title: NT-proBNP values and Weber functional class in patients with chronic heart failure.
abstract: OBJECTIVE
  To assess the correlation between NT-proBNP values and Weber functional class as determined by cardiopulmonary exercise testing (CPET) in patients with chronic heart failure (CHF).
  
  
  METHODS
  We studied 95 patients, 68 male, mean age 50.4 +/- 10.5 years, with CHF due to dilated cardiomyopathy (DCM), 65% of non-ischemic etiology, classified by symptom-limited treadmill CPET (modified Bruce protocol) as follows: 48 Weber class A, 27 class B, 16 class C and 4 class D. NT-proBNP values (pg/ml) were determined after 15 minutes rest immediately prior to CPET. There were no significant differences between the groups in gender, age or percentage of patients taking ACE inhibitors or ARBs and beta-blockers. Left ventricular ejection fraction was higher in class A and B (27.6+/-8.3%) than in class C and D (19.7+/-6.2%, p=0.001). Serum creatinine was lower in class A (0.97+/-0.22 mg/dl) than in classes C or D (1.16+/-0.26, p=0.006).
  
  
  RESULTS
  NT-proBNP was: class A=1325.8+/-1500.3, class B=3473.0+/-2575.3 (p<0.001 vs. class A), class C=6193.1+/-2066.8 (p<0.001 vs. A and B), while in class D it was 11821.8+/-5489.7. There was an overall significant correlation between NT-proBNP and peak oxygen uptake (r=-0.66, p<0.001). On ROC curve analysis, an NT-proBNP value of 1766.5 pg/ml was found to be the best cut-off to discriminate class A vs. non-A (AUC=0.896, p<0.001, 95% CI 0.834 to 0.957, sensitivity=79%, specificity=83%), while a value of 5029.0 was the best discriminator of class B vs. class C or D (AUC=0.865, p<0.001, 95% CI 0.760 to 0.970, sensitivity=82%, specificity=80%).
  
  
  CONCLUSIONS
  In patients with CHF due to DCM, NT-proBNP values correlate with Weber class as determined by CPET, and this study presents discriminative values.
authors.affiliation: Serviço de Cardiologia, Hospital de Santa Marta, Lisboa, Portugal. ritamarinf@gmail.com
authors.forename: Rita
authors.initials: R
authors.lastname: Fernandes
authors.forename: Joana
authors.initials: J
authors.lastname: Feliciano
authors.forename: Rui M
authors.initials: RM
authors.lastname: Soares
authors.forename: Andreia
authors.initials: A
authors.lastname: Mamede
authors.forename: Ruben
authors.initials: R
authors.lastname: Ramos
authors.forename: Sofia
authors.initials: S
authors.lastname: Silva
authors.forename: José
authors.initials: J
authors.lastname: Serra
authors.forename: José Alberto
authors.initials: JA
authors.lastname: Oliveira
authors.forename: João
authors.initials: J
authors.lastname: Abreu
authors.forename: Ana
authors.initials: A
authors.lastname: Abreu
authors.forename: Rui
authors.initials: R
authors.lastname: Ferreira
mesh_terms: D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000145:classification / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D011446:Prospective Studies
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain