Pre-discharge evaluation in heart failure-additive predictive value of the 6-minute walking test to clinical scores

Abstract

Background: We aimed to investigate whether the assessment of functional capacity by the 6-minute walking test (6MWT) might improve the predictive ability of 2 validated clinical scores for risk stratification in heart failure (HF). Methods and Results: The Cardiac and Comorbid Conditions HF (3C-HF) and the Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) scores were evaluated in 466 consecutive HF patients who completed a pre-discharge 6MWT. The 12-month event rate was 7.7%. Both the 2 scores and the 6MWT predicted all-cause mortality (all P<0.0001), with a hazard ratio of 2.650 [95%CI 1.879–3.737], 2.754 [95%CI 1.870–4.056] for each one SD increase in the 3C-HF and MAGGIC, respectively, and of 2.080 [95% CI 1.619–2.671] for each one SD decrease in the meters walked. The addition of a 6MWT to both the 3C-HF and MAGGIC scores significantly improved predictive discrimination (c-index 0.793 [95% CI 0.722–0.864] and 0.802 [95% CI 0.733–0.871], respectively) and risk classification (integrated discrimination improvement, IDI 0.052 [95% CI 0.024–0.101] and 0.046 [95% CI 0.020–0.102], respectively). In the intermediate and high risk strata identified on the basis of both the 3C-HF and MAGGIC scores, mortality rates significantly differed according to a distance walked < or ≥376 m. Conclusions: In HF patients, a pre-discharge evaluation combining the 6MWT to clinical scores improves prediction of 12-month mortality.