Incremental shuttle and six-minute walking tests in the assessment of functional capacity in chronic heart failure.

BACKGROUND: The incremental shuttle test presents some theoretical advantages over the six-minute walk test in chronic heart failure (CHF), including better standardization and less dependency on collaboration.

OBJECTIVES: The present study evaluated test-retest repeatability, test accuracy in predicting a peak oxygen consumption (VO(2)) of 14 mL/kg/min or less, as well as the prognostic value of both walking tests in stable CHF patients.

METHODS: Sixty-three patients (44 men; New York Heart Association functional class II to IV) underwent an incremental treadmill exercise test and, on another day, the walk test in duplicate.

RESULTS: Patients showed well-preserved functional capacity according to the distance walked in both tests (six-minute walk test 491+/-94 m versus incremental shuttle walk test 422+/-119 m; P<0.001). Interestingly, the six-minute and incremental shuttle walk test differences in distance walked were higher in more disabled patients. The mean bias +/-95% CI of the within-test differences were similar (7+/-40 m and 8+/-45 m, respectively). Peak VO(2), but not distance walked in either test, was associated with survival (P<0.05).

CONCLUSIONS: The incremental shuttle walk test showed similar repeatability and accuracy in estimating peak VO(2) compared with the six-minute walk test in CHF patients. Direct measurement of peak VO(2), however, remains superior to either walking test in predicting survival--at least in patients with well-preserved functional capacity.