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Abstract
We previously demonstrated that heart rate (HR) variability obtained by daytime ambulatory monitoring and that of daily home measurement associated differently with cardiovascular mortality risk; cardiovascular mortality was linked with decreased daytime ambulatory HR variability and increased day-by-day home HR variability. The aim of this study was to identify factors contributing to each variability, clarifying possible reasons for their different predictive values. We obtained daytime ambulatory HR and home HR in 538 individuals of a general Japanese population aged ≥55 years. Daytime ambulatory HR variability and day-by-day home HR variability were estimated as a standard deviation measured every 30 min by daytime ambulatory monitoring and day-by-day home measurements once in the morning for 4 weeks, respectively. There was only weak correlation between daytime ambulatory HR variability and day-by-day home HR variability (r = 0.08∼0.14). In a multiple regression model, daytime ambulatory HR variability was associated with daytime ambulatory HR (P < 0.0001), daytime ambulatory blood pressure (BP) variability (P < 0.0001), and male sex (P = 0.003), while negatively associated with daytime ambulatory systolic blood pressure (SBP) (P < 0.0001) and smoking (P = 0.038). Meanwhile, day-by-day home HR variability was positively associated with home HR (P < 0.0001), day-by-day home BP variability (P < 0.0001), and male sex (P = 0.018). Associated factors of daytime ambulatory HR variability and day-by-day home HR variability were different. Our findings suggest that HR variabilities by different intervals of measurements might be mediated by different mechanisms.
ACKNOWLEDGMENTS
This study was supported by the Ministries of Education, Culture, Sports, Science and Technology (grants for scientific research: 18390192, 18590587, 19590929, 19790423, 20590629, 21390201, 21591016, 22590767, and 22790556) and of Health, Labor and Welfare (health science research grants and medical technology evaluation grants), Grant-in-Aid for Japan Society for the Promotion of Science (JSPS) fellows (18.54042, 19.7152, 20.7198, 20.7477, and 20.54043), the Japan Atherosclerosis Prevention Fund, and National Cardiovascular Research Grants and Biomedical Innovation Grants.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper