Relationship Between the Change in Post-Cardiovascular Surgery Patients’ 6-min Walking Distance and Physical Activity During Hospitalization

Background: The 6-min walking distance (6MWD) is an indicator of exercise tolerance in post-cardiovascular surgery patients and is associated with life expectancy. The association between the physical activity levels of these patients during hospitalization and changes in their 6MWD and the association by activity types are unknown. We investigated the association between 6MWD changes and physical activity by activity types in post-cardiovascular surgery patients. Methods and Results: Patients who had undergone cardiovascular surgery (n=70) were divided into 6MWD≥0 and 6MWD<0 groups based on the difference between their pre-surgery and pre-discharge 6MWD values. The physical activity of each patient after transfer from the intensive care unit (ICU) to the general ward was objectively measured with a triaxial accelerometer. Activity types were classified as locomotive and non-locomotive, with intensity divided into light-intensity physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). The 6MWD≥0 group was significantly younger and had earlier days of ADL independence than 6MWD<0 group. In the first post-ICU discharge week, the 6MWD≥0 group engaged in significantly higher locomotive MVPA, and significantly higher non-locomotive LPA and MVPA in the following week, compared with the 6MWD<0 group. Conclusions: Among post-cardiovascular surgery patients, physical activity was higher in those with an increase in 6MWD at discharge compared with pre-surgery levels. Notably, locomotive activity was higher in the first week after ICU discharge, while non-locomotive activity increased from the second week.