L-Shaped association of fasting serum total bile acids with atrial fibrillation risk in the elderly

Serum total bile acid (BA) concentration, while linked to cardiovascular disease, lacks established associations with atrial fibrillation (AF). This cross-sectional study investigated the relationship between fasting serum total BA and AF prevalence/classification (paroxysmal vs persistent) in 522 patients aged ≥75 years. Participants were categorized by AF diagnosis and stratified by BA tertiles. Results revealed significantly lower serum total BA concentrations in AF patients compared to sinus rhythm controls. Notably, within the AF group, persistent cases exhibited lower BA levels than paroxysmal cases (3.00 (1.67-5.00) vs 3.80 (2.30-6.40) μmol/L, <i>p</i> = 0.005). Analysis demonstrated a nonlinear L-shaped relationship between BA and AF prevalence (inflection point: 4.08 μmol/L), with lower BA levels independently associated with higher AF risk (adjusted odds ratio = 1.84, 95% CI: (1.03-3.29), <i>p</i> = 0.040). These findings establish an L-shaped correlation, indicating reduced fasting serum total BA as an independent predictor for increased AF risk in the elderly.