Background: Elevated blood urea nitrogen (BUN) observed in patients hospitalized for acute heart failure syndrome (AHFS) may represent increased neurohumoral activation. The purpose of this study was to examine the prognostic impact of BUN changes during hospitalization on the long-term prognosis of AHFS patients.
Methods and results: The Tohoku Acute Heart Failure Registry (n=497) is a multicenter retrospective cohort study enrolling AHFS patients who were admitted in 2007. The 337 survivors (mean age, 76 years; 52% male) were divided into 3 groups according to tertiles of BUN change during hospitalization: Decreased (D-BUN, ΔBUN (BUN level at discharge-BUN level at hospitalization)≤-1.63 mg/dl, n=112); Unchanged (U-BUN, ΔBUN-1.64 to 5.73 mg/dl, n=113); Increased (I-BUN, ΔBUN>5.73 mg/dl, n=112). The D-BUN group had higher prevalence of lowest glomerular filtration rate during hospitalization, whereas the I-BUN group had higher systolic blood pressure. During a median follow-up period of 2.3 years after discharge, the Kaplan-Meier curve showed that D-BUN and I-BUN had worse prognosis compared with U-BUN. Multivariable logistic model showed that all-cause death was more frequent in I-BUN (hazard ratio, 2.94; 95% confidence interval, 1.51-5.73; P<0.001). Subgroup analysis revealed that BUN increase during hospitalization was associated with all-cause death, regardless of renal function.
Conclusions: AHFS patients with a BUN increase during hospitalization have worse long-term prognosis, independent of renal function.