title: B-type natriuretic peptides for the evaluation of exercise intolerance.
abstract: BACKGROUND
  Cardiopulmonary exercise testing is the method of choice for the differentiation of exercise intolerance. This study sought to assess the utility of B-type natriuretic peptide (BNP) and N-terminal-pro-B-type natriuretic peptide (NT-proBNP) for the identification of a cardiocirculatory exercise limitation.
  
  
  METHODS
  In 162 patients undergoing cardiopulmonary exercise testing, rest and peak exercise BNP and NT-proBNP levels were measured. In 94 patients fulfilling criteria for appropriate effort and sufficient diagnostic certainty, the accuracy of BNP and NT-proBNP for the prediction of a cardiocirculatory limitation, as assessed based on clinical and exercise testing data, was determined.
  
  
  RESULTS
  A cardiocirculatory limitation was identified in 27 (29%) patients. Median (interquartile range) resting BNP [162 (45-415) vs 39 (19-94) vs 24 (15-46) pg/mL; P <.001] and NT-proBNP [506 (129-1167) vs 77 (35-237) vs 34 (19-77) pg/mL; P <.001] were higher in patients with cardiocirculatory as compared with those with pulmonary limitation (n=28) and those without cardiocirculatory or pulmonary limitation (n=39). The area under the receiver operator characteristics curve for BNP and NT-proBNP to identify a cardiocirculatory limitation was 0.79 and 0.84, respectively (P=.15 for comparison of the curves). Sensitivity and specificity of the optimal BNP cutoff of 85 pg/mL were 63% and 84%, respectively. Sensitivity and specificity of the optimal NT-proBNP cutoff of 223 pg/mL were 74% and 85%, respectively. Peak exercise biomarkers were not more accurate than resting levels.
  
  
  CONCLUSIONS
  Among patients referred for cardiopulmonary exercise testing for evaluation of unexplained exercise intolerance, BNP and NT-proBNP were similarly useful to identify those with a cardiocirculatory limitation.
authors.affiliation: Department of Internal Medicine, University Hospital Basel, Switzerland. chmueller@uhbs.ch
authors.forename: Christian
authors.initials: C
authors.lastname: Mueller
authors.forename: Micha T
authors.initials: MT
authors.lastname: Maeder
authors.forename: Andreas
authors.initials: A
authors.lastname: Christ
authors.forename: Tobias
authors.initials: T
authors.lastname: Reichlin
authors.forename: Daniel
authors.initials: D
authors.lastname: Staub
authors.forename: Markus
authors.initials: M
authors.lastname: Noveanu
authors.forename: Tobias
authors.initials: T
authors.lastname: Breidthardt
authors.forename: Mihael
authors.initials: M
authors.lastname: Potocki
authors.forename: Martin H
authors.initials: MH
authors.lastname: Brutsche
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis*; D003937:Diagnosis, Differential; D004417:Dyspnea / Q000097:blood / Q000175:diagnosis; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010101:Oxygen Consumption; D010446:Peptide Fragments / Q000097:blood*
chemical_list: D000319:Adrenergic beta-Antagonists; D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain