Combined Assessment Findings of High Spleen Index and Fibrosis-4 Index Correlate With Fibrosis Progression in Fontan-Associated Liver Disease: A Retrospective Study

SI and FIB-4 are noninvasive indicators of liver fibrosis progression in FALD, reflecting different pathophysiological aspects. SI may reflect the circulatory burden that appears relatively early after surgery, whereas FIB-4 reflects fibrosis accumulation due to aging and chronic congestion. A simultaneously elevated SI and FIB-4 may be associated with rapid fibrosis progression. A combined assessment may be useful for risk stratification and longitudinal monitoring. The relatively low threshold of FIB-4 ≥0.682 may be a practical indicator to detect early FALD-specific fibrosis. Simple monitoring combining splenic assessment by ultrasound and FIB-4 calculation from blood tests can help in the early detection and prognostic evaluation of FALD.