Relationship between Six-Minute Walk Test and Left Ventricular Systolic Function in Nigerian Patients with Heart...

Heart failure (HF) is a major public health problem. The six-minute walk test (6MWT) is a submaximal exercise test performed even by HF patients not tolerating maximal exercise testing. The left ventricular ejection fraction is one of the strongest indicators of mortality in HF. Literature reports that relationship between 6MWT and (Left Ventricular Systolic Function (LVSF) were not homogenous, hence the need for this study.

One hundred and forty consenting HF patients in NYHA II and III were consecutively recruited after obtaining ethical clearance. The patients were made to walk on a level ground at their own convenient pace while attempting to cover as much ground as possible in six minutes. Echocardiography was also performed on all the patients.

Eighty-five (60.7%) were women. The population mean age was 48.2 ± 14.5 years. The average distance walked was 272.2 ± 114.0 meters and the mean ejection fraction (EF) was 36.73 ± 15.04. Patients in NYHA II significantly walked longer than those in NYHA III (334.81 ± 98.80m vs 204.05 ± 87.66m; p<0.001). There was no correlation between the distance walked and LVSF; EF(r = -0.402, P = 0.534), SF (r = -0.128, P = 0.878).The independent predictors of distance walked were sex (p=0.021) and NYHA stage(p<0.0001).

NYHA stage and sex independently predicted the distance walked in our HF patients. There was an inverse relationship between 6MWT and NYHA, with no correlation between 6MWT and LVSF. 6MWT therefore, appears not to be a good measure of LVSF as assessed by M-mode derived EF, in our HF patients.