Six-minute walk test and heart rate variability: lack of association in advanced stages of heart failure

Abstract

BACKGROUND: The 6-minute walk and heart rate variability have been used to assess mortality risk in patients with heart failure, but their relationship to each other and their usefulness for predicting mortality at 1 year are unknown. OBJECTIVE: To assess the relationships between the 6-minute walk test, heart rate variability, and 1-year mortality. METHOD: A sample of 113 patients in advanced stages of heart failure (New York Heart Association Functional Class III-IV, left ventricular ejection < 0.25) were studied. All 6-minute walks took place in an enclosed, level, measured corridor and were supervised by the same nurse. Heart rate variability was measured by using (1) a standard-deviation method and (2) Poincare plots. Data on RR intervals obtained by using 24-hour Holter monitoring were analyzed. Survival was determined at 1 year after the Holter recording. RESULTS: The results showed no significant associations between the results of the 6-minute walk and the two measures of heart rate variability. The results of the walk were related to 1-year mortality but not to the risk of sudden death. Both measures of heart rate variability had significant associations with 1-year mortality and with sudden death. However, only heart rate variability measured by using Poincare plots was a predictor of total mortality and risk of sudden death, independent of left ventricular ejection fraction, serum levels of sodium, results of the 6-minute walk test, and the standard-deviation measure of heart rate variability. CONCLUSIONS: Results of the 6-minute walk have poor association with mortality and the two measures of heart rate variability in patients with advanced-stage heart failure and a low ejection fraction. Further studies are needed to determine the optimal clinical usefulness of the 6-minute walk and heart rate variability in patients with advanced-stage heart failure.

Clinical Correlates and Prognostic Significance of Six-minute Walk Test in Patients with Primary Pulmonary Hypertension

“…The six-minute walk test is a submaximal exercise test that can be performed by a patient not tolerating maximal exercise tests (6). The test is very simple, requires inexpensive equipment, and is reproducible.…”

“…The six-minute walk test was performed in all patients with PPH and 16 age-and sex-matched healthy volunteers according to a standardized protocol (6,17). They walked along an enclosed, level, measured corridor.…”

Reference values of 6 minutes walk test (6 MWT) in Bangladeshi healthy subjects aged 25-55 years

“…It has shown to reflect the capacity to undertake day-to-day activities and correlates well with health related quality of life scores. 3 Additionally, among patients with moderate to severe COPD, 4 and congestive heart failure, 5 the total distances covered during the 6MWT has shown a moderately strong correlation with the peak oxygen uptake measured during an incremental cycle ergometry test. A reduction in walking distance is frequently multifactorial and may result from a varied set of disorders that afflict a series of physiological variables engaged during exercise.…”

Clinical determinants of poor six‐minute walk test performance in patients with left ventricular systolic dysfunction and no major structural heart disease

“…The six‐minute walk test (6‐MWT) is used to estimate functional capacity in patients with a variety of medical conditions, and can be performed by those who are unable or unwilling to undertake formal treadmill or bicycle exercise tests [1]. The test is simple to perform, requires inexpensive equipment, is safe because patients are self‐paced during exertion, and is fairly reproducible provided it is well standardized [2].…”