ALB and heart failure: In addition to 6MWD, variables that were significantly different between the two groups in Table 2 were included in the univariable time-to-event analyses for the primary outcome (Table 4): age, sex, body surface area, history of coronary artery disease, heart failure, hemoglobin, serum albumin, glomerular filtration rate, and plasma B-type natriuretic peptide level.