Increased Urinary Liver-Type Fatty Acid–Binding Protein Level Predicts Worsening Renal Function in Patients With Acute Heart Failure

ABSTRACT Background Urinary liver-type fatty acid–binding protein (L-FABP) is a potential biomarker for acute kidney injury, and it in turn increases cardiovascular mortality. We tested whether the urinary L-FABP level predicted short- and mid-term outcomes in patients with acute heart failure. Methods and Results We enrolled consecutive patients with acute heart failure, and measured their urinary L-FABP levels before acute treatment. Worsening renal function (WRF), defined as both an absolute increase in the serum creatinine level of ≥0.3mg/dL and a ≥25% relative increase in its level from baseline, occurred in 37 (26.8%) of 138 patients. Patients with a urinary L-FABP level above the upper normal limit (8.4 µg/g creatinine) (n = 49; 35.5%) were more likely than those with a urinary L-FABP level within normal limits (n = 89; 64.5%) to develop WRF (n = 26 [53.1%] vs n = 11 [12.4%]; P P  = .01). During 1 year of follow-up, 12 patients (8.7%) died, and urinary L-FABP level had no association with all-cause mortality. There was, however, a tendency toward a higher readmission rate in patients with a urinary L-FABP level above the upper normal limit who survived the index hospitalization (n = 46) than in those without an abnormal L-FABP level (n = 88; n = 13 [28.3%] vs n = 13 [14.8%]; log-rank P  = .06). Conclusions Increased urinary L-FABP level before treatment may predict WRF in patients with acute heart failure. Further investigation is warranted for its predictive ability of adverse outcomes.