Abstract Body (Do not enter title and authors here): Introduction/Background
The development of atrial fibrillation (AF) is increasingly understood as a multifactorial process involving genetics, lifestyle habits, and catecholamine tone. Data is lacking on the role of stress response in AF-mediated stroke. Allostatic load (AL), a quantitative biochemical assessment of host stress response, remains understudied in the context of AF and associated stroke events.

Questions/Hypothesis
We hypothesized that higher quartiles of AL would be associated with prevalent AF and increased risk of stroke during the follow-up period independent of baseline AF status or social determinants of health (SDOH).

Methods/Approach
Patients enrolled in the national, prospective REGARDS (Reasons for Geographic and Racial Differences in Stroke) cohort were stratified into quartiles of AL. Prevalent AF at baseline was defined by self-report, AF on baseline visit ECG, or the use of antiarrhythmic medication. Stroke was adjudicated independently by a clinical committee. Univariate results were adjusted for SDOH found to be significant across AL quartiles ([education < high school, annual income <$35000, rural residence, high poverty zip-code], model 1). Kaplan-Meier (KM) time-to-event curves were constructed for time to stroke according to AL quartile.

Results/Data
In total, 13194 patients were included in the analysis, among whom 741 (5.6%) had stroke during a mean follow-up period of 11.5 years. Prevalence of baseline AF (Table 1) differed by AL quartile (Q1=188, Q2=239, Q3=302, Q4=313, p=<0.001 pre and post-adjustment). Rates of stroke (Table 2) differed by AL quartile (Q1=98, Q2=162, Q3=232, Q4=249, p=<0.001 pre and post-adjustment). KM Curves (Figure 1), show that time to stroke differed by AL quartile across the follow-up period.

Conclusions
In this prospective analysis for patients in the REGARDS cohort, higher AL quartile was associated with higher risk of baseline AF and rate of stroke before and after adjustment for SDOH. Unadjusted time to stroke also differed by AL quartile.