Serum blood urea nitrogen and long-term mortality in acute ST-elevation myocardial infarction

Introduction: Renal dysfunction is associated with increased mortality in acute coronary syndromes and other cardiovascular diseases. The prognostic value of kidney dysfunction has been investigated using creatinine-based measures of renal function. Few data are available on the prognostic significance of blood urea nitrogen (BUN), a sensitive marker of hemodynamic alterations and renal perfusion. Methods: The relationship between estimated glomerular filtration rate (eGFR), BUN on admission and changes in BUN during hospital course and long-term mortality was evaluated in 1507 patients with acute ST-elevation myocardial infarction (STEMI). Results: During a median follow-up of 27 months (range, 12 to 44 months), 281 patients (18.6%) died. In multivariable Cox regression models, elevated BUN (>= 25 mg/dL) at admission was an independent predictor of mortality after adjustments for clinical variables and eGFR (adjusted hazard ratio [HR] 1.7; 95% confidence interval [CI] 1.2-2.3, P=0.0015). Similar results were obtained for elevated BUN/creatinine ratio (>= 25) at admission (adjusted HR 2.0; 95% CI 1.4-2.8; P<0.0001). An increase in BUN 50% above admission value occurred in 260 of patients (17.3%) during hospital course, and was associated with increased risk of mortality after adjustments of clinical variables, eGFR and BUN on admission (HR, 1.7 95% CI 1.3-2.2; P<0.0001). Discussion: Elevated BUN and BUN/creatinine ratio on admission are independent predictors of long-term mortality in patients with STEMI. An increase in BUN level during hospital course portends adverse outcome independent of eGFR and BUN on admission. (C) 2007 Elsevier Ireland Ltd. All rights reserved.