FGF23 and atrial fibrillation: A recent study observed altered biomarker levels in patients with paroxysmal AF compared to those in SR and concluded that it may reflect dynamic pathophysiological changes during acute AF episodes.46 Although we only observed the reduced levels of IL-6 and FGF-23 in the group with spontaneous conversion to SR, reversed pathophysiological changes may have resulted in lower biomarker levels in this group.