NPPB and Abnormal renal physiology: Compared with non-SFI patients, those with SFI were older and more often females; had a higher comorbidity burden; more often had been transferred to CR from acute care after a hospitalization for HF; had higher EF, more prevalent and severe renal dysfunction, and higher NT-proBNP levels; and more often had low sodium levels (Supplementary table S1).