Patients with chronic kidney disease and heart failure (HF) have been shown to be at higher risk for major adverse cardiovascular events and death. Recent studies have demonstrated that blood urea nitrogen (BUN) might serve as a powerful predictor of mortality in acutely decompensated HF. The goal of this study was to determine the impact of BUN on long-term mortality in patients with stage B and C HF. Our retrospective analysis included patients undergoing percutaneous intervention with a calculated left ventricular ejection fraction < or =50%. Patients on dialysis or with technically inadequate left ventriculograms were excluded. Chart review was performed and mortality data were obtained. Our population included 444 patients with a mean ejection fraction of 38 +/- 10%, mean age of 59 +/- 11 years, median BUN of 14 mg/dl, and median glomerular filtration rate (GFR) of 81 ml/min/1.73 m(2); 31% had stage C HF, and 33% died during follow-up. Patients with increased BUN (> or =17 mg/dl) and decreased GFR (< or =69 ml/min/1.73 m(2)) had significantly increased long-term mortality on Kaplan-Meier analysis (8-year mortalities of 57% and 55%, respectively). In patients with stage C HF, mortalities at 8 years were 69% and 73% with abnormal BUN and GFR, respectively. Proportional hazard regression analysis demonstrated that BUN and stage C HF were independently associated with increased mortality, whereas GFR was not. In conclusion, we demonstrated that BUN is strongly associated with mortality in patients with stage B and C HF and may serve as a better biomarker than GFR for prognostication.