Prognostic value of the 6 min walk test and self-perceived symptom severity in older patients with chronic heart failure

Background: The 6 min walk test (6-MWT) is a simple and popular test for evaluating functional status in patients with chronic heart failure (CHF). However, the prognostic value of the 6-MWT in a large, representative sample of CHF patients, and in patients with different degrees of left ventricular systolic dysfunction (LVSD) remains unclear. Methods and results: Of an initial population of 1592 patients, 212 died representing a crude death rate of 13.3%. In surviving patients, the median time to follow-up period was 36.6 months [inter-quartile range (IQR) 28-45 months]. Five variables remained independent predictors of all-cause mortality; decreasing 6-MWT distance, self-perceived signs of breathlessness at night (SOBAN), beta-blocker usage, elevated log NT-proBNP, and reduced haemoglobin concentration. We also dichotomized our analysis by LVSD status (≤mild LVSD or >mild LVSD). For patients with >mild LVSD, 6-MWT remained an important prognostic indicator but not in patients with ≤mild LVSD. Conclusion: The 6-MWT is an important independent predictor of mortality in CHF patients, and this was especially evident in patients with >mild LVSD. The 6-MWT provides little prognostic utility in patients with ≤mild LVSD. While log NT-proBNP was the most potent independent predictor, an additive prognostic effect was evident with the additional selection of 6-MWT. Patients' self-perceived symptoms, especially SOBAN was an independent predictor of mortality in our patients.