Cardiorespiratory requirements and reproducibility of the six-minute walk test in elderly patients with coronary artery disease

Objectives: To measure the cardiorespiratory requirements of the six-minute walk test (6MWT), to compare this demand with the symptom-limited exercise test (SLET) at ventilatory threshold and at maximal level in elderly patients with coronary artery disease (CAD), and to assess the reproducibility of the 6MWT in cardiorespiratory exchanges in those patients. Design: Comparative and reproducibility sample. Setting: Cardiac rehabilitation service. Participants: Twenty-five people with CAD. Interventions: Subjects performed an SLET and a 6MWT. To test 6MWT reproducibility, 9 patients performed 2 repeated 6MWTs. Main Outcome Measures: The 6MWT cardiorespiratory values, measured with a portable gas analyzer, were compared with the SLET data and with the data from the 2 repeated 6MWTs. Results: The 6MWT peak oxygen uptake (Vo(2)peak, 14.27 +/- 2.94mL(.)min(-1.)kg(-1)) and heart rate (94 +/- 14 beats/min) did not differ from the SLET values at ventilatory threshold (Vo(2), 13.4 +/- 2.65mL(.)min(-1.)kg(-1); heart rate, 91 +/- 17 beats/ min), whereas the 6MWT ventilation (V(E)peak, 36.72 +/- 10.03L/ min) was higher than the SLET at ventilatory threshold (V-E, 31.54 +/- 8.93L/min, P < .03). Maximal 6MWT cardiorespiratory data were lower than the SLET maximal values. Cardiorespiratory values did not differ between the 2 repeated 6MWT (Vo(2)peak, 15.33 +/- 3.52mL(.)min(-1.)kg(-1) vs 15.11 +/- 2.65mL(.)min(-1.)kg(-1); V(E)peak, 39.07 +/- 12.33L/min vs 39.07 +/- 12.13L/min; heart rate, 95 21 beats/min vs 89 15 beats/min). Conclusions: The 6MWT cardiorespiratory requirement values did not differ from SLET values at ventilatory threshold except for ventilation, and 6MWT values are reproducible in elderly patients with CAD.