title: Correlation between NT-proBNP values and changes in functional capacity in patients with chronic heart failure.
abstract: OBJECTIVE
  We set out to evaluate whether changes in N-terminal pro-brain natriuretic peptide (proBNP) can predict changes in functional capacity, as determined by cardiopulmonary exercise testing (CPET), in patients with chronic heart failure (CHF) due to dilated cardiomyopathy (DCM).
  
  
  METHODS
  We studied 37 patients with CHF due to DCM, 81% non-ischemic, 28 male, who performed symptom-limited treadmill CPET, with the modified Bruce protocol, in two consecutive evaluations, with determination of proBNP after 10 minutes rest prior to CPET. The time between evaluations was 9.6+/-5.5 months, and age at first evaluation was 41.1+/-13.9 years (21 to 67). RESULTS IN THE FIRST AND SECOND EVALUATIONS RESPECTIVELY WERE: NYHA functional class >II 51% and 16% (p<0.001), sinus rhythm 89% and 86.5% (NS), left ventricular ejection fraction 24.9+/-8.9% and 26.6+/-8.6% (NS), creatinine 1.03+/-0.25 and 1.09+/-0.42 mg/dl (NS), taking ACE inhibitors or ARBs 94.5% and 100% (NS), beta-blockers 73% and 97.3% (p<0.001), and spironolactone 89% and 89% (NS). We analyzed the absolute and percentage variation (AV and PV) in peak oxygen uptake (pVO2--ml/kg/min) and proBNP (pg/ml) between the two evaluations.
  
  
  RESULTS
  (1) pVO2 AV: -17.4 to 15.2 (1.9+/-5.7); pVO2 PV: -56.1 to 84% (11.0+/-25.2); proBNP AV: -12850 to 5983 (-778.4+/-3332.5); proBNP PV: -99.0 to 379.5% (-8.8+/-86.3); (2) The correlations obtained--r value and p value [r (p)]--are shown in the table below; (3) We considered that a coefficient of variation of pVO2 PV of >10% represented a significant change in functional capacity. On ROC curve analysis, a proBNP PV value of 28% showed 80% sensitivity and 79% specificity for pVO2 PV of >10% (AUC=0.876, p=0.01, 95% CI 0.75 to 0.99).
  
  
  CONCLUSIONS
  In patients with CHF due to DCM, changes in proBNP values correlate with variations in pVO2, as assessed by CPET. However, our results suggest that only a proBNP PV of >28% predicts a significant change in functional capacity.
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: Fernando
authors.initials: F
authors.lastname: Miranda
authors.forename: Sofia
authors.initials: S
authors.lastname: Silva
authors.forename: Ana Teresa
authors.initials: AT
authors.lastname: Timóteo
authors.forename: Ana
authors.initials: A
authors.lastname: Abreu
authors.forename: Rui
authors.initials: R
authors.lastname: Ferreira
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D006333:Heart Failure / Q000097:blood* / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010100:Oxygen / Q000378:metabolism; D010446:Peptide Fragments / Q000097:blood*; D011446:Prospective Studies
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D010100:Oxygen