title: Assessment of Functional Capacity in Chagas Heart Disease by Incremental Shuttle Walk Test and its Relation to Quality-of-Life.
abstract: BACKGROUND
  The cardiopulmonary exercise test (CPET) is considered to be the gold standard to evaluate functional capacity (FC) in patients with heart failure. However, field tests such as the 6-min walk test (6MWT) and the incremental shuttle walk test (ISWT) are simple and effective in evaluating the same. Despite the increasing use of ISWT, no studies that used the test in patients with Chagas heart disease (CHD) were found and only few studies have evaluated the health-related quality-of-life (HRQoL) in this population. The objective of this study was to correlate the distance walked in the ISWT with distance walked by 6MWT and peak oxygen uptake (VO2peak) by CPET and HRQoL in patients with CHD.
  
  
  METHODS
  A total of 35 patients with CHD were evaluated according to the FC and HRQoL. The FC was assessed by CPET, 6MWT and ISWT. HRQoL was assessed by the generic short-form health survey (SF-36) and Minnesota Living with Heart Failure Questionnaire (MLHFQ). Descriptive data were shown as mean and standard deviation or median and interquartile range. The correlation was carried out with Pearson or Spearman correlation test. A receiver operating characteristic (ROC) curve was constructed to investigate the accuracy of ISWT for predicting low values of VO2peak.
  
  
  RESULTS
  The distance walked in ISWT correlated with VO2peak(r = 0.587; P < 0.001), distance walked in 6MWT (r = 0.484; P = 0.003), MLWHFQ scores (r = -0.460; P = 0.006) and physical functioning and role physical domains of the SF-36 scores (r = 0.435, P = 0.009; r = 0.477, P = 0.008, respectively). There was no significant difference between the distances walked in field tests (P = 0.694). The area under the ROC curve was 0.871 for ISWT in predicts a VO2peak value of, at least, 25 mL/kg/min.
  
  
  CONCLUSIONS
  The ISWT showed to be effective in evaluating the FC in CHD and in demonstrate the impact of disease on some aspects of the HRQoL of these patients.
authors.affiliation: School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Henrique Silveira
authors.initials: HS
authors.lastname: Costa
authors.affiliation: School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Rafael Leite
authors.initials: RL
authors.lastname: Alves
authors.affiliation: School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Stela Alves
authors.initials: SA
authors.lastname: da Silva
authors.affiliation: School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Maria Clara Noman
authors.initials: MC
authors.lastname: Alencar
authors.affiliation: School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Maria do Carmo Pereira
authors.initials: Mdo C
authors.lastname: Nunes
authors.affiliation: Federal University of Jequitinhonha and Mucuri Valleys, Diamantina, Minas Gerais, Brazil.
authors.forename: Márcia Maria Oliveria
authors.initials: MM
authors.lastname: Lima
authors.affiliation: School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Manoel Otávio da Costa
authors.initials: MO
authors.lastname: Rocha
keywords: 6-min walk test; cardiopulmonary exercise test; chagas heart disease; functional capacity; health-related quality-of-life; incremental shuttle walk test