Subjectivity and Surveillance Gaps in Post-Fontan Assessment and Their Impact on Late Heart Transplant Referral

The Fontan procedure represents the final stage of palliation for patients with single-ventricle congenital heart disease and has enabled survival into adulthood for a growing population of patients. However, the Fontan circulation is inherently nonphysiological, characterized by chronically elevated systemic venous pressure and reduced cardiac output, which predispose patients to progressive circulatory dysfunction and multiorgan complications. Despite increasing recognition of Fontan circulatory failure, referral for heart transplantation frequently occurs late in the disease course, often after irreversible end-organ damage has developed. Several factors contribute to this delay. Surveillance of ventricular function is largely dependent on echocardiography, which is frequently limited by anatomical complexity and interobserver variability, leading to subjective assessment of ventricular performance. In addition, inconsistent use of invasive hemodynamic assessment and variable implementation of multimodality imaging may delay detection of early circulatory deterioration. Equally important, extracardiac complications, including Fontan-associated liver disease and renal dysfunction, are often under-recognized or inadequately monitored, despite their major impact on transplant candidacy and outcomes. This review examines the limitations of current surveillance strategies in Fontan patients and highlights how subjectivity in cardiac assessment and gaps in systemic monitoring may contribute to delayed transplant referral. A more structured, multidisciplinary surveillance approach incorporating objective imaging and systematic end-organ assessment may facilitate earlier recognition of Fontan failure and improve timing of transplant evaluation.