Comparison between the 6-minute walking test (6MWT) and gait speed (GS) during outpatient cardiac rehabilitation

Abstract

Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): USL TOSCANA CENTRO USL TOSCANA NORD-OVEST Background 6MWT is the gold standard for the functional and prognostic evaluation of patients (P) undergoing cardiac rehabilitation (CR), documenting the increase in exercise capacity induced by CR intervention. However, 6MWT requires an adequate space of at least 30 meters and a non-negligible operator time. GS has been proposed as a test of rapid execution, that can be performed even in a small space. Due to the limited experiences, the aim of the present study was to validate GS in CR in comparison with 6MWT. Material and Methods 44 P (31 males and 13 females; age 68.2 ± 11.9 years) were enrolled consecutively in an outpatient rehabilitation program; 20 of them after cardiac surgery, 18 after acute cardiac syndrome and 6 with heart failure. After evaluating equilibrium and gait with the Tinetti scale (score ≥ 19), P performed 6MWT and GS at the beginning and at the end of the CR program. The speed at GS was calculated as the average of 3 tests. Data were expressed as mean ± SD. The results of 6MWT and GS at the initial and the final evaluation were compared with Student’s t-test for paired data (statistical significance at p <0.05). The Pearson correlation index (r) was calculated to evaluate the linearity relationship between distance traveled at 6MWT and velocity at GS; the statistical significance was tested with ANOVA. The Statistical Package SPSS (version 24) was used for statistical analysis. Results the meters traveled at the initial and the final 6MWT were 434 ± 100 and 491 ± 96 respectively (p <0.001). The velocity in m/sec at the initial and the final GS was 1.68 ± 0.42 and 1.80 ± 0.44 respectively (p <0.001). The correlation between meters traveled and velocity is strong at baseline (r = 0.896) and after CR (r = 0.859), with p <0.001 in both cases. Conclusions certainly, aerobic capacity and resistance to exercise are better described by 6MWT. However, given the strong correlation between the distance traveled at 6MWT and the speed at GS, the latter test can be proposed as a tool for a rapid, precise and repeatable functional evaluation, even in clinical settings other than CR.