Validity and Reliability of the Six-Minute Walking Test Compared to Cardiopulmonary Exercise Test in Individuals with Heart Failure Systematic Review and Meta-Analysis

Background: Reduced cardiorespiratory fitness along with poor exercise tolerance are regarded as potential morbidity and mortality predictors within the heart failure (HF) population. Despite the reliability and accuracy of the gold-standard cardiopulmonary exercise test (CPET) for assessing cardiorespiratory fitness, its complexity and tolerability issues among HF patients mean that the 6 min walk test (6MWT) is a cost-saving and well-tolerated complementary assessment. We aimed to systematically review the validity, reliability, and safety of the 6MWT compared to CPET for patients with HF. Methods: This study is a systematic review and meta-analysis. Embase, Medline, and Scopus were searched from inception to November 2023. We applied Fisher's z-transformation to correlation coefficients and pooled effects under a random-effects model; heterogeneity (I2), leave-one-out sensitivity, and Egger's test were reported. Results: Twenty studies were finally included, involving 5379 HF participants. A significant moderately strong positive correlation was shown between the 6MWT distance and CPET peak oxygen consumption: (r) = 0.62, 95% CI 0.58-0.66; I2 = 56.95%; p < 0.001. The results showed an excellent test-retest reliability, with a pooled intraclass correlation coefficient of 0.93 (95% CI 0.89-0.95; I2 = 92.06%; p < 0.001). A pooled weighted mean difference of 15.5 m (95% CI 10.2-20.8) was found for the learning effect between the first and second 6MWT. Although some patients required rest stops or reported symptoms such as fatigue or dyspnea, no 6MWTs were terminated due to serious adverse events. Conclusions: Compared with CPET, the 6MWT distance demonstrated a moderately strong correlation with peak VO2, excellent test-retest reliability, and a small learning effect. The 6MWT can therefore complement CPET or serve as a pragmatic alternative when CPET is not feasible; it does not replace comprehensive CPET assessment.