Abstract 12573: Step Count, Self-Reported Physical Activity, and Five-Year Risk for Incident Atrial Fibrillation

Background: Obesity and sedentary lifestyles are known risk factors for atrial fibrillation (AF). Wearable devices such as smartwatches present an opportunity to investigate relations between daily step count and AF risk. Hypothesis: Higher daily step count, as measured by wearable devices, will be associated with a smaller five-year risk of AF, as predicted by CHARGE-AF score. Methods: Participants from the electronic Framingham Heart Study (eFHS) utilized an AppleWatch. Individuals with diagnosed AF were excluded. Daily step count, watch wear time (hours, days), and self-reported physical activity were collected. Individual five-year risk of AF was estimated using The Cohorts for Heart and Aging Research in Genomic Epidemiology AF (CHARGE-AF) score. Relation between daily step counts and five-year predicted AF risk was examined with linear regression adjusted for age, sex, and wear time. Secondary analyses examined effect modification by sex and obesity (body mass index ≥30 kg/m 2 ), as well as relation between self-reported physical activity and predicted 5-year AF risk. Results: We examined 932 eFHS participants (mean age 53±9 years, 61% female) with a median daily step of 7360 (25 th -75 th percentile 5841-9060). Most participants (89.2%) had <2.5% CHARGE-AF risk. Every 1000 steps were associated with 0.08% lower CHARGE-AF risk ( P <0.001). A stronger association was observed in men and individuals with obesity. In contrast, self-reported physical activity was not associated with CHARGE-AF risk. Conclusion: Higher daily step count was associated with lower predicted 5-year risk of AF, and this relation was stronger in men and participants with obesity. The utility of a wearable daily step counter for risk reduction for AF merits further investigation.