Background: Characteristics of heart failure with recovered ejection fraction (HFrecEF) have not yet been fully understood. The objective of this study is to identify potential biomarkers for the left ventricular ejection fraction(LVEF) recovery. Methods: Antibody microarrays were used to detect proteins in serum of healthy volunteers, patients with heart failure with reduced ejection fraction(HFrEF), and patients with HFrecEF, looking for specific proteins of HFrecEF patients.Results:1000

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... ins were detected in the sera of healthy volunteers, HFrEF patients and HFrecEF patients using antibody microarrays (three in each group). There were dozens of different proteins between each group. Based on the signal strength, fold changes, clinical significance and Venn diagram analysis, 11 proteins were selected to be detected in the sera of 10 healthy volunteers ,47 HFrEF patients and 22 HFrecEF patients using antibody microarrays. Serum concentrations of cysteine dioxygenase type 1 (CDO1) and growth/differentiation factor 8 (GDF-8) were significantly downregulated in HFrecEF patients compared with HFrEF patients. ROC curve analysis showed that the area under the CDO1 curve was 0.662(95%CI 0.517-0.808,P=0.031).The sensitivity of CDO1 was 77%, the specificity was 54%, and diagnostic cut‑off points was 10198.5.The GDF-8 has no diagnostic value. Kaplan–Meier survival curves showed that the prognosis is better in HFrecEF patients than HFrEF patients about all cause death(P=0.011) and cardiovascular death(P=0.004).But we did not find that patients with low baseline CDO1 levels (<10198.5) had better outcomes than those with high CDO1 levels (≥10198.5).Conclusions: This pilot study indicates that CDO1 is a potential biomarker of LVEF recovery, which needs to be confirmed by further studies.