Survival by Heart Failure Phenotype in a Fontan Surveillance Population, 2010-2023

Background: The Fontan operation palliates single-ventricle defects but is associated with late morbidity, heart failure (HF), and premature mortality. Long-term survival among Fontan patients by HF phenotype and transplant status are evaluated. Methods: We identified 722 Fontan patients (median age 10.2 years at first encounter; 57.3% male; 41.1% Black) with healthcare encounters between 2010–2023. The cohort was linked to death certificates. HF was categorized by ICD codes as systolic (SHF) or non-systolic (NSHF). Transplant evaluation and procedures were validated by chart review. The first HF-coded encounter, transplant evaluation and transplant date were recorded. Survival was analyzed using Kaplan-Meier methods. Results: Patients without HF were younger [median 6.3 years (5.0–56.0)] than those with NSHF [21.1 years (5.0–44.7)], SHF [16.1 years (5.0–53.0)], transplant [17.3 years (5.3–47.3)], or evaluation without transplant [18.0 years (5.4–50.2)]. Fifty-seven patients died (7.9%, median age 24.6 years). Mortality occurred in 2.8% (no HF), 6.4% (NSHF), 14.0% (SHF), 28.6% (evaluated, not transplanted), and 30.6% (transplanted; p  < 0.001). Post-transplant 1-, 5-, and 10-year survival was 91.7%, 74.4%, and 61.8%, compared to 96.2%, 91.9%, and 77.2% for SHF. NSHF and no HF groups had similar 5-year survival (97.3%). Among 28 patients evaluated but not transplanted, 1-year mortality was 26.6%. Conclusion: The SHF Fontan phenotype was associated with significantly worse survival than Fontan patients without SHF, who have favorable long-term outcomes. Although transplant offers potential benefit, long-term post-transplant survival remains limited. Improved risk stratification to guide optimal transplant timing is essential for this high-risk population.