BackgroundThe relationship between remnant cholesterol (RC) and atrial fibrillation (AF) remains unclear. ObjectiveTo comprehensively explore the association between RC characteristics and new-onset AF. MethodsData from five follow-up visits of the ARIC study were analyzed. RC were multidimensionally evaluated in four characteristics, including baseline level, variability, cumulative exposure and trajectory. Baseline RC was obtained from the initial visit (V1), and new-onset AF was monitored in V2 to V5 (cohort 1, n=14450). RC variability, cumulative RC and RC trajectory were calculated by RC values gathered from V1 to V3, and new-onset AF was monitored in V4 and V5 (cohort 2, n=11012). Participants were divided into four groups based on quartiles or trajectories. Cox proportional hazards analyses were used to investigate the relationship between RC characteristics and AF. ResultsFollowing a median follow-up of 22.39 years in cohort 1 and 16.71 years in cohort 2, a total of 1993 AF events in cohort 1 and 1571 in cohort 2 were identified. Participants with the highest quartile exhibited an elevated risk of new-onset AF, with the multivariable-adjusted HRs of 1.35 (P=0.009) for baseline RC and 1.26 (P=0.09) for RC variability. Although the highest quartile of cumulative RC (P=0.130) and the high-increasing trajectory (P=0.322) did not demonstrate a statistically significant association with AF occurrence, they indicate a trend towards a heightened risk. ConclusionOur findings reveal that higher levels of RC, particularly at baseline and in variability, are associated with an increased risk of AF.