Predicting atrial fibrillation after an acute coronary syndrome: insights from the BACS & BAMI study

BACKGROUND: Atrial fibrillation (AF) is among the most prevalent arrhythmias. Its onset after an acute coronary syndrome (ACS) is especially notable given the high coronary disease burden. Mineral metabolism, particularly fibroblast growth factor 23 (FGF23), has been linked to cardiovascular outcomes. This study examines whether FGF23, related markers and other variables can predict AF occurrence after an ACS, considering age differences. METHODS: Data were obtained from the BACS & BAMI study, including 1189 patients from five Madrid hospitals. Baseline clinical characteristics and laboratory results were recorded. Patients were monitored annually through clinical appointments. Univariate and multivariate Cox analyses were conducted separately for patients aged ≤ 65 and > 65 years, based on CHA2DS2-VA thromboembolic score. RESULTS: Over a follow-up of 5.44 (3.03-7.46) years, 5.5% of patients developed AF. In those ≤ 65 years, FGF23 was an independent predictor of the development of AF (HR 1.37 [1.04, 1.79] per 100-unit rise; p = 0.026). Among patients > 65 years, a history of stroke was associated with a heightened risk (HR 2.75 [1.03, 7.34]; p = 0.044), while beta-blocker therapy appeared to be protective (HR 0.42 [0.23, 0.78]; p = 0.007). Previous AF consistently forecasted recurrence across both groups (HR 11.3 [2.92, 43.6]; p = 0.002 and HR 6.41 [3.13, 13.1]; p < 0.001, respectively). CONCLUSIONS: FGF23 seems to be an independent and positive predictor of AF after an ACS in patients ≤ 65 years, whereas in older individuals, beta-blocker therapy emerges as a potential protective measure. These insights may enhance current risk models with age-specific adjustments and encourage more tailored clinical strategies in post-ACS patients.