Key result
Six-minute walk test matches cardiopulmonary exercise testing for predicting adverse outcomes in systolic heart failure.
Why the study?
CPX and 6MW tests are commonly used prognostic gauges in systolic HF, but few direct comparisons have been conducted.
Does the 6-minute walk test provide comparable prognostic utility to cardiopulmonary exercise testing for predicting mortality and hospitalization in stable outpatients with systolic heart failure?
Cohort (n=2,054)
Blinded clinical endpoint committee
Yes
Does the 6-minute walk test provide comparable prognostic utility to cardiopulmonary exercise testing for predicting mortality and hospitalization in stable outpatients with systolic heart failure?
The 6-minute walk test is a practical, inexpensive alternative to cardiopulmonary exercise testing that provides comparable prognostic information in stable systolic heart failure patients.
Answers are grounded in this paper and cite their sources.
Supports 6MWT as simpler prognostic alternative in systolic HF outpatients; extends prior comparisons but leaves open prospective validation.
Objectives To compare the prognostic efficacy of 6MW and CPX tests in stable outpatients with chronic HF. Background Cardiopulmonary exercise (CPX) and 6 minute walk (6MW) tests are commonly applied as prognostic gauges for systolic heart failure (HF) patients, but few direct comparisons have been conducted. Methods Stable NYHA class II and III systolic HF patients (ejection fraction ≤35%) from Heart Failure: A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION) were studied. 6MW distance (6MWD) and CPX indices (peak oxygen consumption [VO2] and minute ventilation-carbon dioxide production [VE/VCO2] slope) were compared as predictors of all-cause mortality/hospitalization and all-cause mortality over 2.5 years mean follow-up. Results 2,054 HF-ACTION participants underwent both CPX and 6MW tests at baseline (median age 59 years; 71% male; 64% NYHA class II and 36% NYHA class III). In unadjusted models and in models that included key clinical and demographic covariates, C-indices of 6MWD were 0.58 and 0.65 (unadjusted) and 0.62 and 0.72 (adjusted) in predicting all-cause mortality/ hospitalization and all-cause mortality, respectively. C-indices for peak VO2 were 0.61 and 0.68 (unadjusted) and 0.63 and 0.73 (adjusted). C-indices for VE/VCO2 slope were C=0.56 and 0.65 (unadjusted) and 0.61 and 0.71 (adjusted); combining peak VO2 and VE/VCO2 slope did not improve C-indices. Overlapping 95% confidence intervals and modest integrated discrimination improvement values confirmed similar prognostic discrimination by 6MWD and CPX indices within adjusted models. Conclusion In systolic HF outpatients 6MWD and CPX indices demonstrated similar utility as univariate predictors for all-cause hospitalization/mortality and all-cause mortality. However, 6MWD or CPX indices added only modest prognostic discrimination to models that included important demographic and clinical covariates.
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Forman et al. (2012) conducted a cohort in Systolic heart failure (n=2,054). 6-minute walk test (6MWD) vs. Cardiopulmonary exercise testing (CPX) was evaluated on All-cause mortality or hospitalization (C-index 0.62 (adjusted)). In systolic heart failure outpatients, the 6-minute walk test demonstrated similar prognostic utility to cardiopulmonary exercise testing for predicting all-cause hospitalization or mortality.
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