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

Objective: 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). Design: Prospective, randomized, single-blinded (by researchers to patient group) comparison of 2 groups of HFpEF patients. Setting: Hospital and clinic records; ambulatory outpatients. Participants: Participants (N=47) randomly assigned to an attention control (AC) (n=24) or exercise training (ET) (n=23) group. Intervention: The ET group performed cycling and walking at 50% to 70% of peak oxygen uptake ((V) over doto(2)peak) intensity (3d/wk, 60min each session). Main Outcome Measures: (V) over doto(2)peak, ventilatory threshold (VT), and 6-MWT distance were measured at baseline and after the 16-week study period. Results: 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) over doto(2)peak 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) over doto(2)peak 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). Conclusions: 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) over doto(2)peak in this patient population. (C) 2016 by the American Congress of Rehabilitation Medicine