Reproducibility of the self-controlled six-minute walking test in heart failure patients.
BACKGROUND
The six-minute walk test (6WT) has been proposed to be a submaximal test, but could actually demand a high level of exercise intensity from the patient, expressed by a respiratory quotient >1.0, following the guideline recommendations. Standardizing the 6WT using the Borg scale was proposed to make sure that all patients undergo a submaximal walking test.


OBJECTIVE
To test the reproducibility of the six-minute treadmill cardiopulmonary walk test (6CWT) using the Borg scale and to make sure that all patients undergo a submaximal test.


METHODS
Twenty-three male heart failure patients (50+/-9 years) were included; these patients had both ischemic (5) and non-ischemic (18) heart failure with a left ventricle ejection fraction of 23+/-7%, were diagnosed as functional class NYHA II-III and were undergoing optimized drug therapy. Patients were guided to walk at a pace between "relatively easy and slightly tiring" (11 and 13 on Borg scale). The 6CWT using the Borg scale was performed two times on a treadmill with zero inclination and patient control of speed with an interval of 24 hours. During the sixth minute, we analyzed ventilation (VE, L/min), respiratory quotient, Oxygen consumption (VO2, ml/kg/min), VE/VCO2 slope, heart rate (HR, bpm), systolic blood pressure (SBP, mmHg), diastolic (DBP, mmHg) blood pressure and distance.


RESULTS
The intraclass correlation coefficients at the sixth minute were: HR (r i=0.96, p<0.0001), VE (r i=0.84, p<0.0001), SBP (r i=0.72, p=0.001), distance (r i=0.88, p<0.0001), VO2 (r i=0.92, p<0.0001), SlopeVE/VCO2 (r i=0.86, p<0.0001) and RQ<1 (r i=0.6, p=0.004).


CONCLUSIONS
Using the 6CWT with the Borg scale was reproducible, and it seems to be an appropriate method to evaluate the functional capacity of heart failure patients while making sure that they undergo a submaximal walking test.
Guimarães
Guilherme Veiga
GV
Heart Institute, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
Carvalho
Vitor Oliveira
VO
Bocchi
Edimar Alcides
EA
D000704:Analysis of Variance; D001794:Blood Pressure; D016001:Confidence Intervals; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance; D006333:Heart Failure / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012647:Self-Assessment; D013997:Time Factors; D016138:Walking / Q000502:physiology