Arq. Bras. Cardiol. 2021; 116(5): 889-895

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

Luiz Eduardo Fonteles Ritt , Eduardo Sahade Darzé, Gustavo Freitas Feitosa, Jessica Santana Porto, Gabriela Bastos, Renata Braga Linhares de Albuquerque, Cristiane Miura Feitosa, Thaissa Costa Claro, Eloisa Ferreira Prado, Queila Borges de Oliveira, Ricardo Stein

DOI: 10.36660/abc.20190624

This Original Article is referred by the Short Editorial "The Six-Minute Step Test as an Alternative for Functional Capacity Assessment in Patients with Cardiovascular Diseases".

Abstract

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 (VO_2peak) and develop an equation for estimating VO_2peak based on the 6MST, as well as to determine a cutoff point for the 6MST that predicts a VO_2peak ≥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 VO_2peak was 19±6 mL.Kg^-1.min^-1 and mean 6MST performance was 87±45 steps. Association between 6MST and VO_2peak was r 0.69 (p <0.001). The model VO_2peak =19.6 + (0.075 x 6MST) – (0.10 x age) for men and VO_2peak =19.6 + (0.075 x 6MST) – (0.10 x age) – 2 for women could predict VO_2peak based on 6MST results (adjusted R 0.72; adjusted R² 0.53). The most accurate cutoff point for 6MST to predict a VO_2peak ≥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 VO_2peak based on 6MST results was derived, and a significant association was found between 6MST and VO_2peak. The cutoff point for 6MST, which predicts a VO_2peak ≥20 mL.Kg^-1.min^-1, was >105 steps. (Arq Bras Cardiol. 2021; 116(5):889-895)