SLC5A2 and hydrops fetalis: RCT: randomized controlled trial; HFrEF: heart failure with reduced ejection fraction; HFpEF: heart failure with preserved ejection fraction; SGLT2i: sodium-glucose cotransporter 2 inhibitor; CV: cardiovascular; LV: left ventricular; EF: ejection fraction; HF: heart failure; NT-proBNP: N-terminal pro-B-type natriuretic peptide; QoL: quality of life; NS: not significant