A diagnostic accuracy study of mitochondrial FMN during hypothermic oxygenated perfusion to guide liver utilization and avoid normothermic assessment

Extended-criteria donation after circulatory death (ECD-DCD) livers require functional assessment to ensure safe utilization. Sequential (dual) hypothermic oxygenated machine perfusion ((D)HOPE) with controlled oxygenated rewarming (COR) followed by normothermic machine perfusion (NMP) enables viability assessment of ECD-DCD grafts while promoting mitochondrial recovery. Previous work has investigated the added value of flavin mononucleotide (FMN) in risk stratification during DHOPE. This diagnostic accuracy study aimed to compare the predictive value of FMN release during DHOPE with bile quality assessment during subsequent COR-NMP in consecutively accepted ECD-DCD livers. FMN concentrations were measured fluorometrically in perfusate samples collected during DHOPE and not used to guide clinical decision on transplantability. Viability assessment after 2.5 hours of NMP served as the reference standard. Associations between FMN levels and graft utilization were evaluated using receiver operating characteristic analyses. A total of 103 ECD-DCD livers were included, of which 67% were transplanted. FMN demonstrated discriminative ability for graft non-utilization based on bile quality assessment, with AUROC of 0.74 (95% CI 0.60-0.86) at 30 minutes, 0.75 (95% CI 0.63-0.85) at 60 minutes, and 0.70 (95% CI 0.56-0.83) at 120 minutes of DHOPE. Exploratory FMN thresholds showed increasing specificity and positive predictive value over time, reaching 0.92 (95% CI 0.83-0.98) and 0.75 (95% CI 0.53-0.94), respectively, at 120 minutes. Transplanted livers had significantly lower FMN concentrations than declined livers at all time points, with Youden-optimal cutoffs of 9.32 ng/mL, 20.97 ng/mL, and 45.53 ng/mL at 30, 60, and 120 minutes, respectively. FMN release during DHOPE is associated with subsequent NMP viability outcomes in ECD-DCD livers. FMN concentrations may help identify viable and non-viable grafts early during DHOPE, potentially avoiding resource-intensive comprehensive viability assessment with COR-NMP.