Abstract Body: Introduction: Atrial fibrillation (AF) and late onset epilepsy (LOE) are common conditions, particularly among older adults. These conditions have several shared risk factors, and there is mechanistic evidence that epilepsy can lead to cardiac dysfunction and vice versa. We conducted a population-based study to investigate this potential bidirectional association between AF and LOE.

Methods: A total of 15,792 ARIC participants were followed from baseline (1987-1989) to 2022. At baseline, we excluded those with conduction disorders, those on anti-arrhythmic medications, those with prevalent AF and LOE events, and those with events within 2 years of baseline. AF and LOE were identified through active surveillance, primarily using ICD codes. AF and LOE were modeled as time-dependent exposures, and covariates were measured at baseline or updated throughout follow-up when modeled as incident mediators. We used Cox proportional hazards models to assess the association with each incident outcome, adjusting for demographics and cardiovascular disease (CVD) risk factors.

Results: After exclusions, our analysis included 15,138 participants (26% black race, 55% female, mean age 54). In demographic and CVD risk-factor adjusted models (Table, Model 3), AF was associated with a 2.09 times higher risk of LOE (95% CI: 1.72-2.53). After additional adjustment for incident CVD, the risk was attenuated but remained significant [HR (95% CI): 1.38 (1.12-1.70]. In Model 3, LOE was associated with a 1.71 times higher risk of AF (95% CI: 1.40-2.09). After adjustment for incident CVD, the risk was attenuated but remained significant [HR (95% CI): 1.24 (1.01-1.52)].

Conclusion: In this population-based cohort, there was a bidirectional association between AF and LOE, even after adjustment for incident CVD, supporting a shared mechanistic pathway hypothesis.