SLC5A2 and heart failure: SGLT2, sodium-glucose cotransporter-2; SGLT2i, sodium-glucose cotransporter-2 inhibitors; HF, heart failure; HFrEF, heart failure with reduced ejection fraction; T2DM, type 2 diabetes mellitus; LV, left ventricle/left ventricular; QoL, quality of life; CHF, chronic heart failure; LVEF, left ventricular ejection fraction; NT-proBNP, N-terminal pro B-type natriuretic peptide