title: BNP at discharge in acute heart failure patients: is it all about volemia? A study using impedance cardiography to assess fluid and hemodynamic status.
abstract: BACKGROUND
  Besides hemodynamic parameters, several other variables have been associated to B-type natriuretic peptide (BNP) levels. Limited knowledge on BNP determinants in acute heart failure (HF) can undermine the interpretation of BNP levels.
  
  
  RESULTS
  To identify predictors of BNP levels, we evaluated 163 hospitalized acute HF patients. Thoracic fluid content (TFC) and hemodynamic parameters were measured by impedance cardiography at discharge. Patients were followed-up for 60 days for the occurrence of death/hospital admission. Median discharge BNP levels were 659.3 pg/ml. In multivariable linear regression analysis, TFC (β=0.043, 95% CI 0.024-0.062 per U/kΩ, p<0.001) was a powerful predictor of BNP levels, independently of known markers of HF severity like severe systolic dysfunction and discharge New York Heart Association class. Other independent predictors were: new onset HF, albumin, and body mass index. Sex, left cardiac work index, stroke index, hemoglobin, renal failure and discharge furosemide and lisinopril doses were associated to BNP only in univariate analysis. During follow-up, 45 (27.6%) patients were hospitalized or died. TFC (HR=1.047 (1.016-1.080) per U/kΩ increase, p=0.003) and BNP (HR=1.003 (1.001-1.004) per 10 pg/ml increase, p<0.001) were univariate predictors of the outcome, but in multivariate Cox regression analysis, only BNP was independently associated with prognosis.
  
  
  CONCLUSIONS
  Discharge BNP levels in acute HF patients reflected volemia and disease severity. Persistently high BNP levels during hospitalization should raise the possibility of remaining congestion, which could negatively influence prognosis. The utility of BNP as prognostic marker in HF may reside on its ability to reflect multiple underlying pathophysiological disturbances.
authors.affiliation: Department of Internal Medicine, Hospital S. João, Porto, Portugal; Unit of Cardiovascular Research & Development, University of Porto Medical School, Porto, Portugal. Electronic address: joanamartinspimenta@gmail.com.
authors.forename: Joana
authors.initials: J
authors.lastname: Pimenta
authors.affiliation: Department of Internal Medicine, Hospital S. João, Porto, Portugal; Unit of Cardiovascular Research & Development, University of Porto Medical School, Porto, Portugal.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Paulo
authors.affiliation: Department of Internal Medicine, Hospital S. João, Porto, Portugal; Unit of Cardiovascular Research & Development, University of Porto Medical School, Porto, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Mascarenhas
authors.affiliation: Department of Internal Medicine, Hospital S. João, Porto, Portugal.
authors.forename: André
authors.initials: A
authors.lastname: Gomes
authors.affiliation: Department of Internal Medicine, Hospital S. João, Porto, Portugal; Unit of Cardiovascular Research & Development, University of Porto Medical School, Porto, Portugal; Department of Hygiene and Epidemiology, University of Porto Medical School, Porto, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Azevedo
authors.affiliation: Department of Cardiology, Hospital S. João, Porto, Portugal; Unit of Cardiovascular Research & Development, University of Porto Medical School, Porto, Portugal.
authors.forename: Francisco
authors.initials: F
authors.lastname: Rocha-Gonçalves
authors.affiliation: Department of Internal Medicine, Hospital S. João, Porto, Portugal; Unit of Cardiovascular Research & Development, University of Porto Medical School, Porto, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Bettencourt
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001811:Blood Volume Determination / Q000379:methods; D001826:Body Fluids / Q000502:physiology*; D002307:Cardiography, Impedance / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood* / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010351:Patient Discharge / Q000639:trends*
chemical_list: D015415:Biomarkers; D020097:Natriuretic Peptide, Brain