Functional capacity in patients with congestive heart failure

Background: Six-minute walk distance (6MWd) is related to activities of dai ly living and is also an independent predictor of prognosis in patients wit h congestive heart failure (CHF). Therefore. it is important to determine f actors that contribute to the variability of this test. Methods and Results: We assessed the relationship between 6MWd and peak aer obic capacity (Vo(2)) and dynamic muscle strength in 180 patients with CHF (age, 66 +/- 10 years; 146 men, 34 women; ejection fraction, .29 +/- 0.08). We also hypothesized that a measure of work performed during the walk test (6MWw) would be a better indicator of exercise capacity than 6MWd. The 6MW d had weak to moderate correlations with dynamic muscle strength (r = 0.33 to 0.41) and peak Vo(2) (r = 0.48). However, 6MWw was strongly related to d ynamic muscle strength (r = 0.63 to 0.70) and peak Vo(2) (r = 0.77). Multiv ariate analysis indicated that a model combining dynamic muscle strength an d peak Vo(2) explained 69% of the variance in 6MWw, more than with peak Vo( 2) alone (R-2 = 0.59). Conclusions: Compared with 6MWd, 6MMw correlates significantly better with peak iio, and dynamic muscle strength, suggesting that 6MMw may be a better reflection of a patient's exercise capacity. Further-more, these results s uggest that an exercise program combining both aerobic and strength trainin g in patients with CHF may improve 6MWw and therefore 6MWd.