Association Between 6-Minute Walk Test Distance and Objective Variables of Functional Capacity After Exercise Training in Elderly Heart Failure Patients With Preserved Ejection Fraction: A Randomized Exercise Trial.

Abstract

To evaluate the change in the 6-minute walk test (6-MWT) distance relative to changes in key functional capacity measures after 16 weeks of exercise training in older patients (≥65y) who have heart failure with preserved ejection fraction (HFpEF). Prospective, randomized, single-blinded (by researchers to patient group) comparison of 2 groups of HFpEF patients. Hospital and clinic records; ambulatory outpatients. Participants (N=47) randomly assigned to an attention control (AC) (n=24) or exercise training (ET) (n=23) group. The ET group performed cycling and walking at 50% to 70% of peak oxygen uptake (V˙o₂peak) intensity (3d/wk, 60min each session). V˙o₂peak, ventilatory threshold (VT), and 6-MWT distance were measured at baseline and after the 16-week study period. At follow-up, the 6-MWT distance was higher than at the baseline in both the ET (11%, P=.005) and AC (9%, P=.004) groups. In contrast, V˙o₂peak and VT values increased in the ET group (19% and 11%, respectively; P=.001), but decreased in the AC group at follow-up (2% and 0%, respectively). The change in V˙o₂peak versus 6-MWT distance after training was also not significantly correlated in the AC group (r=.01, P=.95) or in the ET group (r=.13, P=.57). The change in 6-MWT distance and VT (an objective submaximal exercise measure) was also not significantly correlated in the AC group (r=.08, P=.74) or in the ET group (r=.16, P=.50). The results of this study challenge the validity of using the 6-MWT as a serial measure of exercise tolerance in elderly HFpEF patients and suggest that submaximal and peak exercise should be determined objectively by VT and V˙o₂peak in this patient population.