SLC5A2 and hydrops fetalis: According to the evidence of several well-designed randomized controlled trials (RCTs) for patients with HF with reduced ejection fraction (HFrEF), the HF guidelines strongly recommend the use of combination therapy with foundational drugs, such as angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers, β-blockers, mineralocorticoid receptor antagonists, angiotensin-receptor neprilysin inhibitors (ARNIs), and sodium-glucose co-transporter 2 (SGLT2) inhibitors [3, 4].