title: The role of NT-proBNP in explaining the variance in anaerobic threshold and VE/VCO(2) slope.
abstract: OBJECTIVE
  We investigated whether anaerobic threshold (AT) and ventilatory efficiency (minute ventilation/carbon dioxide production slope, VE/VCO2 slope), both significantly associated with mortality, can be predicted by questionnaire scores and/or other laboratory measurements.
  
  
  METHODS
  Anaerobic threshold and VE/VCO(2) slope, plasma N-terminal pro-brain natriuretic peptide (NT-proBNP), and the echocardiographic markers left ventricular ejection fraction (LVEF) and left atrial (LA) diameter were measured in 62 patients with heart failure (HF), who also completed the Minnesota Living with Heart Failure Questionnaire (MLHF), and the Specific Activity Questionnaire (SAQ). Linear regression models, adjusting for age and gender, were fitted.
  
  
  RESULTS
  While the etiology of HF, SAQ score, MLHF score, LVEF, LA diameter, and logNT-proBNP were each significantly predictive of both AT and VE/VCO2 slope on stepwise multiple linear regression, only SAQ score (P < .001) and logNT-proBNP (P = .001) were significantly predictive of AT, explaining 56% of the variability (adjusted R(2) = 0.525), while logNT-proBNP (P < .001) and etiology of HF (P = .003) were significantly predictive of VE/VCO(2) slope, explaining 49% of the variability (adjusted R(2) = 0.45). The area under the ROC curve for NT-proBNP to identify patients with a VE/VCO(2) slope greater than 34 and AT less than 11 mL · kg(-1) · min(-1) was 0.797; P < .001 and 0.712; P = .044, respectively. A plasma concentration greater than 429.5 pg/mL (sensitivity: 78%; specificity: 70%) and greater than 674.5 pg/mL (sensitivity: 77.8%; specificity: 65%) identified a VE/VCO(2) slope greater than 34 and AT lower than 11 mL · kg(-1) · min(-1), respectively.
  
  
  CONCLUSIONS
  NT-proBNP is independently related to both AT and VE/VCO(2) slope. Specific Activity Questionnaire score is independently related only to AT and the etiology of HF only to VE/VCO(2) slope.
authors: Division of Cardiac Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. athanleon@hotmail.com
authors: Leonidas V
authors: LV
authors: Athanasopoulos
authors: Athanasios
authors: A
authors: Dritsas
authors: Helen A
authors: HA
authors: Doll
authors: Dennis V
authors: DV
authors: Cokkinos
mesh_terms: D015308:Anaerobic Threshold / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism*; D005260:Female; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020097:Natriuretic Peptide, Brain / Q000502:physiology*; D010446:Peptide Fragments / Q000502:physiology*; D011788:Quality of Life; D012372:ROC Curve; D012119:Respiration; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D002245:Carbon Dioxide