors and non-survivors at three points: while on the waiting list, within one year post-transplant, and across the entire interval from listing to one year post-transplant. The primary endpoint was death during this combined period. Independent predictors were identified through multivariable logistic regression.
During the waiting period, 5.9% of patients died; 83.4% underwent transplantation, and 8.5% of those died within the first postoperative year, yielding an overall 1-year survival of approximately 92%. The most vulnerable phase—between listing and early postoperative recovery—accounted for a substantial proportion of events.
Univariate analysis showed that waitlist mortality was associated with higher aortopulmonary collateral burden, more than one hospitalization in the prior 12 months, younger age, worse NYHA class, lack of school or employment, single-parent household, and sleep apnea.
In contrast, one-year post-transplant mortality correlated with patent fenestration, Fontan pathway or pulmonary artery obstruction, clinical cyanosis, polycythemia, portal varices, and a mental health disorder under treatment.
In the multivariable model for the combined outcome (death between listing and 1 year post-transplant), two independent predictors emerged: more than one hospitalization in the prior year (OR = 2.0; p = .05) and resting cyanosis (OR = 5.0; p= .002).
Therefore, the authors conclude that mortality during this interval remains clinically relevant. Cyanosis is a strong marker of reduced survival, and repeated hospitalizations should accelerate referral and decision-making.
COMMENTARY:
For the surgeon, the practical translation is straightforward. Two red flags—persistent cyanosis and recurrent hospitalizations—are not background noise; they mean the clock is running against the patient. Cyanosis, often signaling active collaterals, an open fenestration, or pathway obstruction, also reflects a more unfavorable systemic condition (coagulopathy, deconditioning, organ dysfunction) that transplantation does not immediately reverse. Hence, pretransplant optimization should include a clear roadmap: selective embolization of aortopulmonary collaterals when indicated, assessment of fenestration patency, and correction of stenoses or obstructions within the circuit.
Recurrent hospitalization reflects clinical instability caused by infections, hemodynamic decompensation, nutritional or lymphatic issues, and frequently psychosocial barriers to adherence. This pattern defines frailty. When the interval between admissions shortens, the window for optimizing the candidate narrows. This is not a statistical nuance—it is a call to activate pathways and prioritize listing.
Some limitations must be acknowledged when interpreting the results: the retrospective design, the low absolute number of events (particularly during the waiting phase), potential center bias due to high-experience programs, and the absence of data on non-listed Fontan patients. These do not invalidate the message but emphasize that the findings represent consistent trends rather than absolute rules for every case.
A simple, shared routine can be derived for congenital and transplant teams alike: measure and record resting oxygen saturation at each visit, treating it as a fifth vital sign. If saturation persistently falls below 90%, referral to advanced heart failure evaluation should be considered. In parallel, tracking the number of hospitalizations over the preceding 12 months is essential; two or more should raise the priority level and accelerate assessment.
REFERENCE:
Schumacher KR, Rosenthal DN, Batazzi A, Yu S, Reichle G, Bano M. The Impact of Fontan Circulatory Failure on Heart Transplant Survival: A 20-Center Retrospective Cohort Study. Circulation. 2025 Aug 26;152(8):508-518. doi: 10.1161/CIRCULATIONAHA.124.072961. Epub 2025 Jul 9. PMID: 40631708.
