Day-to-day measurement of physical activity and risk of atrial fibrillation

Abstract

Aims: The aim of this study was to investigate the association between within-individual changes in physical activity and onset of atrial fibrillation (AF).

Methods and results: A total of 1410 participants from the general population (46.2% women, mean age 74.7 ± 4.1 years) with risk factors but with no prior AF diagnosis underwent continuous monitoring for AF episodes along with daily accelerometric assessment of physical activity using an implantable loop recorder during ≈3.5 years. The combined duration of monitoring was ≈1.6 million days, where 10 851 AF episodes lasting ≥60 min were detected in 361 participants (25.6%) with a median of 5 episodes (2, 25) each. The median daily physical activity was 112 (66, 168) min/day. A dynamic parameter describing within-individual changes in daily physical activity, i.e. average daily activity in the last week compared to the previous 100 days, was computed and used to model the onset of AF. A 1-h decrease in average daily physical activity was associated with AF onset the next day [odds ratio 1.24 (1.18-1.31)]. This effect was modified by overall level of activity (P < 0.001 for interaction), and the signal was strongest in the tertile of participants with lowest activity overall [low: 1.62 (1.41-1.86), mid: 1.27 (1.16-1.39), and high: 1.10 (1.01-1.19)].

Conclusions: Within-individual changes in physical activity are associated with the onset of AF episodes as detected by continuous monitoring in a high-risk population. For each person, a 1-h decrease in daily physical activity during the last week increased the odds of AF onset the next day by ≈25%, while the strongest association was seen in the group with the lowest activity overall.

Clinical trial registration: ClinicalTrials.gov, identifier: NCT02036450.

Keywords: Accelerometry; Activity patterns; Atrial fibrillation; Continuous monitoring; Physical activity.

Graphical abstract

Figure 1

Graphical example of changes in recent compared to usual physical activity (ΔPA) and a pattern of ΔPA leading up to an AF episode. (A) Daily physical activity used to calculate ΔPA leading up to the day of AF onset (blue triangle): recent physical activity (during the most recent week, with a horizontal line illustrating the mean, PA_mean7d, green), and usual physical activity (during the prior 100 days, with a horizontal line illustrating the mean, PA_mean100d, red). (B) The pattern of ΔPA values leading up to an AF episode. Each day, ΔPA is calculated by subtracting PA_mean7d from PA_mean100d, where PA_mean7d is defined as the average daily physical activity in the week leading up to but not including that particular day, and PA_mean100d is defined as the average daily physical activity in the 100 days prior to that week. AF, atrial fibrillation.

Figure 2

Subplots illustrating physical activity and day-to-day change in physical activity in the study population. (A) Distribution of physical activity for all data points; one for each day for each participant. (B) Distribution of day-to-day change in physical activity, defined as average physical activity during the prior 100 days (PA_mean100d) subtracted by average physical activity in the recent week (PA_mean7d). To avoid overlap, a lag of 7 days was included between the two. PA, physical activity.

Figure 3

Subplots illustrating atrial fibrillation episodes in the study population. (A) Fraction of participants with AF onset on each day during the study period, with participants stratified into physical activity groups. (B) Overall percentage of days with AF onset for each participant, stratified by activity group. A Kruskal–Wallis test showed a significant difference between groups (P < 0.01) and a Tukey–Kramer analysis showed that all groups were significantly different from each other (P < 0.01). AF, atrial fibrillation; PA, physical activity.

Figure 4

Association between changes in recent compared to usual physical activity (ΔPA) and onset of atrial fibrillation grouped by overall physical activity after multivariate adjustment (M3). M3, model 3 adjusted for age, sex, hypertension, diabetes, heart failure, previous stroke, systemic arterial embolism or transient ischaemic attack, and previous myocardial infarction, percutaneous coronary intervention, or coronary artery bypass graft, the total number of prior atrial fibrillation episodes_, and annual season.