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. 2021 May;116(5):889-895.
doi: 10.36660/abc.20190624.

The Six-Minute Step Test as a Predictor of Functional Capacity according to Peak VO2 in Cardiac Patients

[Article in English, Portuguese]
Luiz Eduardo Fonteles Ritt  1   2 , Eduardo Sahade Darzé  1   2 , Gustavo Freitas Feitosa  1 , Jessica Santana Porto  1 , Gabriela Bastos  1 , Renata Braga Linhares de Albuquerque  2 , Cristiane Miura Feitosa  1 , Thaissa Costa Claro  1 , Eloisa Ferreira Prado  1 , Queila Borges de Oliveira  1 , Ricardo Stein  3   4
Affiliations

The Six-Minute Step Test as a Predictor of Functional Capacity according to Peak VO2 in Cardiac Patients

[Article in English, Portuguese]
Luiz Eduardo Fonteles Ritt et al. Arq Bras Cardiol. 2021 May.

Abstract
in English, Portuguese

Background: Six-minute step test (6MST) is a simple way to evaluate functional capacity, although it has not been well studied in patients with coronary artery disease (CAD) or heart failure (HF).

Objective: Analyze the association between the 6MST and peak oxygen uptake (VO2peak) and develop an equation for estimating VO2peak based on the 6MST, as well as to determine a cutoff point for the 6MST that predicts a VO2peak ≥20 mL.Kg-1.min-1.

Methods: In 171 patients who underwent the 6MST and a cardiopulmonary exercise test, correlation, regression, and ROC analysis were used and a p < 0.05 was admitted as significant.

Results: mean age was 60±14 years and 74% were male. Mean left ventricle ejection fraction was 57±16%, 74% had CAD and 28% had HF. Mean VO2peak was 19±6 mL.Kg-1.min-1 and mean 6MST performance was 87±45 steps. Association between 6MST and VO2peak was r 0.69 (p <0.001). The model VO2peak =19.6 + (0.075 x 6MST) - (0.10 x age) for men and VO2peak =19.6 + (0.075 x 6MST) - (0.10 x age) - 2 for women could predict VO2peak based on 6MST results (adjusted R 0.72; adjusted R2 0.53). The most accurate cutoff point for 6MST to predict a VO2peak ≥20 mL.Kg-1.min-1 was >105 steps (AUC 0.85; 95% CI 0.79 -0.90; p <0.001).

Conclusion: An equation for predicting VO2peak based on 6MST results was derived, and a significant association was found between 6MST and VO2peak. The cutoff point for 6MST, which predicts a VO2peak ≥20 mL.Kg-1.min-1, was >105 steps. (Arq Bras Cardiol. 2021; 116(5):889-895).

Fundamento: O teste do degrau de seis minutos (TD6) é uma forma simples de avaliar a capacidade funcional, embora tenha sido pouco estudado em pacientes com doença arterial coronariana (DAC) ou insuficiência cardíaca (IC).

Objetivo: Analisar a associação entre o TD6 e o consumo de oxigênio de pico (VO2pico) e desenvolver uma equação que estime o VO2pico com base no TD6, bem como determinar um ponto de corte para o TD6 que preveja um VO2pico ≥ 20 mL.kg-1.min-1.

Métodos: Nos 171 pacientes submetidos ao TD6 e a um teste de exercício cardiopulmonar, análises da curva ROC, de regressão e de correlação foram usadas, e um p < 0,05 foi admitido como significativo.

Resultados: A idade média foi 60±14 anos, e 74% eram do sexo masculino. A média da fração de ejeção ventricular esquerda foi 57±16%; 74% apresentavam DAC, e 28%, IC. A média do VO2pico foi 19±6 mL.kg-1.min-1, e o desempenho médio do TD6 foi 87±45 passos. A associação entre o TD6 e o VO2pico foi r 0,69 (p < 0,001). Os modelos VO2pico = 19,6 + (0,075 x TD6) – (0,10 x idade) para homens e VO2pico = 19,6 + (0,075 x TD6) – (0,10 x idade) – 2 para mulheres poderiam prever o VO2pico com base nos resultados do TD6 (R ajustado 0,72; R2 ajustado 0,53). O ponto de corte mais acurado para que o TD6 preveja um VO2pico ≥ 20 mL.kg-1.min-1 foi de > 105 passos [área sob a curva 0,85; intervalo de confiança de 95% 0,79 - 0,90; p < 0,001].

Conclusão: Uma equação que preveja o VO2pico com base nos resultados do TD6 foi derivada, e foi encontrada uma associação significativa entre o TD6 e o VO2pico. O ponto de corte do TD6, que prevê um VO2pico ≥ 20 mL.kg-1.min-1, foi > 105 passos. (Arq Bras Cardiol. 2021; 116(5):889-895).

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Conflict of interest statement

Potencial Conflito de Interesses

Declaro não haver conflito de interesses pertinentes.

Figures

Figura 1
Figura 1. Associação entre o TD6 e o VO2pico.
Figura 2
Figura 2. Gráfico de Bland-Altman para VO2pico previsto vs. Determinado.
Figura 3
Figura 3. Curva ROC para que o TD6 preveja um VO2pico≥ 20 mL.kg1-.min-1. Área sob a curva 0.85 (IC95% 0,79 – 0,90) p < 0,001.
Figure 1
Figure 1. Association between 6MST and VO2peak.
Figure 2
Figure 2. Bland-Altman plot for predicted versus determined VO2peak.
Figure 3
Figure 3. ROC curve for 6MST to predict a VO2peak ≥ 20 mL.Kg1-.min-1 AUC 0.85 (95% CI 0.79 – 0.90) p < 0.001.
See this image and copyright information in PMC

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