I had the honor of discussing the WATCHFUL trial in an #AHA23 Featured Science session titled “Exercise Is Life (and Death) – Approaches in Athletes, Arrhythmias, and Heart Failure.” As presented by Jan Bělohlávek, M.D., Ph.D., the WATCHFUL trial evaluated the effect of a walking lifestyle intervention, which involved behavioral coaching and check-ins to assess physical activity, on functional capacity in patients with heart failure and reduced ejection fraction. The primary endpoint of the trial was the change in 6-minute walk distance after six months.
Participants were more than 80% compliant with the walking intervention. The intervention led to a 25% increase in daily step count, an 8.2-minute increase in moderate to vigorous physical activity, and an improvement in self-reported overall well-being. However, the primary endpoint was not met because the walking lifestyle intervention did not increase the 6-minute walk test (6MWT) distance at six months.
As the discussant for this presentation, I attributed the lack of improvement in the 6MWT to the lower intensity of the exercise intervention as compared with traditional cardiac rehabilitation exercise prescriptions. Prior data demonstrated that exercise volume (the product of exercise intensity and duration) is strongly correlated with functional improvement. I postulated that, given the lower intensity of the exercise intervention, a longer duration of follow-up might have been needed to see clinical improvements in functional status.