Article : Functional Capacity in Heart Failure...

Functional Capacity in Heart Failure: Which Test, and for What Purpose?

As a prognostic tool, the 6-minute walk test was as good as cardiopulmonary exercise testing, but neither added much to clinical and demographic markers.


Functional capacity is considered to be an important clinical and prognostic measure in patients with heart failure (HF). Cardiopulmonary exercise testing (CPXT) — to determine oxygen consumption (VO2) and ventilatory equivalent–carbon dioxide ratio (VE/VCO2) — is generally recognized as the standard quantitative method for this parameter. The 6-minute walk test (6MWT) is a simpler alternative to CPXT, but it has not been rigorously compared with CPXT regarding its prognostic value.

To assess the utility of these functional measures for predicting mortality and hospitalization, investigators conducted a post-hoc analysis of data from the HF-ACTION trial (JW Cardiol Apr 8 2009) involving 2054 ambulatory patients with systolic HF and moderate symptoms (median age, 59; 29% women; 64% New York Heart Association class II) who underwent both 6MWT and treadmill CPXT according to standardized protocols. In a predictive model that included various other patient characteristics, the C-index for mortality increased from 0.69 to 0.72 with 6MWT distance and to 0.73 with peak VO2 (C-index values range from 0.5 [a coin toss] to 1.0 [perfect discrimination]). Results for a composite of all-cause hospitalization and mortality were qualitatively similar to those for mortality. Adding VE/VCO2 slope to the model did not improve discrimination.

CITATION(S):

Forman DE et al. 6-minute walk test provides prognostic utility comparable to cardiopulmonary exercise testing in ambulatory outpatients with systolic heart failure. J Am Coll Cardiol 2012 Nov 21; [e-pub ahead of print].

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