MELD-XI score is not associated with adverse outcomes in ambulatory adults with a Fontan circulation

Background: The Model for End-stage Liver Disease excluding INR (MELD-XI) is commonly used to identify patients with a Fontan circulation at increased risk of adverse events, However, this approach has not been evaluated in unselected ambulatory adults. Methods: We enrolled a cohort of 163 outpatients with a Fontan circulation aged ≥18-years in the Boston Adult Congenital Heart Disease Biobank from 2012 to 2018. Survival analysis was performed to assess the relationship between MELD-XI with both all-cause mortality and a composite outcome of mortality or non-elective cardiovascular hospitalization. Results: Mean age was 30.2±9.7 years, and 41.1% were women. Most had a lateral tunnel Fontan (62.6%). MELD-XI score averaged 10.6±2.1 (median = 13). Both creatinine and total bilirubin were ≤1.0 mg/dL in 94/163 (57.7%), translating to the lowest possible score. MELD-XI<11 was present in 123 patients (75.5%), while only 3 (1.8%) had MELD-XI>18. During follow-up of 3.2±2.2 years, the composite outcome occurred in 58 patients (35.6%), with 16 deaths (9.8%). Most deaths (n = 11, 68.8%) and composite outcomes (n = 39, 67.2%) occurred among patients with MELD-XI less than the median. MELD-XI score did not differ between those who did and did not have events (death: 10.8±2.2 vs. 10.6±2.1; p = 0.92; composite outcome: 10.6±2.2 vs. 10.7±2.1, p = 0.45). Likewise, survival analysis did not suggest an association between MELD-XI and either outcome. Conclusions: MELD-XI score does not appear to be associated with risk for adverse outcomes in an unselected cohort of outpatients with a Fontan circulation. Prior findings may reflect conditioning on a clinical referral for laboratory testing.