Background: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in adults, yet its underlying pathophysiology remains poorly understood. This study assessed whether circulating biomarker concentrations differ in paroxysmal AF patients during an acute episode compared to sinus rhythm.

Methods: The Time of Calamity study is a prospective biomarker study within the RACE V study. Patients underwent venous blood sampling in sinus rhythm at inclusion in RACE V, as well as during a subsequent acute episode of AF for which patients reported to the hospital. Ten biomarkers were analyzed.

Results: Thirty-nine patients (mean age 60 ± 9 years, 10 (25 %) women) were enrolled. During an acute AF episode, dickkopf-related protein 3 and insulin-like growth factor binding protein 7 were significantly lower, while N-terminal pro B-type natriuretic peptide (NT-proBNP), high-sensitive troponin T (hsTnT), growth differentiation factor 15, and interleukin 6 were significantly higher (all p < 0.05).

Conclusions: Biomarker concentrations in paroxysmal AF patients are dynamic and differ between sinus rhythm and acute AF episodes. Notably, NT-proBNP and hsTnT, commonly used in clinical practice, were significantly elevated during an acute AF episode.

Keywords: Atrial fibrillation; Biomarkers; Continuous rhythm monitoring.