BackgroundHeart failure (HF) is a global health concern, and oxidative stress has been implicated in its progression. The redox state of human serum albumin, a systemic oxidative biomarker, holds promise as a prognostic marker in HF. This study aimed to investigate the association between the fraction of human mercaptalbumin (fHMA), an indicator of human serum albumin's redox state, and adverse events in HF within a prospective single-hospital-based cohort. MethodsWe enrolled patients hospitalized for HF and measured fHMA using high-performance liquid chromatography at discharge. The primary endpoint was the composite of HF rehospitalization and all-cause death within one year after discharge. ResultsA total of 221 participants (median age:79 years; 35 % female) were included in the study. Over the course of one year, 26.1 % of the patients experienced HF readmission, while 13.1 % died. The low fHMA group divided by median of fHMA (<57.6 %) showed higher composite outcome rates (41.4 % for the low fHMA vs. 24.6 % for the high fHMA, p = 0.0114). Multivariate analysis, accounting for seven potential confounders, identified low fHMA (adjusted HR: 1.79 [1.03–3.11]) and lower hemoglobin as independent predictors of HF prognosis. ConclusionsThe findings in this study provide the first evidence that fHMA is a potential novel prognostic biomarker in patients with HF.