title: Peak oxygen uptake during the incremental shuttle walk test in a predominantly female population with Chagas heart disease.
abstract: BACKGROUND
  Chagas heart disease (CHD) patients may have a reduced functional capacity (FC). Field tests, as the Incremental Shuttle Walk Test (ISWT), can estimate peak oxygen uptake (VO2 peak). However, the relationship between the ISWT and the Cardiopulmonary Exercise Testing (CPET), the gold standard in the assessment of FC, is not well established in CHD patients.
  
  
  OBJECTIVE
  This study aimed to evaluate the FC of CHD patients by ISWT with direct measurement of VO2 peak and to compare these findings with data obtained from CPET. A secondary goal was to derive a regression equation to calculate the VO2 peak by ISWT.
  
  
  METHODS
  Cross-sectional and correlative study.
  
  
  METHODS
  Research laboratory setting.
  
  
  METHODS
  Thirty-two CHD patients (58.8±9.0 years, 81.3% women) participated in this study.
  
  
  METHODS
  Eligible patients underwent clinical evaluation, echocardiography, CPET by ramp protocol and ISWT according to current guidelines.
  
  
  RESULTS
  The distance walked in ISWT showed a positive correlation with VO2 peak from CPET and ISWT (r=0.456, P=0.009 and r=0.869, P<0.001, respectively). In the agreement analysis, the values of the differences between VO2 peak from CPET and ISWT showed absence of bias (mean bias ±95% CI and mean -1.29±5.09 mL.kg.min). Based in real values of VO2 obtained from ISWT, one equation including sex, functional class and distance walked was provided to predict the VO2 values in this test.
  
  
  CONCLUSIONS
  This study showed the good correlation between distance walked in ISWT and VO2 peak directly measured in both tests, and additionally, provided an equation to calculate a predictive VO2 peak by ISWT, suggesting a good alternative to evaluate the FC of CHD patients, especially in locations where sophisticated testing is not available.
  
  
  CONCLUSIONS
  The results confirm the possibility of using the ISWT for the evaluation of the FC in patients with CHD, especially in locations where sophisticated testing is not available.
authors.affiliation: Department of Internal Medicine Medical School and Hospital das Clinicas of the Federal University of Minas Gerais (UFMG) Belo Horizonte, Brazil - marcialima_ufvjm@yahoo.com.br.
authors.forename: Rafael
authors.initials: R
authors.lastname: Alves
authors.forename: Marcia M
authors.initials: MM
authors.lastname: Lima
authors.forename: Cheyenne
authors.initials: C
authors.lastname: Fonseca
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Dos Reis
authors.forename: Pedro H
authors.initials: PH
authors.lastname: Figueiredo
authors.forename: Henrique
authors.initials: H
authors.lastname: Costa
authors.forename: Lucas
authors.initials: L
authors.lastname: Kreuser
authors.forename: Maria C
authors.initials: MC
authors.lastname: Nunes
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Ribeiro
mesh_terms: D000368:Aged; D002598:Chagas Cardiomyopathy / Q000378:metabolism* / Q000503:physiopathology* / Q000534:rehabilitation; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012737:Sex Factors; D000070857:Walk Test; D016138:Walking / Q000502:physiology*