Abstract
A sedentary lifestyle is prevalent among patients with heart failure (HF) and is associated with poor prognosis and survival, possibly owing to the displacement of health-enhancing behaviors, such as physical activity (PA). However, there is limited evidence examining the displacement effects of reducing duration of sedentary time (ST) on clinical outcomes in patients with HF. The current study examined the theoretical effects of relocating ST with PA on all-cause and cardiovascular disease (CVD)-specific mortality risks in patients with HF. We analyzed 265 patients with HF who participated in the National Health and Nutrition Examination Survey from 2003 to 2006. Cox proportional hazards regression model was fitted to estimate mortality risks based on objectively measured ST well as time spent in light-intensity PA (LPA) and moderate- and vigorous-intensity PA (MVPA). The theoretical changes in the hazard ratio (HR) by replacing ST with LPA or MVPA were examined using isotemporal substitutional modeling. On average, patients with HF spent 70% of waking hours per day in ST (9.01 hours), followed by LPA (29%; 3.75 hours) and MVPA (1%; 0.13 hours). Ten-minute substitution of ST with LPA was associated with significantly lower all-cause and CVD-specific mortality risks (hazard ratio [HR]=0.93 for both). The mortality risks progressively decreased as more ST was relocated to LPA. The relocation effects of ST with MVPA were not statistically significant, possibly because of limited MVPA accrued in this clinical population. The current study provides empirical evidence about the potential health benefits of replacing a modest amount of ST with LPA among patients with HF.