BACKGROUND/OBJECTIVE: Individuals with chronic heart failure (CHF) suffer from dyspnoea, fatigue and diminished exercise capacity resulting in significant disability. The 6-minute walk test (6MWT), a widely used measure of functional exercise capacity in individuals with cardiovascular, cardiopulmonary and other chronic diseases, is a valuable instrument to assess progression of functional exercise capacity in clinical intervention. Despite the popularity of the 6MWT in clinical settings, it does not have a wide usage in Nigeria. Therefore, this study determined the functional capacity of Nigerians with CHF and compared their cardiorespiratory responses with those of their age-matched apparently healthy individuals.

Methods: This study involved 33 purposively selected individuals with CHF from Lagos University Teaching Hospital (LUTH), Lagos, Nigeria and 36 apparently healthy individuals (AHI). The heart rate (HR), respiratory rate (RR), diastolic blood pressure (DBP), systolic blood pressure (SBP), mean arterial blood pressure (MABP) and pulse pressure (PP) were assessed pre- and post-intervention. Each participant performed the 6MWT on a 30-metre straight-walk course in the medical gymnasium of the hospital. The distance covered in 6-minutes was recorded to the nearest metre. Data were summarized using mean and standard error of the mean. Paired t-tests were used to determine the significance of the differences between pre- and post- intervention scores on all the variables . Independent t-tests were used to determine the significant differences of the variables between the patients with CHF and their AHI. Level of significance was 0.05.

RESULTS

The mean age of the CHF patients group was (male=51.14±1.8yrs, female=47.1±2.9 yrs) while the mean age of the subjects in the AHI group was (male=49±1.5 yrs, female= 48.3 ± 1.6 yrs) respectively. There was significant difference between the pre-test and post-test values for the cardiovascular variables in the CHF and the AHI groups (p=0.000) except pulse pressure in female CHF patients where there was no significant difference (p=0.064). The CHF group had higher resting and post exercise respiratory rate than their AHI counterparts {male CHF patients = 24.1±0.7rpm and male AHI control=18.9± 0.4rpm; female CHF patients = 33.8 ±0.8rpm and female AHI control = 24.2± 0.5rpm (p=0.000)}.

The subjects in the CHF group covered significant lesser distance than their AHI control counterparts {male CHF patients = 432 ± 14.5m, male AHI control=510±10.1m (p=0.000); female CHF patients = 391±11.4m, female AHI control = 482± 18.4m (p=0.000)}.

CONCLUSION: The outcome of this study shows that functional exercise capacity is limited in individuals with CHF and that 6MWT may be used to assess functional limitations among individuals with chronic heart failure. The 6-minute walk test can also be recommended as a form of exercise to improve their cardiopulmonary function and activities of daily living.

IMPLICATIONS: The 6-minute walk test can be used clinically where sophisticated equipment for cardiopulmonary exercise test is not available to assess and monitor cardiopulmonary functional performance among individuals with chronic heart failure.

LIMITATIONS OF THE STUDY: Further studies with larger and heterogeneous population are recommended.

Key words: Chronic heart failure, blood pressure, 6-minute walk test.