GDF-15 levels were elevated in HFpEF patients compared to control groups across all studies analysed, with the exception of a study by Oyama et al. (2023) that compared the HFpEF group with a control group of individuals with atrial fibrillation (AF) and no HF (median GDF-15: 1,599.0 vs. 1,674.0 pg/mL). Here, GDF15 is linked to hydrops fetalis.