Fitbit-measured physical activity is inversely associated with incident atrial fibrillation among All of Us participants.

Background: Individuals who report meeting weekly moderate to vigorous physical activity (MVPA) guidelines have lower risk of atrial fibrillation (AF). However existing studies have relied on subjective questionnaires or short-duration (<1 week) objective assessments using accelerometry. The objective of this research was to investigate an association between MVPA levels and the incidence of AF, utilizing long-term, free-living accelerometry data.

Methods: 1-year Fitbit data, in addition to survey and electronic health record (EHR) data, were extracted from the NIH All of Us (AoU) research database. Cox proportional hazards regression was used to model the association of average MVPA and incident AF over a five-year follow-up period.

Results: 15570 AoU participants were included (52±16 years, 71% female, 79% White, BMI 28.9±5.0 kg/m², 41±12 complete weeks of Fitbit wear). 97 individuals (0.6%) experienced incident AF in the five-year follow-up period. Every additional hour of MVPA was associated with 8% lower AF risk (HR = 0.92 [0.86,0.99], p=0.02). In a subset of 10533 participants with genomic data, this association persisted after adjustment for AF genetic risk score.

Conclusions: Higher amounts of objectively measured MVPA, measured using free-living, long-term accelerometry data, were inversely associated with risk of incident AF, independent of clinical and genetic risk factors.