OTAKA YOHEI

We aimed to evaluate the applicability of a newly developed joint angle measurement system comprising six-axis inertial measurement unit sensors and tablet-based application for estimating joint angles from angular velocity and acceleration data. The application calculated orientation angles from single sensor data, with relative angles calculated using multiple sensors. In experiment 1, validity and reliability were examined using a test device. In experiment 2, static angles of five joints were calculated in four healthy participants using attached sensors and compared with universal goniometer values. In experiment 3, usability and satisfaction were evaluated using the System Usability Scale (SUS) and Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST)-like scale. In experiment 1, mean difference and root mean squared error (RMSE) between the developed system and test device were < 0.2° and < 1.0°, respectively, across all axes. In experiment 2, when data from all joints were pooled, mean difference and RMSE were 0.2° and 3.8°, respectively. Mean difference and RMSE across each joint were < 5°, indicating the system is comparable to universal goniometer. In experiment 3, median SUS and QUEST-like scores were 73.8 and 4.0, respectively, indicating good usability and satisfaction. The developed system has high accuracy and sufficient validity for human joint angles, with good usability and satisfaction.

OBJECTIVES: A new classification of heart failure based on the effects of medication has recently come into use. According to this classification, heart failure is divided into heart failure with normal ejection fraction (HFnEF; defined as an EF ≥55% for men and ≥60% for women) and non-HFnEF. However, the characteristics of patients with HFnEF are still unclear. Accordingly, in this study, we sought to identify the background characteristics, including non-cardiac factors, of patients with HFnEF. METHODS: We retrospectively divided 304 eligible patients who were hospitalized for worsening heart failure at our institution between December 2020 and December 2022 into an HFnEF group (n=37) and a non-HFnEF group (n=267) and compared their demographic and clinical characteristics. RESULTS: There were more elderly patients in the non-HFnEF group, along with fewer patients with coronary artery disease and low serum hemoglobin and NT-proBNP levels and a higher proportion of patients with a low skeletal muscle index (<7.0 kg/m2 for men and <5.7 kg/m2 for women). Multivariate analysis with addition of patient sex identified a low skeletal muscle index (odds ratio 2.96, p<0.01) to be an independent determinant of HFnEF along with older age and low NT-proBNP. CONCLUSIONS: A low skeletal muscle index was significantly more common in patients with HFnEF than in those with non-HFnEF. Intensive nutrition and exercise therapy to increase skeletal muscle mass may improve the prognosis in patients with HFnEF who respond poorly to standard pharmacological treatment.