Abstract 15265: Intra- and Inter-Individual Changes in Daily Resting Heart Rate Over Two Years for 92,457 Individuals

• Published in: Circulation (New York, N.Y.) N.Y.), 2019-11, Vol.140 (Suppl_1 Suppl 1), p.A15265-A15265
• Main Authors: Quer, Giorgio, Gouda, Pishoy, Galarnyk, Michael, Topol, Eric J, Steinhubl, Steven R
• Format: Article
• Language: English
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/circ.140.suppl_1.15265

IntroductionHeart rate is routinely measured but is rarely acted upon unless well out of a population-based normal range. In the era of wearable sensor technologies, heart rate can be continuously measured, providing new opportunities to understand longitudinal changes in the individual physiology.HypothesisIt is now possible to1) accurately identify a “normal” resting heart rate (RHR) for an individual, and 2) to measure potentially important variations in an individual’s heart rate over time, which can be associated to relevant outcomes.Methods92,457 individuals living in the US were included in a de-identified dataset who consistently (> 35 weeks over two years) wore a heart rate and activity wrist-worn tracker for at least 20 hours per day. RHR was measured using inter-beat intervals derived from the photoplethysmography sensor. Age and body mass index (BMI) were extrapolated from self-reported data.ResultsIndividual daily RHR was available for a median of 320 days (IQR242-438), providing a total of 32,741,021 daily RHR values. Mean individual daily RHR over the two years ranges from a minimum of 39.7 to a maximum of 108.6 BPM (Figure), with an average value over all individuals of 65.5+7.7 (females 66.7+7.5, males 63.4+7.6). Differences in the average individual RHR were associated with age, BMI, and average sleep. Seasonal variation was also noted, with the minimum average RHR among all individuals in late July and maximum the first week of January (Figure). For most individuals, RHR remained relatively stable short-term with a median change within a week of only 3 BPM. However, 20% of individuals experienced at least one week with a fluctuation in their RHR of 10 or more BPM.ConclusionsDay-to-day RHR varies widely between individuals but is relatively stable for each individual. Recognizing expected and unexpected long- and short-term changes in the trajectory of an individual’s daily RHR may prove to be an early warning of important physiologic changes.