Association between physical activity measurements and key parameters of cardiopulmonary exercise testing in patients with heart failure

Background A hallmark characteristic of heart failure (HF) is reduced physical activity (PA) patterns. The relationship between key cardiopulmonary exercise testing (CPX) variables and PA patterns has not been investigated. Therefore, we evaluated PA patterns in patients with ischemic HF and its relationship to peak oxygen consumption (VO₂), the minute ventilation/carbon dioxide production (VE/VCO₂) slope, and the oxygen uptake efficiency slope (OUES). Methods and Results Sixteen patients with HF wore an accelerometer for six days to measure total steps/day as well as percentage of time at light, moderate, and vigorous PA. Symptom-limited CPX was performed on a treadmill using a ramping protocol. Total steps correlated with VO₂ (r = 0.64 P <.05), the VE/VCO₂ slope (r = -0.72; P <.05), and the OUES (0.63; P <.05). The percentage of time at light-intensity PA correlated with the VE/VCO₂ slope (r = 0.58; P <.05) and the OUES (r = -0.51; P <.05). The percentage of time at vigorous-intensity PA correlated with peak VO₂ (r = 0.55; P <.05) and the VE/VCO₂ slope (r = -0.52; P <.05). Conclusions PA assessed by accelerometer is significantly associated with key CPX variables in patients with HF.