Recent randomized controlled trials (RCTs) and meta-analyses of RCTs reported that sodium–glucose cotransporter 2 (SGLT-2) inhibitors improved cardiovascular outcomes in patients with HF with reduced EF (HFrEF).[13–16] Although the effects of SGLT-2 inhibitors in HFpEF patients have been examined in multiple RCTs,[17–21] the results are inconsistent due partly to limited power. This evidence concerns the gene SLC5A2 and hydrops fetalis.