The 6-minute walk test does not reliably detect changes in functional capacity of patients awaiting cardiac transplantation

Authors

Craig Cheetham
Roger Taylor
Valerie Burke
Gerry O'Driscoll, University of Notre Dame AustraliaFollow
Daniel J. Green

Publication Details

Cheetham, C., Taylor, R., Burke, V., O’Driscoll, G., Green, D. J. (2005). The 6-minute walk test does not reliably detect changes in functional capacity of patients awaiting cardiac transplantation. Journal of Heart and Lung Transplantation, 24(7), 848-853. doi:10.1016/j.healun.2004.05.012

Abstract

Background: Peak oxygen consumption ((Vo₂peak) is a strong independent predictor of prognosis in patients with severe chronic heart failure (CHF) and is used to guide optimal timing of transplantation. However, its assessment is relatively expensive and time-consuming and requires sophisticated equipment and highly trained personnel. The purpose of this study was to determine whether changes in 6-minute walk test (6WT) distance, a simple, inexpensive potential alternative measure of functional capacity, can predict changes in Vo₂peak in patients with severe CHF.

Methods: Sixteen subjects (ejection fraction 23 ± 2%, Vo₂peak 16.2 ± 1.1 ml kg ⁻¹min⁻¹) underwent repeated 6WT and Vo₂peak assessments that included familiarization and 4 serial measures, 6 weeks apart (baseline and at Weeks 6, 12 and 18). Analysis compared baseline performance with each subsequent testing occasion.

Results: At baseline, mean (± SE) VO₂peak was 16.3 ± 1.1 ml kg⁻¹ min⁻¹ and 6WT distance was 458 ± 21 m. 6WT and V̇o₂peak were strongly correlated at all timepoints (average r = 0.82; all p < 0.05). However, mixed model analysis, assessing the capacity of the changes seen in 6WT to predict changes in V̇o₂peak, showed no statistical significance (F = 0.11; p = 0.74).

Conclusions: The 6WT is commonly used to assess functional capacity in patients with heart failure. This study demonstrates that, despite a strong cross-sectional correlation with Vo₂peak, changes in the 6WT are not a reliable predictor of changes in Vo₂peak within patients. Therefore, the 6WT has limited utility as a serial measure to assess changes in the clinical status of patients with severe heart failure.

Keywords

peer-reviewed